ORCID Profile
0000-0002-2472-7955
Current Organisation
Curtin University
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Motor Control | Sensory Processes, Perception and Performance | Psychology | Biological Psychology (Neuropsychology, Psychopharmacology, Physiological Psychology)
Publisher: Cold Spring Harbor Laboratory
Date: 26-10-2020
DOI: 10.1101/2020.10.25.354340
Abstract: Sensorimotor adaptation is an important part of our ability to perform novel motor tasks (i.e., learning of motor skills). Efforts to improve adaptation in healthy and clinical patients using non-invasive brain stimulation methods have been hindered by interin idual and intra-in idual variability in brain susceptibility to stimulation. Here, we explore unpredictable loud acoustic stimulation as an alternative method of modulating brain excitability to improve sensorimotor adaptation. In two experiments, participants moved a cursor towards targets, and adapted to a 30° rotation of cursor feedback, either with or without unpredictable acoustic stimulation. Acoustic stimulation improved initial adaptation to sensory prediction errors in Study 1, and improved overnight retention of adaptation in Study 2. Unpredictable loud acoustic stimulation might thus be a potent method of modulating sensorimotor adaptation in healthy adults.
Publisher: American Psychological Association (APA)
Date: 2014
DOI: 10.1037/BNE0000007
Abstract: A loud auditory stimulus (LAS) presented during movement preparation can result in an earlier than normal movement onset. This effect had initially been assumed to be independent of the sensorial modality people attended to trigger their responses. In 2 experiments, we tested whether this assumption was warranted. In Experiment 1, we employed a timed response paradigm in which participants were cued in relation to the precise moment of movement onset of their motor responses. In the visual task, participants were cued about movement onset via visual cues on a monitor screen. In the auditory task, participants were cued about movement onset through tones delivered via headphones. During both tasks, we delivered an unexpected LAS 200 ms prior to movement onset. We found that the responses were initiated earlier by the LAS in the auditory task in relation to the visual task. In Experiment 2, we presented participants with a sequence of tones and flashes interleaved. The participants' task was to ignore either the tones or the flashes and make a movement in sync with the last tone or flash. The results showed that when participants had to ignore the task-irrelevant tones in the background, the early responses were much reduced. In contrast, when participants had to pay attention to the tones and ignore the flashes, the early release of anticipatory actions was robust. Our results indicate that attention to a specific sensorial modality can affect the early release of motor responses by LAS.
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.HUMOV.2012.11.008
Abstract: The elaboration of learning strategies has been considered a key factor to explain sensorimotor learning gains obtained in self-scheduled practice conditions. Nevertheless, the effect of prior knowledge of the testing context (i.e., the learning goal) on that process has been neglected. This study sought to determine whether: (a) learners in a self-controlled condition make different choices contingent on having or not having a learning goal (b) providing a learning goal would modify the effects of a self-controlled practice condition, and (c) the effect of providing a learning goal would be due to the augmented cognitive effort or to the practice schedule resulting from the learning strategies. The results show that prior knowledge of a variable testing context affects the elaboration of learning strategies and improves skill acquisition in a self-scheduled practice condition. Furthermore, learning gains can be attributed to the self-imposed practice schedule resulting from the learning strategies, and not to the process of elaborating them.
Publisher: Wiley
Date: 30-09-2020
DOI: 10.1111/EJN.14973
Abstract: There has been much debate concerning whether startling sensory stimuli can activate a fast‐neural pathway for movement triggering (StartReact) which is different from that of voluntary movements. Activity in sternocleidomastoid (SCM) electromyogram is suggested to indicate activation of this pathway. We evaluated whether SCM activity can accurately identify trials which may differ in their neurophysiological triggering and assessed the use of cumulative distribution functions (CDFs) of reaction time (RT) data to identify trials with the shortest RTs for analysis. Using recent data sets from the StartReact literature, we examined the relationship between RT and SCM activity. We categorised data into short/longer RT bins using CDFs and used linear mixed‐effects models to compare potential conclusions that can be drawn when categorising data on the basis of RT versus on the basis of SCM activity. The capacity of SCM to predict RT is task‐specific, making it an unreliable indicator of distinct neurophysiological mechanisms. Classification of trials using CDFs is capable of capturing potential task‐ or muscle‐related differences in triggering whilst avoiding the pitfalls of the traditional SCM activity‐based classification method. We conclude that SCM activity is not always evident on trials that show the early triggering of movements seen in the StartReact phenomenon. We further propose that a more comprehensive analysis of data may be achieved through the inclusion of CDF analyses. These findings have implications for future research investigating movement triggering as well as for potential therapeutic applications of StartReact.
Publisher: Wiley
Date: 09-11-2018
DOI: 10.1111/EJN.14213
Abstract: Perturbations of sensory feedback evoke sensory prediction errors (discrepancies between predicted and actual sensory outcomes of movements), and reward prediction errors (discrepancies between predicted rewards and actual rewards). When our task is to hit a target, we expect to succeed in hitting the target, and so we experience a reward prediction error if the perturbation causes us to miss it. These discrepancies between intended task outcomes and actual task outcomes, termed "task errors," are thought to drive the use of strategic processes to restore success, although their role is incompletely understood. Here, as participants adapted to a 30° rotation of cursor feedback representing hand position, we investigated the role of task errors in sensorimotor adaptation: during target-reaching, we either removed task errors by moving the target mid-movement to align with cursor feedback of hand position, or enforced task error by moving the target away from the cursor feedback of hand position, by 20-30° randomly (clockwise in half the trials, counterclockwise in half the trials). Removing task errors not only reduced the extent of adaptation during exposure to the perturbation, but also reduced the amount of post-adaptation aftereffects that persisted despite explicit knowledge of the perturbation removal. Hence, task errors contribute to implicit adaptation resulting from sensory prediction errors. This suggests that the system which predicts the sensory consequences of actions via exposure to sensory prediction errors is also sensitive to reward prediction errors.
Publisher: American Physiological Society
Date: 05-2015
Publisher: eLife Sciences Publications, Ltd
Date: 07-09-2017
Publisher: Cold Spring Harbor Laboratory
Date: 27-04-2021
DOI: 10.1101/2021.04.26.441558
Abstract: When intense sound is presented during light muscle contraction, inhibition of the corticospinal tract is observed. During action preparation, this effect is reversed, with sound resulting in excitation of the corticospinal tract. We investigated how the combined maintenance of a muscle contraction during preparation for a ballistic action impacts the magnitude of the facilitation of motor output by a loud acoustic stimulus (LAS) – a phenomenon known as the StartReact effect. Participants executed ballistic wrist flexion movements and a LAS was presented simultaneously with the imperative signal in a subset of trials. We examined whether the force level or muscle used to maintain a contraction during preparation for the ballistic response impacted reaction time and/or the force of movements triggered by the LAS. These contractions were sustained either ipsilaterally or contralaterally to the ballistic response. The magnitude of facilitation by the LAS was greatest when low force flexion contractions were maintained in the limb contralateral to the ballistic response during preparation. There was little change in facilitation when contractions recruited the contralateral extensor muscle, or when they were sustained in the same limb that executed the ballistic response. We conclude that a larger network of neurons which may be engaged by a contralateral sustained contraction prior to initiation may be recruited by the LAS, further contributing to the motor output of the response. These findings may be particularly applicable in stroke rehabilitation where engagement of the contralesional side may increase the benefits of a LAS to the functional recovery of movement.
Publisher: Wiley
Date: 22-11-2017
DOI: 10.1111/APHA.12822
Publisher: Wiley
Date: 12-12-2016
DOI: 10.1111/APHA.12627
Abstract: Loud acoustic stimuli can unintentionally elicit volitional acts when a person is in a state of readiness to execute them (the StartReact effect). It has been assumed that the same subcortical pathways and brain regions underlie all instances of the StartReact effect. They are proposed to involve the startle reflex pathways, and the eliciting mechanism is distinct from other ways in which sound can affect the motor system. We present an integrative review which shows that there is no evidence to support these assumptions. We argue that motor command generation for learned, volitional orofacial, laryngeal and distal limb movements is cortical and the StartReact effect for such movements involves transcortical pathways. In contrast, command generation for saccades, locomotor corrections and postural adjustments is subcortical and subcortical pathways are implicated in the StartReact effect for these cases. We conclude that the StartReact effect is not a special phenomenon mediated by startle reflex pathways, but rather is a particular manifestation of the excitatory effects of intense stimulation on the central nervous system.
Publisher: Wiley
Date: 09-10-2020
DOI: 10.1111/PSYP.13493
Abstract: Loud acoustic stimuli presented during movement preparation can shorten reaction time and increase response forcefulness. We examined how efferent connectivity of an agonist muscle to reticulospinal and corticospinal pathways, and the level of prepared movement force, affect reaction time and movement execution when the motor response is triggered by an intense acoustic stimulus. In Experiment 1, participants executed ballistic wrist flexion and extension movements of low and high force in response to visual stimuli. A loud acoustic stimulus (LAS 105 dBa) was presented simultaneously with the visual imperative stimulus in probe trials. In Experiment 2, participants executed ballistic wrist flexion movements ranging from 10%-50% of maximum voluntary contraction with a LAS presented in probe trials. The shortening of response initiation was not affected by movement type (flexion or extension) or prepared movement force. Enhancement of response magnitude, however, was proportionally greater for low force movements and for the flexor muscle. Changes in peak force induced by the intense acoustic stimulus indicated that the neural activity introduced to motor program circuits by acoustic stimulation is additive to the voluntary neural activity that occurs due to movement preparation, rather than multiplicative.
Publisher: eLife Sciences Publications, Ltd
Date: 23-10-2017
DOI: 10.7554/ELIFE.26713
Abstract: The characteristics of goal-directed actions tend to resemble those of previously executed actions, but it is unclear whether such effects depend strictly on action history, or also reflect context-dependent processes related to predictive motor planning. Here we manipulated the time available to initiate movements after a target was specified, and studied the effects of predictable movement sequences, to systematically dissociate effects of the most recently executed movement from the movement required next. We found that directional biases due to recent movement history strongly depend upon movement preparation time, suggesting an important contribution from predictive planning. However predictive biases co-exist with an independent source of bias that depends only on recent movement history. The results indicate that past experience influences movement execution through a combination of temporally-stable processes that are strictly use-dependent, and dynamically-evolving and context-dependent processes that reflect prediction of future actions.
Publisher: The Royal Society
Date: 07-09-2012
Abstract: Reliable estimates of time are essential for initiating interceptive actions at the right moment. However, our sense of time is surprisingly fallible. For instance, time perception can be distorted by prolonged exposure (adaptation) to movement. Here, we make use of this to determine if time perception and anticipatory actions rely on the same or on different temporal metrics. Consistent with previous reports, we find that the apparent duration of movement is mitigated by adaptation to more rapid motion, but is unchanged by adaptation to slower movement. By contrast, we find symmetrical effects of motion-adaptation on the timing of anticipatory interceptive actions, which are paralleled by changes in perceived speed for the adapted direction of motion. Our data thus reveal that anticipatory actions and perceived duration rely on different temporal metrics.
Publisher: Springer Science and Business Media LLC
Date: 23-06-2011
DOI: 10.1007/S00221-011-2772-2
Abstract: The production of accurate motor actions requires successful extraction of relevant information about the target of that action. By the same token, it also requires the successful exclusion of potentially distracting, irrelevant information. This study sought to determine the impact of transient visual distractions on performance in an anticipatory timing task, in particular the temporal and spatial relationship between distractor and target at which maximal distraction occurs. The results support the notion of a critical temporal and spatial window of distraction which provides insight into the visuomotor processes underlying distraction.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.ACTPSY.2010.04.009
Abstract: Time constraints in ball sports encourage players to take advantage of any relevant advance information available to prepare their actions. Advance information, therefore, can serve to prime movement parameters (e.g. movement direction) and reduce the amount of time required to prepare the upcoming movement. Regularly, however, players face situations in which the information used to prepare the action turns out to be outdated just prior to movement initiation and the prepared action needs to be changed as soon as possible. The aim of the experiment presented here was to determine whether the priming effect, generally reported for reaction time tasks, could be generalised to interceptive actions. A secondary aim was to examine the strategies employed by the participants to cope with valid, invalid, or no advance information. The results indicate that, when available, the participants used advance information to prepare their movements. More specifically, in comparison with valid advance information, hit rate and spatial accuracy were reduced when the participants had no advance information and were even smaller when the information conveyed was invalid. The results also suggest that in the absence of valid advance information, the strategies employed to intercept the moving target were tuned to the time remaining until the interception was due to occur.
Publisher: Wiley
Date: 07-02-2023
DOI: 10.1111/PSYP.14267
Abstract: During preparation for action, the presentation of loud acoustic stimuli (LAS) can trigger movements at very short latencies in a phenomenon called the StartReact effect. It was initially proposed that a special, separate subcortical mechanism that bypasses slower cortical areas could be involved. We sought to examine the evidence for a separate mechanism against the alternative that responses to LAS can be explained by a combination of stimulus intensity effects and preparatory states. To investigate whether cortically mediated preparatory processes are involved in mediating reactions to LAS, we used an auditory reaction task where we manipulated the preparation level within each trial by altering the conditional probability of the imperative stimulus. We contrasted responses to non‐intense tones and LAS and examined whether cortical activation and subcortical excitability and motor responses were influenced by preparation levels. Increases in preparation levels were marked by gradual reductions in reaction time (RT) coupled with increases in cortical activation and subcortical excitability – at both condition and trial levels. Interestingly, changes in cortical activation influenced motor and auditory but not visual areas – highlighting the widespread yet selective nature of preparation. RTs were shorter to LAS than tones, but the overall pattern of preparation level effects was the same for both stimuli. Collectively, the results demonstrate that LAS responses are indeed shaped by cortically mediated preparatory processes. The concurrent changes observed in brain and behavior with increasing preparation reinforce the notion that preparation is marked by evolving brain states which shape the motor system for action.
Publisher: Wiley
Date: 26-11-2020
DOI: 10.1111/PSYP.13730
Publisher: Springer Science and Business Media LLC
Date: 30-06-2009
DOI: 10.1007/S00221-009-1916-0
Abstract: Two experiments aimed to provide an estimate of the last moment at which visual information needs to be obtained in order for it to be used to initiate execution of an interceptive movement or to withhold execution of such a movement. In experiment 1, we sought to estimate the minimum time required to suppress the movement when the participants were first asked to intercept a moving target. In experiment 2, we sought to determine the minimum time required to initiate an interceptive movement when the participants were initially asked to keep stationary. Participants were trained to hit moving targets using movements of a pre-specified duration. This permitted an estimate of movement onset (MO) time. In both experiments the requirement to switch from one prepared course of action to the other was indicated by changing the colour of the moving target at times prior to the estimated MO. The results of the experiments showed that the decision to execute or suppress the interception must be made no less than about 200 ms before MO.
Publisher: American Physiological Society
Date: 03-2011
Abstract: To intercept rapidly moving objects, people must predict the right time to initiate their actions. The timing of movement initiation in interceptions is thought to be determined when a perceptual variable specifying time to contact reaches a criterion value. If a response needs to be aborted, the performer must make a decision before this moment. It has been recently shown that the minimal time to suppress an anticipatory action takes longer during motion extrapolation than during continuous visual information. In experiment 1, we sought to determine whether or not the availability of visual information would 1) affect the latency to inhibit an anticipatory action, and 2) modulate the level of excitability in the motor cortex (M1). The behavioral results showed that the absence of visual information prolonged the latency to stop the movement as previously reported. The neurophysiological data indicated that corticospinal excitability levels were affected by the availability of visual information. In experiment 2, we sought to verify whether corticospinal excitability levels would also differ between the two visual conditions when the task did not involve response suppression. The results of experiment 2 indicated that excitability levels did not differ between visual conditions. Overall, our findings indicated that the buildup of motor activation can also play a role in determining different latencies to inhibit an anticipatory action. They also suggest that the buildup of motor activation in the corticospinal pathways can be strategically modulated to the requirements of the task during continuous visual information.
Publisher: Wiley
Date: 02-12-2022
DOI: 10.1111/EJN.13769
Abstract: Skills learned through practice with one limb can often be transferred to the untrained limb. In the present report, we sought to determine whether movement direction biases, acquired through repeated movement with one limb, transfer to the untrained limb. In order to do so, we asked participants to perform synchronized bilateral contractions of muscles in both wrists, followed by the unilateral contraction of muscles in one wrist. In four experiments, we manipulated the position of the unilateral target to create use-dependent directional biases changed the direction of the cursor in relation to the wrist movement to control for attentional biases and sought to induce directional biases with both right and left unilateral movements. The results showed clear movement-related biases for the wrist that performed unilateral contractions, but no evidence that movement-related bias transferred to the opposite limb during bilateral action. Thus, motor preparation and execution of unilateral contractions does not affect the direction of movement made by the opposite limb during subsequent bilateral contractions.
Publisher: Springer Science and Business Media LLC
Date: 21-08-2014
DOI: 10.1007/S00221-014-4074-Y
Abstract: The presentation of an unexpected and loud auditory stimulus (LAS) during action preparation can trigger movement onset much sooner than normal. Recent research has attributed this effect to the activation of reticulospinal connections to the target muscles. To our knowledge, no studies have investigated the effects of LAS presentation in tasks requiring the simultaneous activation of muscles with different connectivity to motor areas of the brain. Here, we sought to establish the importance of muscle connectivity by asking participants to contract the orbicularis oris and abductor pollicis brevis muscles simultaneously. A LAS was randomly presented at 200 ms prior to the expected time of movement onset in an anticipatory timing task. We show that muscles controlled via bulbar connections to reticular formation can be triggered early by sound as much as muscles with spinal connections to the reticular formation.
Publisher: American Psychological Association (APA)
Date: 08-2018
DOI: 10.1037/XHP0000529
Abstract: Previous research on skill acquisition has shown that learners seem to prefer receiving knowledge of results (KR) about those trials in which they have performed more accurately. In the present study, we assessed whether this preference leads to an advantage in terms of skill acquisition, transfer, and retention of their capacity to extrapolate the motion of decelerating objects during periods of visual occlusion. Instead of questionnaires, we adopted a more direct approach to investigate learners' preferences for KR. Participants performed 90 trials of a motion extrapolation task (acquisition phase) in which, every three trials, they could decide between receiving KR about their best or worst performance. Retention and transfer tests were carried out 24 hr after the acquisition phase, without KR, to examine the effects of the self-selected KR on sensorimotor learning. Consistent with the current literature, a preference for receiving KR about the most accurate performance was observed. However, participants' preferences were not consistent throughout the experiment as less than 10% (N = 40) selected the same type of KR in all their choices. Importantly, although preferred by most participants, KR about accurate performances had detrimental effects on skill acquisition, suggesting that learners may not always choose the KR that will maximize their learning experiences and skill retention. (PsycINFO Database Record
Publisher: Society for Neuroscience
Date: 06-02-2020
DOI: 10.1523/JNEUROSCI.1506-19.2020
Abstract: Traditional views of sensorimotor adaptation (i.e., adaptation of movements to perturbed sensory feedback) emphasize the role of automatic, implicit correction of sensory prediction errors. However, latent memories formed during sensorimotor adaptation, manifest as improved relearning (e.g., savings), have recently been attributed to strategic corrections of task errors (failures to achieve task goals). To dissociate contributions of task errors and sensory prediction errors to latent sensorimotor memories, we perturbed target locations to remove or enforce task errors during learning and/or test, with male/female human participants. Adaptation improved after learning in all conditions where participants were permitted to correct task errors, and did not improve whenever we prevented correction of task errors. Thus, previous correction of task errors was both necessary and sufficient to improve adaptation. In contrast, a history of sensory prediction errors was neither sufficient nor obligatory for improved adaptation. Limiting movement preparation time showed that the latent memories driven by learning to correct task errors take at least two forms: a time-consuming but flexible component, and a rapidly expressible, inflexible component. The results provide strong support for the idea that movement corrections driven by a failure to successfully achieve movement goals underpin motor memories that manifest as savings. Such persistent memories are not exclusively mediated by time-consuming strategic processes but also comprise a rapidly expressible but inflexible component. The distinct characteristics of these putative processes suggest dissociable underlying mechanisms, and imply that identification of the neural basis for adaptation and savings will require methods that allow such dissociations. SIGNIFICANCE STATEMENT Latent motor memories formed during sensorimotor adaptation manifest as improved adaptation when sensorimotor perturbations are reencountered. Conflicting theories suggest that this “savings” is underpinned by different mechanisms, including a memory of successful actions, a memory of errors, or an aiming strategy to correct task errors. Here we show that learning to correct task errors is sufficient to show improved subsequent adaptation with respect to naive performance, even when tested in the absence of task errors. In contrast, a history of sensory prediction errors is neither sufficient nor obligatory for improved adaptation. Finally, we show that latent sensorimotor memories driven by task errors comprise at least two distinct components: a time-consuming, flexible component, and a rapidly expressible, inflexible component.
Publisher: Cold Spring Harbor Laboratory
Date: 25-04-2020
DOI: 10.1101/2020.04.23.056929
Abstract: There has been much debate concerning whether startling sensory stimuli can activate a fast-neural pathway for movement triggering (StartReact) which is different from that of voluntary movements. Activity in sternocleidomastoid (SCM) electromyogram is suggested to indicate activation of this pathway. We evaluated whether SCM activity can accurately identify trials which may differ in their neurophysiological triggering and assessed the use of cumulative distribution functions (CDFs) of reaction time (RT) data to identify trials with the shortest RTs for analysis. Using recent datasets from the StartReact literature, we examined the relationship between RT and SCM activity. We categorised data into short/longer RT bins using CDFs and used linear mixed effects models to compare potential conclusions that can be drawn when categorising data on the basis of RT versus on the basis of SCM activity. The capacity of SCM to predict RT is task-specific, making it an unreliable indicator of distinct neurophysiological mechanisms. Classification of trials using CDFs is capable of capturing potential task- or muscle-related differences in triggering whilst avoiding the pitfalls of the traditional SCM activity based classification method. We conclude that SCM activity is not always evident on trials that show the early triggering of movements seen in the StartReact phenomenon. We further propose that a more comprehensive analysis of data may be achieved through the inclusion of CDF analyses. These findings have implications for future research investigating movement triggering as well as for potential therapeutic applications of StartReact.
Publisher: Elsevier BV
Date: 08-2013
DOI: 10.1016/J.VISRES.2013.05.009
Abstract: Many visual processes integrate information over protracted periods, a process known as temporal integration. One consequence of this is that objects that cast images that move across the retinal surfaces can generate blurred form signals, similar to the motion blur that can be captured in photographs taken with slow shutter speeds. Subjectively, retinal motion blur signals are suppressed from awareness, such that moving objects seem sharply defined. One suggestion has been that this subjective impression is due to humans not being able to distinguish between focussed and blurred moving objects. Contrary to this suggestion, here we report a novel illusion, and consequent experiments, that implicate a suppressive mechanism. We find that the apparent shape of circular moving objects can be distorted when their rear edges lag leading edges by ∼60 ms. Moreover, we find that sensitivity for detecting blur, and for discriminating between blur intensities, is uniformly worse for physical blurs added behind moving objects, as opposed to in-front. Also, it was easier to differentiate between slight and slightly greater physical blurs than it was to differentiate between slight blur and the absence of blur, both behind and in-front of moving edges. These 'dipper' functions suggest that blur signals must reach a threshold intensity before they can be detected, and that the relevant threshold is effectively elevated for blur signals trailing behind moving contours. In combination, these data suggest moving objects look sharply defined, at least in part, because of a functional adaptation that actively suppresses motion blur signals from awareness.
Publisher: Springer Science and Business Media LLC
Date: 07-06-2017
Publisher: Cambridge University Press (CUP)
Date: 09-06-2014
DOI: 10.1017/JGC.2014.12
Abstract: The literature indicates increasing evidence showing the benefits of classroom-based, universal preventive interventions for mental health and the link between social and emotional learning and academic performance. The FRIENDS program has been extensively tested and has showed promising results not only for preventing childhood anxiety, but also for improving students’ self-concept, social skills and coping skills. However, when it comes to communities in disadvantage, the results are mixed, with some studies reporting the need to include enhancements to the context in which the program is implemented to better support communities at risk. A combined intervention aiming to promote students’ social-emotional skills was piloted in a school located in a low socio-economic status area. Teachers received training to teach social and emotional skills for students and a resilience program for themselves. Students’ social-emotional outcomes were assessed at pre, post, 3 and 6 months following the intervention. Results showed that the intervention helped students to decrease their anxiety, and the intervention was well accepted by participants.
Publisher: American Physiological Society
Date: 15-02-2013
Abstract: Previous research using a loud acoustic stimulus (LAS) to investigate motor preparation in reaction time (RT) tasks indicates that responses can be triggered well in advance of the presentation of an imperative stimulus (IS). This is intriguing given that high levels of response preparation cannot be maintained for long periods (≈ 200 ms). In the experiments reported here we sought to assess whether response-related activation increases gradually over time in simple RT tasks. In experiment 1, a LAS was presented at different times just prior to the presentation of the IS to probe the level of activation for the motor response. In experiment 2, the same LAS was presented at different times after the presentation of the IS. The results provide evidence that response-related activation does increase gradually in anticipation of the IS, but it remains stable for a short time after this event. The data display a pattern consistent with the response being triggering by the LAS, rather than a reaction to the IS.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.NEULET.2010.03.027
Abstract: Pleasant and unpleasant emotional stimuli are frequently conceptualized as motivators for action. This notion was examined using focal transcranial magnetic stimulation (TMS). Ten healthy participants viewed pleasant, neutral, and unpleasant pictures from the International Affective Picture System (IAPS). During picture viewing, focal TMS was applied to the right motor cortex over the area innervating the first dorsal interosseous muscle of the left hand. Corticomotor excitability was larger while viewing negative pictures than while viewing neutral or positive images, as evidenced by greater motor evoked potentials. No difference was found between pleasant and neutral pictures. These results are consistent with models of emotion in which the neural networks underlying negative emotions have selective, direct connections to brain structures that mediate motor responses.
Publisher: SAGE Publications
Date: 09-01-2013
Abstract: Many activities, such as driving or playing sports, require simultaneous monitoring of multiple, often moving, objects. Such situations tap people’s ability to attend selected objects without tracking them with their eyes—this is known as attentional tracking. It has been established that attentional tracking can be affected by the physical speed of a moving target. In the experiments reported here, we showed that this effect is primarily due to apparent speeds, as opposed to physical speeds. We used sensory adaptation—in this case, prolonged exposure to adapting stimuli moving faster or slower than standard test stimuli—to modulate perceived speed. We found performance decrements and increments for apparently sped and slowed test stimuli when participants attempted attentional tracking. Our data suggest that both perceived speed and the acuity of attention for moving objects reflect a ratio of responses in low-pass and band-pass temporal-frequency channels in human vision.
Publisher: American Physiological Society
Date: 02-2012
Abstract: To intercept or avoid moving objects successfully, we must compensate for the sensorimotor delays associated with visual processing and motor movement. Although straightforward in the case of constant velocity motion, it is unclear how humans compensate for accelerations, as our visual system is relatively poor at detecting changes in velocity. Work on free-falling objects suggests that we are able to predict the effects of gravity, but this represents the most simple, limiting case in which acceleration is constant and motion linear. Here, we show that an internal model also predicts the effects of complex, varying accelerations when they result from lawful interactions with the environment. Participants timed their responses with the arrival of a ball rolling within a tube of various shapes. The pattern of errors indicates that participants were able to compensate for most of the effects of the ball acceleration (∼85%) within a relatively short practice (∼300 trials). Errors on catch trials in which the ball velocity was unexpectedly maintained constant further confirmed that participants were expecting the effect of acceleration induced by the shape of the tube. A similar effect was obtained when the visual scene was projected upside down, indicating that the mechanism of this prediction is flexible and not confined to ecologically valid interactions. These findings demonstrate that the brain is able to predict motion on the basis of prior experience of complex interactions between an object and its environment.
Publisher: American Psychological Association (APA)
Date: 2014
DOI: 10.1037/A0035362
Abstract: Illusory motion reversals (IMRs) can happen when looking at a repetitive pattern of motion, such as a spinning wheel. To date these have been attributed to either a form of motion aftereffect seen while viewing a moving stimulus or to the visual system taking discrete perceptual snapshots of continuous input. Here we present evidence that we argue is inconsistent with both proposals. First, we show that IMRs are driven by the adaptation of nondirectional temporal frequency tuned cells, which is inconsistent with the motion aftereffect account. Then we establish that the optimal frequency for inducing IMRs differs for color and luminance defined movement. These data are problematic for any account based on a constant rate of discrete perceptual s ling. Instead, we suggest IMRs result from a perceptual rivalry involving discrepant signals from a feature tracking analysis of movement and motion-energy based analyses. We do not assume that feature tracking relies on a discrete s ling of input at a fixed rate, but rather that feature tracking can (mis)match features at any rate less than a stimulus driven maximal resolution. Consistent with this proposal, we show that the critical frequency for inducing IMRs is dictated by the duty cycle of salient features within a moving pattern, rather than by the temporal frequency of luminance changes.
Publisher: Cold Spring Harbor Laboratory
Date: 04-12-2016
DOI: 10.1101/091397
Abstract: The cerebellum is known to be critically involved in sensorimotor adaptation. Changes in cerebellar function alter behaviour when compensating for sensorimotor perturbations, as shown by non-invasive stimulation of the cerebellum and studies involving patients with cerebellar degeneration. It is known, 24 however, that behavioural responses to sensorimotor perturbations reflect both explicit processes (such as volitional aiming to one side of a target to counteract a rotation of visual feedback) and implicit, error-driven updating of sensorimotor maps. The contribution of the cerebellum to these explicit and implicit processes remains unclear. Here, we examined the role of the cerebellum in sensorimotor adaptation to a 30° rotation of visual feedback of hand position during target-reaching, when the capacity to use explicit processes was manipulated by controlling movement preparation times. Explicit re-aiming was suppressed in one condition by requiring subjects to initiate their movements within 300ms of target presentation, and permitted in another condition by requiring subjects to wait approximately 1050ms after target presentation before movement initiation. Similar to previous work, applying anodal transcranial direct current stimulation (tDCS 1.5mA) to the right cerebellum during adaptation resulted in faster compensation for errors imposed by the rotation. After exposure to the rotation, we evaluated implicit remapping in no-feedback trials after providing participants with explicit knowledge that the rotation had been removed. Crucially, movements were more adapted in these no-feedback trials following cerebellar anodal tDCS than after sham stimulation in both long and short preparation groups. This suggests that cerebellar anodal tDCS increased implicit remapping during sensorimotor adaptation irrespective of preparation time constraints. This work shows that the cerebellum is critical in the formation of new visuomotor maps that correct perturbations in sensory feedback, both when explicit processes are suppressed and when allowed during sensorimotor adaptation.
Publisher: Cold Spring Harbor Laboratory
Date: 23-12-2016
DOI: 10.1101/096404
Abstract: Sensorimotor adaptation, or adaptation of movements to external perturbations, is thought to involve the primary motor cortex (M1). In addition to implicit error-driven remapping, explicit re-aiming strategies also contribute to sensorimotor adaptation. However, no studies to date have examined the role of M1 in implicit learning in isolation from explicit strategies. Because the application of explicit strategies requires time, it is possible to emphasise implicit learning by controlling the time available to prepare movement. Here, we examined the role of M1’s role in implicit adaptation to rotated visual feedback whilst suppressing the use of explicit re-aiming strategies by limiting movement preparation times to less than 350ms. Perturbing M1 activity via single-pulse TMS during adaptation to a 30 ° rotation of visual feedback did not alter the rate or extent of error compensation, but elicited poorer retention in post-adaptation trials with no perturbation. This work shows that M1 is critical in the retention of new visuomotor maps as a result of implicit adaptation to a perturbation in sensory feedback when strategic error correction processes are suppressed. Adaptation of movements to perturbations occurs through explicit and implicit processes. Here, explicit strategies were suppressed by shortening movement preparation time. Perturbing motor cortex (M1) with TMS selectively impaired retention but not acquisition of sensorimotor adaptation. M1 plays a crucial role in retention of sensorimotor adaptation obtained via implicit learning.
Publisher: Wiley
Date: 28-06-2026
DOI: 10.1111/EJN.15317
Abstract: Sensorimotor adaptation is an important part of our ability to perform novel motor tasks (i.e., learning of motor skills). Efforts to improve adaptation in healthy and clinical patients using non‐invasive brain stimulation methods have been hindered by inter‐in idual and intra‐in idual variability in brain susceptibility to stimulation. Here, we explore unpredictable loud acoustic stimulation as an alternative method of modulating brain excitability to improve sensorimotor adaptation. In two experiments, participants moved a cursor towards targets, and adapted to a 30º rotation of cursor feedback, either with or without unpredictable acoustic stimulation. Acoustic stimulation improved initial adaptation to sensory prediction errors in Study 1, and improved overnight retention of adaptation in Study 2. Unpredictable loud acoustic stimulation might thus be a potent method of modulating sensorimotor adaptation in healthy adults.
Publisher: American Physiological Society
Date: 12-08-2017
Abstract: During sensorimotor adaptation, implicit error-driven learning can be isolated from explicit strategy-driven reaiming by subtracting self-reported aiming directions from movement directions, or by restricting movement preparation time. Here, we compared the two methods. Restricting preparation times did not eliminate re-aiming but was sufficient to suppress reaiming during adaptation with widely distributed targets. The self-report method produced a discrepancy in implicit learning estimated by subtracting aiming directions and implicit learning measured in no-feedback trials.
Publisher: American Physiological Society
Date: 04-2019
Abstract: The characteristics of movements are strongly history-dependent. Marinovic et al. (Marinovic W, Poh E, de Rugy A, Carroll TJ. eLife 6: e26713, 2017) showed that past experience influences the execution of limb movements through a combination of temporally stable processes that are strictly use dependent and dynamically evolving and context-dependent processes that reflect prediction of future actions. Here we tested the basis of history-dependent biases for multiple spatiotemporal features of saccadic eye movements under two preparation time conditions (long and short). Twenty people performed saccades to visual targets. To prompt context-specific expectations of most likely target locations, 1 of 12 potential target locations was specified on ~85% of the trials and each remaining target was presented on ~1% trials. In long preparation trials participants were shown the location of the next target 1 s before its presentation onset, whereas in short preparation trials each target was first specified as the cue to move. Saccade reaction times and direction were biased by recent saccade history but according to distinct spatial tuning profiles. Biases were purely expectation related for saccadic reaction times, which increased linearly as the distance from the repeated target location increased when preparation time was short but were similar to all targets when preparation time was long. By contrast, the directions of saccades were biased toward the repeated target in both preparation time conditions, although to a lesser extent when the target location was precued (long preparation). The results suggest that saccade history affects saccade dynamics via both use- and expectation-dependent mechanisms and that movement history has dissociable effects on reaction time and saccadic direction. NEW & NOTEWORTHY The characteristics of our movements are influenced not only by concurrent sensory inputs but also by how we have moved in the past. For limb movements, history effects involve both use-dependent processes due strictly to movement repetition and processes that reflect prediction of future actions. Here we show that saccade history also affects saccade dynamics via use- and expectation-dependent mechanisms but that movement history has dissociable effects on saccade reaction time and direction.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2012
DOI: 10.1109/TOH.2011.66
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.NEUROSCIENCE.2017.02.016
Abstract: A loud acoustic stimulus (LAS) is often used as a tool to investigate motor preparation in simple reaction time (RT) tasks, where all movement parameters are known in advance. In this report, we used a LAS to examine direction specification in simple and choice RT tasks. This allowed us to investigate how the specification of movement direction unfolds during the preparation period. In two experiments, participants responded to the appearance of an imperative stimulus (IS) with a ballistic wrist force directed toward one of two targets. In probe trials, a LAS (120dBa) was delivered around the time of IS presentation. In Experiment 1, RTs in the simple RT task were faster when the LAS was presented, but the effect on the movement kinematics was negligible. In the Choice RT task, however, movement direction variability increased when the LAS was presented. In Experiment 2, when we primed movements toward one direction, our analyses revealed that the longer participants took to start a movement, the more accurate their responses became. Our results show not only that movement direction reprogramming occurs quickly and continuously, but also that LAS can be a valuable tool to obtain meaningful readouts of the motor system's preparatory state.
Publisher: Springer Science and Business Media LLC
Date: 2010
Publisher: Public Library of Science (PLoS)
Date: 07-07-2017
Publisher: S. Karger AG
Date: 2023
DOI: 10.1159/000529485
Abstract: b i Introduction: /i /b In in iduals with single-sided deafness (SSD), who are characterised by profound hearing loss in one ear and normal hearing in the contralateral ear, binaural input is no longer present. A cochlear implant (CI) can restore functional hearing in the profoundly deaf ear, with previous literature demonstrating improvements in speech-in-noise intelligibility with the CI. However, we currently have limited understanding of the neural processes involved (e.g., how the brain integrates the electrical signal produced by the CI with the acoustic signal produced by the normal hearing ear) and how modulation of these processes with a CI contributes to improved speech-in-noise intelligibility. Using a semantic oddball paradigm presented in the presence of background noise, this study aims to investigate how the provision of CI impacts speech-in-noise perception of SSD-CI users. b i Method: /i /b Task performance (reaction time, reaction time variability, target accuracy, subjective listening effort) and high density electroencephalography from twelve SSD-CI participants were recorded, while they completed a semantic acoustic oddball task. Reaction time was defined as the time taken for a participant to press the response button after stimulus onset. All participants completed the oddball task in three different free-field conditions with the speech and noise coming from different speakers. The three tasks were: (1) CI-On in background noise, (2) CI-Off in background noise, and (3) CI-On without background noise (Control). Task performance and electroencephalography data (N2N4 and P3b) were recorded for each condition. Speech in noise and sound localisation ability were also measured. b i Results: /i /b Reaction time was significantly different between all tasks with CI-On ( i M /i [ i SE /i ] = 809 [39.9] ms) having faster RTs than CI-Off ( i M /i [ i SE /i ] = 845 [39.9] ms) and Control ( i M /i [ i SE /i ] = 785 [39.9] ms) being the fastest condition. The Control condition exhibited significantly shorter N2N4 and P3b area latency compared to the other two conditions. However, despite these differences noticed in RTs and area latency, we observed similar results between all three conditions for N2N4 and P3b difference area. b i Conclusion: /i /b The inconsistency between the behavioural and neural results suggests that EEG may not be a reliable measure of cognitive effort. This rationale is further supported by different explanations used in past studies to explain N2N4 and P3b effects. Future studies should look to alternative measures of auditory processing (e.g., pupillometry) to gain a deeper understanding of the underlying auditory processes that facilitate speech-in-noise intelligibility.
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.BBR.2017.01.016
Abstract: Peripheral electrical stimulation (PES) modulates corticomotor excitability but its effect on motor performance has not been thoroughly investigated. The purpose of this study was to assess whether increases and/or decreases in corticomotor excitability, induced by PES, influenced motor performance using a visuomotor adaptation task. Three PES interventions (motor stimulation, sensory stimulation or sham) were delivered to the first dorsal interosseous (FDI) in 30 healthy participants matched for age, gender and handedness. Motor stimulation was applied to increase corticomotor excitability, sensory stimulation to decrease corticomotor excitability, while sham stimulation acted as a control. Corticomotor excitability was assessed using the litude of motor evoked potentials to transcranial magnetic stimulation recorded from FDI before and after each intervention. Following PES, participants completed a visuomotor adaptation task. This required participants to move a cursor accurately towards virtual targets with index finger movements when the cursor trajectory was rotated 30° counter clockwise. Performance was assessed as angular error (a measure of movement accuracy) and reaction time. The rate of visuomotor adaptation was greater following motor PES compared to sham, but not sensory, with no difference observed between sensory and sham. However, visuomotor adaptation performance overall (the total change in performance from beginning to end) was similar across intervention groups. These findings suggest that motor PES applied prior to task acquisition can facilitate the speed of adaptation.
Publisher: Cold Spring Harbor Laboratory
Date: 26-02-2018
DOI: 10.1101/263988
Abstract: Perturbations of sensory feedback evoke sensory prediction errors (discrepancies between predicted and actual sensory outcomes of movements), and reward prediction errors (discrepancies between predicted rewards and actual rewards). Sensory prediction errors result in obligatory remapping of the relationship between motor commands and predicted sensory outcomes. The role of reward prediction errors in sensorimotor adaptation is less clear. When moving towards a target, we expect to obtain the reward of hitting the target, and so we experience a reward prediction error if the perturbation causes us to miss it. These discrepancies between desired task outcomes and actual task outcomes, or “task errors”, are thought to drive the use of strategic processes to restore success, although their role is not fully understood. Here, we investigated the role of task errors in sensorimotor adaptation: during target-reaching, we either removed task errors by moving the target mid-movement to align with cursor feedback of hand position, or enforced task error by moving the target away from the cursor feedback of hand position. Removing task errors not only reduced the rate and extent of adaptation during exposure to the perturbation, but also reduced the amount of post-adaptation implicit remapping. Hence, task errors contribute to implicit remapping resulting from sensory prediction errors. This suggests that the system which implicitly acquires new sensorimotor maps via exposure to sensory prediction errors is also sensitive to reward prediction errors.
Publisher: Springer Science and Business Media LLC
Date: 16-04-2008
DOI: 10.1007/S00221-008-1360-6
Abstract: The interception of fast moving objects typically allows the object to be seen for only a short period of time. This limits the time available to prepare the movement. To deal with short preparation intervals, performers are likely to prepare a motor program in advance. Although motor preparation may begin before the target is seen, accuracy requires that certain program parameters are determined from observations of the target. In the experiments reported here we sought to determine the last moment at which information about the distance to move ( litude) can be incorporated into a program. We employed an empirical protocol that allowed us to examine whether new litude information is incorporated discretely or continuously into the program during short intervals prior to movement onset (MO)-the preparation interval. Participants were trained to hit targets at two different distances with movements of a specific duration (180 ms): targets were moving in "Experiment 1" and stationary in "Experiment 2". This method permitted an estimate of MO time. Preparation intervals were manipulated by delivering a stimulus cue for movement litude at varying times prior to the estimated MO. Results demonstrated that litude information could be effectively incorporated into the program provided the preparation interval was greater than about 200 ms. In addition, the results indicated that litude was specified predominantly in a discrete manner, though the number of responses directed towards a central default litude suggest that the distance between targets was near to a threshold for continuous specification.
Publisher: American Physiological Society
Date: 04-2022
Abstract: When intense sound is presented during light muscle contraction, inhibition of the corticomotoneuronal pathway is observed. During action preparation, this effect is reversed, with sound resulting in excitation of the corticomotoneuronal pathway. We investigated how the combined maintenance of a muscle contraction during preparation for a ballistic action impacts the magnitude of the facilitation of motor output by a loud acoustic stimulus (LAS), a phenomenon known as the StartReact effect. Participants executed ballistic wrist flexion movements and a LAS was presented simultaneously with the imperative signal in a subset of trials. We examined whether the force level or muscle used to maintain a contraction during preparation for the ballistic response impacted reaction time and/or the force of movements triggered by the LAS. These contractions were sustained either ipsilaterally or contralaterally to the ballistic response. The magnitude of facilitation by the LAS was greatest when low-force flexion contractions were maintained in the limb contralateral to the ballistic response during preparation. There was little change in facilitation when contractions recruited the contralateral extensor muscle or when they were sustained in the same limb that executed the ballistic response. We conclude that a larger network of neurons that may be engaged by a contralateral sustained contraction prior to initiation may be recruited by the LAS, further contributing to the motor output of the response. These findings may be particularly applicable in stroke rehabilitation, where engagement of the contralesional side may increase the benefits of a LAS to the functional recovery of movement.
Publisher: American Physiological Society
Date: 10-2016
Abstract: When we move, perturbations to our body or the environment can elicit discrepancies between predicted and actual outcomes. We readily adapt movements to compensate for such discrepancies, and the retention of this learning is evident as savings, or faster readaptation to a previously encountered perturbation. The mechanistic processes contributing to savings, or even the necessary conditions for savings, are not fully understood. One theory suggests that savings requires increased sensitivity to previously experienced errors: when perturbations evoke a sequence of correlated errors, we increase our sensitivity to the errors experienced, which subsequently improves error correction (Herzfeld et al. 2014). An alternative theory suggests that a memory of actions is necessary for savings: when an action becomes associated with successful target acquisition through repetition, that action is more rapidly retrieved at subsequent learning (Huang et al. 2011). In the present study, to better understand the necessary conditions for savings, we tested how savings is affected by prior experience of similar errors and prior repetition of the action required to eliminate errors using a factorial design. Prior experience of errors induced by a visuomotor rotation in the savings block was either prevented at initial learning by gradually removing an oppositely signed perturbation or enforced by abruptly removing the perturbation. Prior repetition of the action required to eliminate errors in the savings block was either deprived or enforced by manipulating target location in preceding trials. The data suggest that prior experience of errors is both necessary and sufficient for savings, whereas prior repetition of a successful action is neither necessary nor sufficient for savings.
Publisher: Elsevier BV
Date: 05-2014
Publisher: Wiley
Date: 04-09-2015
DOI: 10.1111/PSYP.12540
Abstract: The presentation of a loud acoustic stimulus during the preparation of motor actions can both speed movement initiation and increase response vigor. Several recent studies have explored this phenomenon as a means to investigate the mechanisms and neural correlates of movement preparation. Here, we sought to determine the generality of this effect across sensory modalities, and in particular whether unexpected somatosensory stimulation can facilitate movements in a manner similar to loud sounds. We show that electric and acoustic stimuli can be similarly effective in inducing the early release of motor actions, in both reaction time and anticipatory timing tasks. Consistent with recent response activation models of motor preparation, we also demonstrate that increasing the intensity of electric stimuli induces both progressive decreases in reaction time and increases in response vigor. Additionally, we show that the early release of motor actions can be induced by electric stimuli targeting predominantly either muscle afferents or skin afferents. Finally, we show that simultaneous acoustic and electric stimulation leads to earlier releases of anticipatory actions than either unimodal stimulus. These findings may lead to new avenues for experimental and clinical exploitation of the effects of accessory sensory information on movement preparation and initiation.
Publisher: Wiley
Date: 25-10-2013
Publisher: Elsevier BV
Date: 2009
DOI: 10.1016/J.BRAINRES.2008.11.001
Abstract: We report results from four experiments that examined performance of an interceptive task that restricted movement of the hand and moving target to a horizontal plane. The task required accurate control over both where and when interception takes place. Three experiments studied the effects of four independent variables: target speed, target size, manipulandum size and movement litude. For small litude movements, small, fast targets were hit harder than larger slower ones and targets were hit harder with smaller manipulanda movement time (MT) was unaffected by target size, but was shorter when the manipulandum was smaller. For larger litude movements, smaller, faster targets were also hit harder, but MTs tended to be greater when targets were smaller. The results support the idea that MT and peak movement speed can be independently controlled to some degree in order to meet the accuracy demands of the task. Analysis of the task showed that spatial and temporal accuracy demands are interdependent, indicating that the spatial and temporal variable errors should covary such that increases in one are accompanied by decreases in the other. This can be tested if there is no variation in interception location which was not the case in the first three experiments. In a final experiment variation in interception location was restricted by requiring that the target be struck through an aperture. Both spatial and temporal variable errors could be estimated. As predicted, it was found that when spatial errors were small, temporal errors were large.
Publisher: Cold Spring Harbor Laboratory
Date: 27-04-2021
DOI: 10.1101/2021.04.26.441384
Abstract: Shortly before movement initiation, the corticospinal system undergoes a transient suppression. This phenomenon has been observed across a range of motor tasks, suggesting that it may be a obligatory component of movement preparation. We probed whether this was also the case when the urgency to perform a motor action was high, in a situation where little time was available to engage in preparatory processes. We controlled the urgency of an impending motor action by increasing or decreasing the foreperiod duration in an anticipatory timing task. Transcranial magnetic stimulation (TMS experiment one) or a loud acoustic stimulus (LAS experiment two) were used to examine how corticospinal and subcortical excitability were modulated during motor preparation. Preparatory inhibition of the corticospinal tract was absent when movement urgency was high, though motor actions were initiated on time. In contrast, subcortical circuits were progressively inhibited as the time to prepare increased. Interestingly, movement force and vigour were reduced by both TMS and the LAS when movement urgency was high, and enhanced when movement urgency was low. Our findings indicate that preparatory inhibition may not be a obligatory component of motor preparation. The behavioural effects we observed in the absence of preparatory inhibition were induced by both TMS and the LAS, suggesting that accessory sensory stimulation may disrupt motor output when such stimulation is presented in the absence of preparatory inhibition. We conclude that preparatory inhibition may be an adaptive strategy which can serve to protect the prepared motor action from external interference.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.NEULET.2016.03.009
Abstract: There has been increasing interest in the use of loud acoustic stimulation (LAS) to gain insight into the preparation and initiation of motor actions. Typically, LAS presented during movement preparation in healthy participants culminates in the earlier than normal initiation of the prepared movement and an increase in the magnitude of the response. Recent reports have shown LAS can also facilitate movement in chronic stroke survivors. This suggests that current therapies for motor recovery after stroke might benefit from employing such alternate methods of triggering movement. In this study we sought to test a new way to facilitate motor actions that could be of relevance in clinical settings. Five in iduals with chronic motor impairments due to stroke and eight healthy young adults performed a functional reaching task in response to a visual go-signal. On 30% of the trials, LAS or electric stimuli (collectively, sensory stimuli) were unexpectedly presented in synchrony with the go-signal. Both healthy and stroke participants reacted with shorter latencies and executed faster responses when sensory stimulation was synchronized with the go-signal. We have replicated previous findings showing acoustic stimuli can aid movement execution in chronic stroke survivors and demonstrated the same type of effect can be achieved using electric stimulation. Thus, these two types of sensory stimuli can be easily integrated with current devices available to assist people with stroke to engage in rehabilitation efforts.
Publisher: Hogrefe Publishing Group
Date: 2009
DOI: 10.1027/1618-3169.56.4.265
Abstract: When intercepting a moving target, accurate timing depends, in part, upon starting to move at the right moment. It is generally believed that this is achieved by triggering motor command generation when a visually perceived quantity such as the target’s time-to-arrival reaches a specific criterion value. An experimental method that could be used to determine the moment when this visual event happens was introduced by Whiting and coworkers in the 1970s, and it involves occluding the vision of the target at different times prior to the time of movement onset (MO). This method is limited because the experimenter has no control over MO time. We suggest a method which provides the needed control by having people make interceptive movements of a specific duration. We tested the efficacy of this method in two experiments in which the accuracy of interception was examined under different occlusion conditions. In the first experiment, we examined the effect of changing the timing of an occlusion period (OP) of fixed duration (200 ms). In the second experiment, we varied the duration of the OP (180–430 ms) as well as its timing. The results demonstrated the utility of the proposed method and showed that performance deteriorated only when the participants had their vision occluded from 200 ms prior to MO. The results of Experiment 2 were able to narrow down the critical interval to trigger the interceptive action to within the period from 200 to 150 ms prior to MO, probably closer to 150 ms. In addition, the results showed that the execution of brief interceptive movements (180 ms) was not affected by the range of OPs used in the experiments. This indicates that the whole movement was prepared in advance and triggered by a visual stimulus event that occurred at about 150 ms before onset.
Publisher: Elsevier BV
Date: 06-2020
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.NEUROSCIENCE.2018.10.008
Abstract: Motor actions can be released much sooner than normal when the go-signal is of very high intensity (>100 dBa). Although statistical evidence from in idual studies has been mixed, it has been assumed that sternocleidomastoid (SCM) muscle activity could be used to distinguish between two neural circuits involved in movement triggering. We summarized meta-analytically the available evidence for this hypothesis, comparing the difference in premotor reaction time (RT) of actions where SCM activity was elicited (SCM+ trials) by loud acoustic stimuli against trials in which it was absent (SCM- trials). We found ten studies, all reporting comparisons between SCM+ and SCM- trials. Our mini meta-analysis showed that premotor RTs are faster in SCM+ than in SCM- trials, but the effect can be confounded by the variability of the foreperiods employed. We present experimental data showing that foreperiod predictability can induce differences in RT that would be of similar size to those attributed to the activation of different neurophysiological pathways to trigger prepared actions. We discuss plausible physiological mechanisms that would explain differences in premotor RTs between SCM+ and SCM- trials.
Publisher: Wiley
Date: 18-08-2021
DOI: 10.1113/JP281849
Abstract: Suppression of corticospinal excitability is reliably observed during preparation for a range of motor actions, leading to the belief that this preparatory inhibition is a physiologically obligatory component of motor preparation. The neurophysiological function of this suppression is uncertain. We restricted the time available for participants to engage in preparation and found no evidence for preparatory inhibition. The function of preparatory inhibition can be inferred from our findings that sensory stimulation can disrupt motor output in the absence of preparatory inhibition, but enhance motor output when inhibition is present. These findings suggest preparatory inhibition may be a strategic process which acts to protect prepared actions from external interference. Our findings have significant theoretical implications for preparatory processes. Findings may also have a pragmatic benefit in that acoustic stimulation could be used therapeutically to facilitate movement, but only if the action can be prepared well in advance. Shortly before movement initiation, the corticospinal system undergoes a transient suppression. This phenomenon has been observed across a range of motor tasks, suggesting that it may be an obligatory component of movement preparation. We probed whether this was also the case when the urgency to perform a motor action was high, in a situation where little time was available to engage in preparatory processes. We controlled the urgency of an impending motor action by increasing or decreasing the foreperiod duration in an anticipatory timing task. Transcranial magnetic stimulation (TMS experiment 1) or a loud acoustic stimulus (LAS experiment 2) were used to examine how corticospinal and subcortical excitability were modulated during motor preparation. Preparatory inhibition of the corticospinal tract was absent when movement urgency was high, though motor actions were initiated on time. In contrast, subcortical circuits were progressively inhibited as the time to prepare increased. Interestingly, movement force and vigour were reduced by both TMS and the LAS when movement urgency was high, and enhanced when movement urgency was low. These findings indicate that preparatory inhibition may not be an obligatory component of motor preparation. The behavioural effects we observed in the absence of preparatory inhibition were induced by both TMS and the LAS, suggesting that accessory sensory stimulation may disrupt motor output when such stimulation is presented in the absence of preparatory inhibition. We conclude that preparatory inhibition may be an adaptive strategy which can serve to protect the prepared motor action from external interference.
Publisher: Cold Spring Harbor Laboratory
Date: 15-03-2022
DOI: 10.1101/2022.03.13.484179
Abstract: Chronic pain is associated with dysfunctional cortical excitability. Research has identified altered intracortical motor cortex excitability in Chronic Lower Back Pain (CLBP). However, research identifying the specific intracortical changes underlying CLBP has been met with inconsistent findings. In the present case-control study, we examined intracortical excitability of the primary motor cortex using transcranial magnetic stimulation (TMS) in in iduals with CLBP. Twenty participants with CLBP ( M age = 54.45 years, SD age = 15.89 years) and 18 age- and gender-matched, pain-free controls ( M = 53.83, SD = 16.72) were included in this study. TMS was applied to the hand motor area of the right hemisphere and motor evoked potentials (MEPs) were recorded from the first dorsal interosseous muscle of the contralateral hand. Resting motor threshold (rMT) and MEP litude were measured using single-pulse stimulation. Short intracortical inhibition (SICI) and intracortical facilitation (ICF) were assessed using paired-pulse stimulation. In iduals with CLBP had significantly higher rMT (decreased corticospinal excitability) and reduced ICF compared to controls. No significant differences were found in MEP litude and SICI. These findings add to the growing body of evidence that CLBP is associated with deficits in intracortical modulation involving glutamatergic mechanisms. This article reports chronic lower back pain is associated with changes in intracortical excitability, specifically reduced intracortical facilitation. Furthermore, the imbalance between facilitation and inhibition may be related to pain intensity. These findings may help clinicians in the treatment of chronic pain with an increased focus on using neuromodulation techniques, targeting maladaptive intracortical facilitation, as a potential therapeutic tool in chronic pain.
Publisher: Cold Spring Harbor Laboratory
Date: 21-10-2016
DOI: 10.1101/082420
Abstract: When sensory feedback is perturbed, accurate movement is restored by a combination of implicit processes and deliberate re-aiming to strategically compensate for errors. Here, we directly compare two methods used previously to dissociate implicit from explicit learning on a trial-by-trial basis: 1) asking participants to report the direction that they aim their movements, and contrasting this with the directions of the target and the movement that they actually produce, 2) manipulating movement preparation time. By instructing participants to re-aim without a sensory perturbation, we show that re-aiming is possible even with the shortest possible preparation times, particularly when targets are narrowly distributed. Nonetheless, re-aiming is effortful and comes at the cost of increased variability, so we tested whether constraining preparation time is sufficient to suppress strategic re-aiming during adaptation to visuomotor rotation with a broad target distribution. The rate and extent of error reduction under preparation time constraints were similar to estimates of implicit learning obtained from self-report without time pressure, suggesting that participants chose not to apply a re-aiming strategy to correct visual errors under time pressure. Surprisingly, participants who reported aiming directions showed less implicit learning according to an alternative measure, obtained during trials performed without visual feedback. This suggests that the process of reporting can affect the extent or persistence of implicit learning. The data extend existing evidence that restricting preparation time can suppress explicit re-aiming, and provide an estimate of implicit visuomotor rotation learning that does not require participants to report their aiming directions. During sensorimotor adaptation, implicit, error-driven learning can be isolated from explicit strategy-driven re-aiming by subtracting self-reported aiming directions from movement directions, or by restricting movement preparation time. Here, we compared the two methods. Restricting preparation times did not eliminate re-aiming, but was sufficient to suppress reaiming during adaptation with widely-distributed targets. The self-report method produced a discrepancy in implicit learning estimated by subtracting aiming directions, and implicit learning measured in no-feedback trials.
Publisher: Cold Spring Harbor Laboratory
Date: 03-07-2018
DOI: 10.1101/360297
Abstract: Motor actions can be released much sooner than normal when the go-signal is of very high intensity ( 100dBa). Although statistical evidence from in idual studies has been mixed, it has been assumed that sternocleidomastoid (SCM) muscle activity could be used to distinguish between two neural circuits involved in movement triggering. We summarized meta-analytically the available evidence for this hypothesis, comparing the difference in premotor reaction time (RT) of actions where SCM activity was elicited (SCM+ trials) by loud acoustic stimuli against trials in which it was absent (SCM- trials). We found ten studies, all reporting comparisons between SCM+ and SCM- trials. Our mini meta-analysis showed that premotor RTs are faster in SCM+ than in SCM- trials. We also present experimental data showing the effects of foreperiod predictability can induce differences in RT that would be of similar size to those attributed to the activation of different neurophysiological pathways to trigger prepared actions. We discuss plausible physiological mechanisms that would explain differences in premotor RTs between SCM+ and SCM-trials.
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.HUMOV.2015.05.003
Abstract: A loud auditory stimulus (LAS) presented together with an imperative stimulus during preparation for motor actions can speed their initiation. The effects of LAS on corticospinal excitability (CSE), however, depend on the state of preparation of the motor system for action. CSE also depends on the brain hemisphere controlling the responding limb. Usually, CSE is increased just before movement onset in the hemisphere controlling the movement and inhibited on the other side. This study investigated the impact of LAS on CSE of the contralateral and ipsilateral hemispheres, while participants prepared for a voluntary abduction of the index finger. In Experiment 1, we attempted to identify the pattern of modulation of the ipsilateral cortex (resting side) by determining the time course of corticospinal changes in anticipatory timing actions using transcranial magnetic stimulation. In Experiment 2, we investigated the impact of LAS on the ipsilateral and contralateral CSE during anticipatory preparation. Results found no modulation of ipsilateral CSE during preparation, but indicate an increase in CSE after EMG onset on the acting limb. Moreover, we found that LAS presentation increased CSE on the contralateral side (active side).
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.VISRES.2016.04.005
Abstract: Ballistic eye movements, or saccades, present a major challenge to the visual system. They generate a rapid blur of movement across the surface of the retinae that is rarely consciously seen, as awareness of input is suppressed around the time of a saccade. Saccades are also associated with a number of perceptual distortions. Here we are primarily interested in a saccade-induced illusory reversal of apparent temporal order. We examine the apparent order of transient targets presented around the time of saccades. In agreement with previous reports, we find evidence for an illusory reversal of apparent temporal order when the second of two targets is presented during a saccade - but this is only apparent for some observers. This contrasts with the apparent salience of targets presented during a saccade, which is suppressed for all observers. Our data suggest that separable processes might underlie saccadic suppressions of salience and saccade-induced reversals of apparent order. We suggest the latter arises when neural transients, normally used for timing judgments, are suppressed due to a saccade - but that this is an insufficient pre-condition. We therefore make the further suggestion, that the loss of a neural transient must be coupled with a specific inferential strategy, whereby some people assume that when they lack a clear impression of event timing, that event must have happened less recently than alternate events for which they have a clear impression of timing.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.VISRES.2012.03.010
Abstract: Visual information is an essential guide when interacting with moving objects, yet it can also be deceiving. For instance, motion can induce illusory position shifts, such that a moving ball can seem to have bounced past its true point of contact with the ground. Some evidence suggests illusory motion-induced position shifts bias pointing tasks to a greater extent than they do perceptual judgments. This, however, appears at odds with other findings and with our success when intercepting moving objects. Here we examined the accuracy of interceptive movements and of perceptual judgments in relation to simulated bounces. Participants were asked to intercept a moving disc at its bounce location by positioning a virtual paddle, and then to report where the disc had landed. Results showed that interceptive actions were accurate whereas perceptual judgments were inaccurate, biased in the direction of motion. Successful interceptions necessitated accurate information concerning both the location and timing of the bounce, so motor planning evidently had privileged access to an accurate forward model of bounce timing and location. This would explain why people can be accurate when intercepting a moving object, but lack insight into the accurate information that had guided their actions when asked to make a perceptual judgment.
Publisher: Hogrefe Publishing Group
Date: 12-2010
DOI: 10.1027/1618-3169/A000034
Abstract: In fastball sports such as baseball and tennis people are required to produce accurate responses following brief observations of the ball. This limits the time available to prepare the movement. To cope with constrained viewing periods which precede the interception of fast approaching balls, performers are likely to prepare their responses in advance. Although motor preparation may begin before the moving object is seen, accuracy requires that certain program parameters are determined from observations of the target. The aim of the experiment reported here was to determine the last moment at which information about the direction of the target can be incorporated into a motor program. The empirical protocol used in this study allowed us to examine whether new direction information is incorporated discretely or continuously into the program during short intervals prior to movement onset (MO) – the preparation interval. Participants were trained to hit moving targets at two directions with movements of a specific duration (180 ms). This method permitted an estimate of MO. Preparation intervals were controlled by issuing a stimulus cue for movement direction at various times prior to the estimated MO. Results showed that direction information could be fully incorporated into the program with a preparation interval as brief as 250 ms. In addition, the results indicated that direction was specified predominantly in a discrete fashion even at short preparation intervals.
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.NEUROSCIENCE.2015.01.050
Abstract: Research on motor imagery and action observation has become increasingly important in recent years particularly because of its potential benefits for movement rehabilitation and the optimization of athletic performance (Munzert et al., 2009). Motor execution, motor imagery, and action observation have been shown to rely largely on a similar neural network in motor and motor-related cortical areas (Jeannerod, 2001). Given that motor imagery is a covert stage of an action and its characteristics, it has been assumed that modifying the motor task in terms of, for ex le, effort will impact neural activity. With this background, the present study examined how different force requirements influence corticospinal excitability (CSE) and intracortical facilitation during motor imagery and action observation of a repetitive movement (dynamic force production). Participants were instructed to kinesthetically imagine or observe an abduction/adduction movement of the right index finger that differed in terms of force requirements. Trials were carried out with single- or paired-pulse transcranial magnetic stimulation. Surface electromyography was recorded from the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM). As expected, results showed a significant main effect on mean peak-to-peak motor-evoked potential (MEP) litudes in FDI but no differences in MEP litudes in ADM muscle. Participants' mean peak-to-peak MEPs increased when the force requirements (movement effort) of the imagined or observed action were increased. This reveals an impact of the imagined and observed force requirements of repetitive movements on CSE. It is concluded that this effect might be due to stronger motor neuron recruitment for motor imagery and action observation with an additional load. That would imply that the modification of motor parameters in movements such as force requirements modulates CSE.
Publisher: Brill
Date: 18-10-2023
Start Date: 2016
End Date: 2018
Funder: Australian Research Council
View Funded ActivityStart Date: 2012
End Date: 2015
Funder: Australian Research Council
View Funded ActivityStart Date: 2018
End Date: 2020
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2012
End Date: 05-2015
Amount: $375,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2016
End Date: 03-2020
Amount: $301,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2018
End Date: 12-2023
Amount: $339,000.00
Funder: Australian Research Council
View Funded Activity