ORCID Profile
0000-0002-5240-4790
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Psychology | Developmental Psychology and Ageing | Sensory Processes, Perception and Performance | Decision Making | Central Nervous System | Motor Control | Biological Psychology (Neuropsychology, Psychopharmacology, Physiological Psychology) |
Expanding Knowledge in Psychology and Cognitive Sciences | Health Related to Ageing | Expanding Knowledge in the Medical and Health Sciences
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2012.06.024
Abstract: Human motor behaviour is continually modified on the basis of errors between desired and actual movement outcomes. It is emerging that the role played by the primary motor cortex (M1) in this process is contingent upon a variety of factors, including the nature of the task being performed, and the stage of learning. Here we used repetitive TMS to test the hypothesis that M1 is intimately involved in the initial phase of sensorimotor adaptation. Inhibitory theta burst stimulation was applied to M1 prior to a task requiring modification of torques generated about the elbow/forearm complex in response to rotations of a visual feedback display. Participants were first exposed to a 30° clockwise (CW) rotation (Block A), then a 60° counterclockwise rotation (Block B), followed immediately by a second block of 30° CW rotation (A2). In the STIM condition, participants received 20s of continuous theta burst stimulation (cTBS) prior to the initial A Block. In the conventional (CON) condition, no stimulation was applied. The overt characteristics of performance in the two conditions were essentially equivalent with respect to the errors exhibited upon exposure to a new variant of the task. There were however, profound differences between the conditions in the latency of response preparation, and the excitability of corticospinal projections from M1, which accompanied phases of de-adaptation and re-adaptation (during Blocks B and A2). Upon subsequent exposure to the A rotation 24h later, the rate of re-adaptation was lower in the stimulation condition than that present in the conventional condition. These results support the assertion that primary motor cortex assumes a key role in a network that mediates adaptation to visuomotor perturbation, and emphasise that it is engaged functionally during the early phase of learning.
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.CORTEX.2017.10.002
Abstract: When selecting actions based on visual warning stimuli (WS), corticospinal excitability (CSE) is initially suppressed, consistent with a neural mechanism to prevent premature release of the competing responses. Despite being implicated in between-hand movement selection and preparation, the role that interhemispheric inhibition (IHI) may play in this 'impulse control' mechanism is not known. Participants performed a warned, between-hand, choice reaction time (RT) task in which the informativeness of the WS (with regards to which hand would be required to respond) was manipulated. Transcranial magnetic stimulation (TMS) assessed CSE of the right primary motor cortex (M1) and IHI from left to right M1 with 10 (IHI10) and 40 (IHI40) msec interstimulus intervals during movement selection and preparation. Consistent with impulse control, CSE was initially suppressed prior to both left and right hand actions, irrespective of WS informativeness. Subsequent CSE increases occurred in the responding hand which were larger, and occurred earlier, following an informative WS. Importantly, these increases strongly predicted response times. In contrast to the generic CSE suppression, an informative WS permitted a hand-specific release of IHI10 in the responding hand, whereas IHI40 was released in both hands. As releases of IHI cannot explain a simultaneous suppression of CSE, this suggests several distinct movement preparation mechanisms are at play with IHI modulation occurring independently from impulse control. Notably, the findings support the notion that IHI10 and IHI40 between contralateral motor regions are mediated by discrete transcallosal pathways, and are differently modulated by specific motor and cognitive attributes of a rapid choice task.
Publisher: Public Library of Science (PLoS)
Date: 31-07-2019
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.NEUROBIOLAGING.2016.11.012
Abstract: Functional motor declines that often occur with advancing age-including reduced efficacy to learn new skills-can have a substantial impact on the quality of life. Recent studies using noninvasive brain stimulation indicate that priming the corticospinal system by lowering the threshold for the induction of long-term potentiation-like plasticity before skill training may facilitate subsequent skill learning. Here, we used "priming" protocol, in which we used transcranial direct current stimulation (tDCS) applying the cathode over the primary motor cortex (M1) before the anode placed over M1 during unimanual isometric force control training (FORCE
Publisher: Springer Science and Business Media LLC
Date: 05-08-2008
DOI: 10.1007/S00221-008-1513-7
Abstract: We investigated visuomotor adaptation using an isometric, target-acquisition task. Following trials with no rotation, two participant groups were exposed to a random sequence of 30 degrees clockwise (CW) and 60 degrees counter-clockwise (CCW) rotations, with (DUAL-CUE), or without (DUAL-NO CUE), colour cues that enabled each environment (non-rotated, 30 degrees CW and 60 degrees CCW) to be identified. A further three groups experienced only 30 degrees CW trials or only 60 degrees CCW trials (SINGLE rotation groups) in which each visuomotor mapping was again associated with a colour cue. During training, all SINGLE groups reduced angular deviations of the cursor path during the initial portion of the movements, indicating feedforward adaptation. Consistent with the view that the adaptation occurred automatically via recalibration of the visuomotor mapping (Krakauer et al. 1999), post-training aftereffects were observed, despite colour cues that indicated that no rotation was present. For the DUAL-CUE group, angular deviations decreased with training in the 60 degrees trials, but were unchanged in the 30 degrees trials, while for the DUAL-NO CUE group angular deviations decreased for the 60 degrees CW trials but increased for the 30 degrees CW trials. These results suggest that in a dual adaptation paradigm a colour cue can permit delineation of the two environments, with a subsequent change in behaviour resulting in improved performance in at least one of these environments. Increased reaction times within the training block, together with the absence of aftereffects in the post-training period for the DUAL-CUE group suggest an explicit cue-dependent strategy was used in an attempt to compensate for the rotations.
Publisher: American Physiological Society
Date: 2011
DOI: 10.1152/JAPPLPHYSIOL.00958.2010
Abstract: The phenomenon of cross-limb transfer, in which unilateral strength training can result in bilateral strength gains, has recently been tested for ballistic movements. Performance gains associated with repetitive motor practice, and the associated transfer, occur within a few minutes. In this study, young and older adults were trained to perform ballistic abductions of their dominant (right) index finger as quickly as possible. Performance was assessed bilaterally before, during, and after this training. Both groups exhibited large performance gains in the right hand as a result of training ( P 0.001 young 84% improvement, older 70% improvement), which were not significantly different between groups ( P = 0.40). Transcranial magnetic stimulation revealed that the performance improvements were accompanied by increases in excitability, together with decreases in intracortical inhibition, of the projections to both the trained muscle and the homologous muscle in the contralateral limb ( P 0.05). The young group also exhibited performance improvements as a result of cross-limb transfer in the left (untrained) hand ( P 0.005), equivalent to 75% of the performance increase in the trained hand. In contrast, there were no significant performance gains in the left hand for the older group ( P = 0.23). This was surprising given that the older group exhibited a significantly greater degree of mirror activity than the young group ( P 0.01) in the left first dorsal interosseus muscle (FDI) during right hand movements. Our findings suggest that older adults exhibit a reduced capacity for cross-limb transfer, which may have implications for motor rehabilitation programs after stroke.
Publisher: Springer Science and Business Media LLC
Date: 05-08-2010
DOI: 10.1007/S00221-010-2379-Z
Abstract: We investigated how volitional contractions affect interhemispheric inhibition (IHI) from the active to the passive hemisphere. Younger and older adults isometrically contracted their dominant thumb (abductor pollicis brevis, APB) to various force targets. In ballistic contraction trials, transcranial magnetic stimulation (TMS) was administered very shortly after the onset of APB activity. In tonic contraction trials, TMS was delivered while the target force was maintained. In control trials both thumbs remained quiescent. In all trials, a test stimulus (TS) was directed to the APB hotspot in the non-dominant hemisphere (130% left APB resting motor threshold, RMT). In half the trials, a conditioning stimulus (130% right APB RMT) was applied to the APB hotspot in the dominant hemisphere 10 ms prior to the TS. Targeted ballistic contractions of the right APB were found to modulate (increase) IHI measured in the left APB, as previously reported for tonic contractions. Furthermore, the extent of the IHI increase was found to scale with the strength of the contralateral ballistic or tonic contraction. Less pronounced, but statistically significant, IHI increases were also observed in the left abductor digiti minimi and extensor carpi radialis during right APB contraction. For these muscles, however, the extent of the IHI modulation was independent of APB contraction strength. The capacity to modulate inhibition during contractions was unaffected by advancing age. During volitional actions, the ability to modulate IHI most adaptively in the homologous muscle of the resting limb may contribute to the prevention of mirror movements.
Publisher: Springer Science and Business Media LLC
Date: 14-10-2009
DOI: 10.1007/S00221-009-2029-5
Abstract: We investigated how ballistic contractions of the left thumb affect the excitability of the ipsilateral motor cortex using transcranial magnetic stimulation (TMS). TMS was applied at the motor hotspot for the right abductor pollicis brevis (APB) muscle. In 'self-triggered' trials, participants made targeted, isometric, contractions of the left APB. The right APB was either relaxed or maintained a tonic contraction. TMS was administered as soon as possible after electromyographic onset in the left APB. In 'control' trials, the left thumb remained quiescent and TMS was triggered by the computer. In each condition, 20-24 trials were conducted. Half these trials involved a single test stimulus, TS (130% APB resting motor threshold, RMT). In the other trials, short-interval intracortical inhibition (SICI) was investigated by applying a conditioning stimulus (70% APB RMT) 3 ms prior to the TS. SICI ratios were not significantly different in self-triggered and control trials. However, when the right APB was active, significantly shorter silent periods (SPs) were observed in self-triggered trials when compared with control trials. Our results support the view that SICI and SP are mediated by different inhibitory circuits, and that ipsilateral GABA(B)-ergic circuits (assessed by SP), but not GABA(A)-ergic circuits (assessed by SICI), are affected in the period immediately following voluntary ballistic contractions.
Publisher: Springer Science and Business Media LLC
Date: 15-10-2009
DOI: 10.1007/S00221-009-2025-9
Abstract: We investigated the role of visual feedback of task performance in visuomotor adaptation. Participants produced novel two degrees of freedom movements (elbow flexion-extension, forearm pronation-supination) to move a cursor towards visual targets. Following trials with no rotation, participants were exposed to a 60 degrees visuomotor rotation, before returning to the non-rotated condition. A colour cue on each trial permitted identification of the rotated/non-rotated contexts. Participants could not see their arm but received continuous and concurrent visual feedback (CF) of a cursor representing limb position or post-trial visual feedback (PF) representing the movement trajectory. Separate groups of participants who received CF were instructed that online modifications of their movements either were, or were not, permissible as a means of improving performance. Feedforward-mediated performance improvements occurred for both CF and PF groups in the rotated environment. Furthermore, for CF participants this adaptation occurred regardless of whether feedback modifications of motor commands were permissible. Upon re-exposure to the non-rotated environment participants in the CF, but not PF, groups exhibited post-training aftereffects, manifested as greater angular deviations from a straight initial trajectory, with respect to the pre-rotation trials. Accordingly, the nature of the performance improvements that occurred was dependent upon the timing of the visual feedback of task performance. Continuous visual feedback of task performance during task execution appears critical in realising automatic visuomotor adaptation through a recalibration of the visuomotor mapping that transforms visual inputs into appropriate motor commands.
Publisher: Center for Open Science
Date: 08-2022
Abstract: Response-selective stopping requires cancellation of only one component of a multicomponent action. While research has investigated how delays to the continuing action components (‘stopping interference’) can be attenuated by way of contextual cues of the specific stopping demands (‘foreknowledge’), little is known of the underlying neural mechanisms. Twenty-seven healthy young adults undertook a multicomponent stop-signal task. On 2/3rd of trials, participants responded to an imperative (go) stimulus (IS) with simultaneous button presses using their left and right index fingers. On the remaining 1/3rd of trials, the IS was followed by a stop-signal requiring cancellation of only the left, or right, response. To manipulate foreknowledge of stopping demands, a cue preceded the IS that informed participants which hand might be required to stop (proactive) or provided no such information (reactive). Transcranial magnetic stimulation (TMS) assessed corticospinal excitability (CSE) as well as short- and long-interval interhemispheric inhibition (SIHI, LIHI) between the primary motor cortices. Proactive cues reduced, but did not eliminate, stopping interference relative to the reactive condition. Relative to TMS measures at cue onset, decreases in CSE (both hands and both cue conditions) and LIHI (both hands, proactive condition only) were observed during movement preparation. During movement cancellation, LIHI reduction in the continuing hand was greater than that in the stopping hand, and greater than LIHI reductions in both hands during execution of multicomponent responses. Our results indicate that foreknowledge attenuates stopping interference and provide evidence for a novel role of LIHI, mediated via prefrontal regions, in facilitating continuing action components.
Publisher: Elsevier BV
Date: 11-2021
DOI: 10.1016/J.BRS.2021.10.001
Abstract: Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive tool commonly used to drive neural plasticity in the young adult and aged brain. Recent data from mouse models have shown that even at subthreshold intensities (0.12 T), rTMS can drive neuronal and glial plasticity in the motor cortex. However, the physiological mechanisms underlying subthreshold rTMS induced plasticity and whether these are altered with normal ageing are unclear. To assess the effect of subthreshold rTMS, using the intermittent theta burst stimulation (iTBS) protocol on structural synaptic plasticity in the mouse motor cortex of young and aged mice. Longitudinal in vivo 2-photon microscopy was used to measure changes to the structural plasticity of pyramidal neuron dendritic spines in the motor cortex following a single train of subthreshold rTMS (in young adult and aged animals) or the same rTMS train administered on 4 consecutive days (in young adult animals only). Data were analysed with Bayesian hierarchical generalized linear regression models and interpreted with the aid of Bayes Factors (BF). We found strong evidence (BF > 10) that subthreshold rTMS altered the rate of dendritic spine losses and gains, dependent on the number of stimulation sessions and that a single session of subthreshold rTMS was effective in driving structural synaptic plasticity in both young adult and aged mice. These findings provide further evidence that rTMS drives synaptic plasticity in the brain and uncovers structural synaptic plasticity as a key mechanism of subthreshold rTMS induced plasticity.
Publisher: Springer Science and Business Media LLC
Date: 18-07-2022
DOI: 10.1186/S12883-022-02772-5
Abstract: The worldwide prevalence of dementia is rapidly rising. Alzheimer’s disease (AD), accounts for 70% of cases and has a 10–20-year preclinical period, when brain pathology covertly progresses before cognitive symptoms appear. The 2020 Lancet Commission estimates that 40% of dementia cases could be prevented by modifying lifestyle/medical risk factors. To optimise dementia prevention effectiveness, there is urgent need to identify in iduals with preclinical AD for targeted risk reduction. Current preclinical AD tests are too invasive, specialist or costly for population-level assessments. We have developed a new online test, TAS Test, that assesses a range of motor-cognitive functions and has capacity to be delivered at significant scale. TAS Test combines two innovations: using hand movement analysis to detect preclinical AD, and computer-human interface technologies to enable robust ‘self-testing’ data collection. The aims are to validate TAS Test to [1] identify preclinical AD, and [2] predict risk of cognitive decline and AD dementia. Aim 1 will be addressed through a cross-sectional study of 500 cognitively healthy older adults, who will complete TAS Test items comprising measures of motor control, processing speed, attention, visuospatial ability, memory and language. TAS Test measures will be compared to a blood-based AD biomarker, phosphorylated tau 181 (p-tau181). Aim 2 will be addressed through a 5-year prospective cohort study of 10,000 older adults. Participants will complete TAS Test annually and subtests of the Cambridge Neuropsychological Test Battery (CANTAB) biennially. 300 participants will undergo in-person clinical assessments. We will use machine learning of motor-cognitive performance on TAS Test to develop an algorithm that classifies preclinical AD risk (p-tau181-defined) and determine the precision to prospectively estimate 5-year risks of cognitive decline and AD. This study will establish the precision of TAS Test to identify preclinical AD and estimate risk of cognitive decline and AD. If accurate, TAS Test will provide a low-cost, accessible enrichment strategy to pre-screen in iduals for their likelihood of AD pathology prior to more expensive tests such as blood or imaging biomarkers. This would have wide applications in public health initiatives and clinical trials. ClinicalTrials.gov Identifier: NCT05194787 , 18 January 2022. Retrospectively registered.
Publisher: Springer Science and Business Media LLC
Date: 14-02-2007
DOI: 10.1007/S00221-007-0888-1
Abstract: An isometric torque-production task was used to investigate interference and retention in adaptation to multiple visuomotor environments. Subjects produced isometric flexion-extension and pronation-supination elbow torques to move a cursor to acquire targets as quickly as possible. Adaptation to a 30 degrees counter-clockwise (CCW) rotation (task A), was followed by a period of rest (control), trials with no rotation (task B0), or trials with a 60 degrees clockwise (CW) rotation (task B60). For all groups, retention of task A was assessed 5 h later. With initial training, all groups reduced the angular deviation of cursor paths early in the movements, indicating feedforward adaptation. For the control group, performance at commencement of the retest was significantly better than that at the beginning of the initial learning. For the B0 group, performance in the retest of task A was not dissimilar to that at the start of the initial learning, while for the B60 group retest performance in task A was markedly worse than initially observed. Our results indicate that close juxtaposition of two visuomotor environments precludes improved retest performance in the initial environment. Data for the B60 group, specifically larger angular errors upon retest compared with initial exposures, are consistent with the presence of anterograde interference. Furthermore, full interference occurred even when the visuomotor environment encountered in the second task was not rotated (B0). This latter novel result differs from those obtained for force field learning, where interference does not occur when task B does not impose perturbing forces, i.e., when B consists of a null field (Brashers-Krug et al., Nature 382:252-255, 1996). The results are consistent with recent proposals suggesting different interference mechanisms for visuomotor (kinematic) compared to force field (dynamic) adaptations, and have implications for the use of washout trials when studying interference between multiple visuomotor environments.
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.NEUROBIOLAGING.2021.09.014
Abstract: A wide body of literature suggests that transcranial direct current stimulation (tDCS) administered over the prefrontal cortex can improve executive function - including decision-making and inhibitory control - in healthy young adults. However, the effects of tDCS in older adults are largely unknown. Here, using a double-blind, sham-controlled approach, changes in a combined perceptual decision-making and inhibitory control task were assessed before and after the application of tDCS (1 mA, 20 minute) targeting the right inferior frontal gyrus (rIFG) or pre-supplementary motor area (preSMA) in 42 young (18-34 years) and 41 older (60-80 years) healthy adults. Compared to sham stimulation, anodal tDCS over the preSMA improved decision-making speed for both age groups. Furthermore, the inhibitory control performance of older and younger adults was improved by preSMA and rIFG stimulation, respectively. This study provides evidence that tDCS can improve both perceptual decision-making and inhibitory control in healthy older adults, with the causal role of the preSMA and rIFG regions in cognitive control appearing to vary as a function of healthy ageing.
Publisher: Elsevier BV
Date: 05-2014
DOI: 10.1016/J.BRS.2014.01.004
Abstract: The continued refinement of non-invasive brain stimulation (NBS) techniques is indicative of promising clinical and rehabilitative interventions that are able to modulate cortical excitability. Intermittent theta burst stimulation (iTBS) is one such technique that can increase cortical excitability, purportedly via LTP-like mechanisms. While iTBS may have the capacity to promote recovery after neurological injury, and to combat cognitive and motor decline, recent reports observed highly variable effects across in iduals, questioning the efficacy of iTBS as a clinical tool. The aim of this study was to examine intra-in idual reliability and inter-in idual variability in responses to iTBS. Thirty healthy participants completed two experimental sessions of the iTBS protocol 1-3 weeks apart. Motor evoked potentials in response to single pulse TMS were used to assess corticospinal excitability prior to, and up to 36 min following, iTBS. At the group level, iTBS evoked statistically significant increases in motor cortical excitability across both sessions (P < 0.001), with 22 out of 30 participants exhibiting increases in excitability in both sessions. A strong intraclass correlation demonstrated that both the direction, and magnitude of the plastic changes were reliable at the in idual level. Overall, our results suggest that iTBS is capable of inducing relatively robust and consistent effects within and between young in iduals. As such, the capacity for iTBS to be exploited in clinical and rehabilitative interventions should continue to be explored.
Publisher: Cold Spring Harbor Laboratory
Date: 05-05-2023
DOI: 10.1101/2023.05.03.539327
Abstract: The efficacy of transcranial alternating current stimulation (tACS) is thought to be brain state-dependent, such that tACS during task performance would be hypothesised to offer greater potential for inducing beneficial electrophysiological changes in the brain and associated behavioural improvement compared to tACS at rest. However, to date, no empirical study has directly tested this postulation. Here we compared the effects of tACS applied during a stop signal task (online) to the effects of the same tACS protocol applied prior to the task (offline) and a sham control stimulation. A total of 53 young, healthy adults (32 female 18-35 yrs) received dual-site beta tACS over the right inferior frontal gyrus (rIFG) and pre-supplementary motor area (preSMA), which are thought to play critical roles in action cancellation, with phase-synchronised stimulation for 15 min with the aim of increasing functional connectivity. EEG connectivity analysis revealed significantly increased task-related functional connectivity following online but not offline tACS. Correlation analyses suggested that an increase in functional connectivity in the beta band at rest following online tACS was associated with an improvement in response inhibition. Interestingly, despite the lack of changes in functional connectivity at the target frequency range following offline tACS, significant improvements in response inhibition were still observed, suggesting offline tACS may still be efficacious in inducing behavioural changes, likely via a post-stimulation early plasticity mechanism. Overall, the results indicate that online and offline dual-site beta tACS are beneficial in improving inhibitory control via distinct underlying mechanisms.
Publisher: Springer Science and Business Media LLC
Date: 16-11-2022
DOI: 10.3758/S13415-022-01047-3
Abstract: Response-selective stopping requires cancellation of only one component of a multicomponent action. While research has investigated how delays to the continuing action components (“stopping interference”) can be attenuated by way of contextual cues of the specific stopping demands (“foreknowledge”), little is known of the underlying neural mechanisms. Twenty-seven, healthy, young adults undertook a multicomponent stop-signal task. For two thirds of trials, participants responded to an imperative (go) stimulus (IS) with simultaneous button presses using their left and right index fingers. For the remaining one third of trials, the IS was followed by a stop-signal requiring cancellation of only the left, or right, response. To manipulate foreknowledge of stopping demands, a cue preceded the IS that informed participants which hand might be required to stop (proactive) or provided no such information (reactive). Transcranial magnetic stimulation (TMS) assessed corticospinal excitability (CSE) as well as short- and long-interval interhemispheric inhibition (SIHI, LIHI) between the primary motor cortices. Proactive cues reduced, but did not eliminate, stopping interference relative to the reactive condition. Relative to TMS measures at cue onset, decreases in CSE (both hands and both cue conditions) and LIHI (both hands, proactive condition only) were observed during movement preparation. During movement cancellation, LIHI reduction in the continuing hand was greater than that in the stopping hand and greater than LIHI reductions in both hands during execution of multicomponent responses. Our results indicate that foreknowledge attenuates stopping interference and provide evidence for a novel role of LIHI, mediated via prefrontal regions, in facilitating continuing action components.
Publisher: Cold Spring Harbor Laboratory
Date: 12-07-2023
DOI: 10.1101/2023.07.11.548624
Abstract: The ability to stop simple ongoing actions has been extensively studied using the stop signal task, but less is known about inhibition in more complex scenarios. Here we used a task requiring bimanual responses to go stimuli, but selective inhibition of only one of those responses following a stop signal. We assessed how proactive cues affect the nature of both the responding and stopping processes, and the well-documented “stopping delay” in the continuing action following successful stopping. In this task, estimates of the speed of inhibition based on a simple-stopping model are inappropriate, and have produced inconsistent findings about the effects of proactive control on motor inhibition. We instead used a multi-modal approach, based on improved methods of detecting and interpreting partial electromyographical (EMG) responses and the recently proposed SIS ( simultaneously inhibit and start ) model of selective stopping behaviour. Our results provide clear and converging evidence that proactive cues reduce the stopping delay effect by slowing bimanual responses and speeding unimanual responses, with a negligible effect on the speed of the stopping process.
Publisher: Public Library of Science (PLoS)
Date: 30-10-2015
Publisher: Informa UK Limited
Date: 04-06-2014
DOI: 10.1080/09602011.2014.922889
Abstract: Provision of a mirror image of a hand undertaking a motor task (i.e., mirror therapy) elicits behavioural improvements in the inactive hand. A greater understanding of the neural mechanisms underpinning this phenomenon is required to maximise its potential for rehabilitation across the lifespan, e.g., following hemiparesis or unilateral weakness. Young and older participants performed unilateral finger abductions with no visual feedback, with feedback of the active or passive hands, or with a mirror image of the active hand. Transcranial magnetic stimulation was used to assess feedback-related changes in two neurophysiological measures thought to be involved in inter-manual transfer of skill, namely corticospinal excitability (CSE) and intracortical inhibition (SICI) in the passive hemisphere. Task performance led to CSE increases, accompanied by decreases of SICI, in all visual feedback conditions relative to rest. However, the changes due to mirror feedback were not significantly different to those observed in the other (more standard) visual conditions. Accordingly, the unimanual motor action itself, rather than modifications in visual feedback, appears more instrumental in driving changes in CSE and SICI. Therefore, changes in CSE and SICI are unlikely to underpin the behavioural benefits of mirror therapy. We discuss implications for rehabilitation and directions of future research.
Publisher: Springer Science and Business Media LLC
Date: 17-04-2013
DOI: 10.1007/S00221-013-3511-7
Abstract: The present study investigated age-related changes in the attentional demands associated with interlimb coordination involving upper and lower limbs performed at three different movement frequencies. Younger and older adults performed rhythmical, 180° out-of-phase flexion-extension movements of the knee and elbow with either ipsilateral (right arm, right leg) or contralateral (right arm, left leg) limbs at 20, 60, and 100 % of each in idual's maximum movement frequency. A concurrent vocal reaction time task (dual task) was used to assess attentional load. There were two major findings: (1) The attentional cost associated with undertaking the required coordination patterns was greatest at the slowest movement frequency, and this additional attentional load was most pronounced for older adults (2) the manipulation of movement frequency had a distinct effect on the coordination performance: moving at the fastest frequency degraded the accuracy and stability of coordination, while moving at the slowest movement frequency led to increased temporal variability, particularly in older adults. Coordination performance at slowest movement frequency required the greatest cognitive demand in older adults relative to other movement frequencies, suggesting that going 'slow and steady' is not necessarily less attentionally demanding for older adults.
Publisher: Cold Spring Harbor Laboratory
Date: 23-10-2023
Publisher: American Physiological Society
Date: 09-2013
Abstract: A disruptive transcranial magnetic stimulation (TMS) approach was used to determine whether the increased frontal activation and reduced hemispheric laterality brain activation patterns observed in older adults during motor tasks play a functional role. Young and older adults abducted their left index finger as soon as possible after a visual imperative signal presented 500 ms after a warning signal. TMS was applied to the dorsal premotor (PMd) or primary motor (M1) cortex in the left or right hemisphere at seven times during response preparation and execution. Both groups exhibited faster reaction times in their left hand after stimulation of the left PMd (i.e., ipsilateral to the responding hand) relative to trials with no TMS, indicating a functional role of the left PMd in the regulation of impulse control. This result also suggests that the function of the left PMd appears to be unaffected by the healthy aging process. Right M1 TMS resulted in a response time delay in both groups. Only for older adults did left M1 stimulation delay responses, suggesting the involvement of ipsilateral motor pathways in the preparation of motor actions in older adults.
Publisher: American Physiological Society
Date: 03-2014
Abstract: Seminal work in animals indicates that learning a motor task results in long-term potentiation (LTP) in primary motor cortex (M1) and a subsequent occlusion of LTP induction (Rioult-Pedotti et al. J Neurophysiol 98: 3688–3695, 2007). Using various forms of noninvasive brain stimulation in conjunction with a motor learning paradigm, Cantarero et al. ( J Neurosci 33: 12862–12869, 2013) recently provided novel evidence to support the hypothesis that retention of motor skill is contingent upon this postlearning occlusion.
Publisher: Frontiers Media SA
Date: 05-06-2015
Publisher: Frontiers Media SA
Date: 02-06-2017
Publisher: Frontiers Media SA
Date: 06-06-2014
Publisher: Public Library of Science (PLoS)
Date: 19-12-2012
Publisher: Frontiers Media SA
Date: 30-06-2016
Publisher: Frontiers Media SA
Date: 12-2015
Publisher: SAGE Publications
Date: 24-03-2011
Abstract: Background/objective. Long-term changes in the motor cortex can be induced by practicing motor tasks with simultaneous application of peripheral nerve stimulation. This combination may augment motor rehabilitation after stroke but has been used primarily during contraction of the affected hand. The authors tested the effect of a right hand movement that electrically stimulated left hand contraction on right motor cortex excitability. Methods. Three tasks were used in 15 healthy subjects—a motor and stimulation task (MS task ), stimulation only task (S task ), and motor only task (M task ). The MS task consisted of isometric thumb abduction of the right hand that triggered paired electrical stimulation of the left abductor pollicis brevis (APB) and first dorsal interosseus (FDI) motor points. The S task was performed 1 week later and matched the stimulation received in the MS task . The M task was performed as a control. Transcranial magnetic stimulation applied to the right motor cortex assessed corticospinal excitability, short latency intracortical inhibition, and intracortical facilitation of the FDI and APB before, immediately after, and 30 minutes after task performance. Results. Corticospinal excitability increased in the FDI and APB following the MS task but not following the S task or M task . The increased excitability present 30 minutes after the MS task also correlated with excitability measures recorded 1 week later. Conclusion. A bilateral motor and electrical stimulation task can drive persistent adaptation within the corticospinal system. Hemiplegic subjects who have poor voluntary movement of the affected hand may be able to contract the unaffected hand to activate and train homologous movements.
Publisher: Elsevier BV
Date: 03-2021
Publisher: Center for Open Science
Date: 19-10-2023
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.NEUROIMAGE.2018.10.044
Abstract: Response inhibition, the ability to withhold a dominant and prepotent response following a change in circumstance or sensory stimuli, declines with advancing age. While non-invasive brain stimulation (NiBS) has shown promise in alleviating some cognitive and motor functions in healthy older in iduals, NiBS research focusing on response inhibition has mostly been conducted on younger adults. These extant studies have primarily focused on modulating the activity of distinct neural regions known to be critical for response inhibition, including the right inferior frontal gyrus (rIFG) and the pre-supplementary motor area (pre-SMA). However, given that changes in structural and functional connectivity have been associated with healthy aging, this review proposes that NiBS protocols aimed at modulating the functional connectivity between the rIFG and pre-SMA may be the most efficacious approach to investigate-and perhaps even alleviate-age-related deficits in inhibitory control.
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.NEUROBIOLAGING.2011.12.019
Abstract: The ability to coordinate upper and lower limbs--a prerequisite for many everyday activities--is known to decline with age. Here we report 2 experiments in which transcranial magnetic stimulation (TMS) was used to assess corticospinal excitatory and inhibitory processes in younger and older adults during cyclical hand-foot movements. In experiment 1, motor evoked potentials (MEP) and silent period (SP) durations were measured from the active right extensor carpi radialis (ECR) muscle while it executed rhythmic oscillations in conjunction with the right or left foot. Younger adults exhibited increased SP with ipsilateral limb combinations and decreased SP with contralateral limb combinations, relative to a baseline hand only condition. Strikingly, older adults exhibited a reduced SP when ipsilateral limbs moved in opposite directions. This effect was found to be most pronounced in those older adults who exhibited poor coordination performance, suggesting that the inability to regulate inhibitory processes may underlie age-related degradation of task performance. Experiment 2 examined motor evoked potentials and SP duration in the left extensor carpi radialis which maintained a tonic contraction while the coordination task was undertaken by the right arm and right or left foot. For younger adults, coordination of ipsilateral limbs was accompanied by increased inhibition in the ipsilateral motor cortex than during the coordination of contralateral limbs. No differences in SP between conditions were noted for the older adults. In summary, older adults' reduced ability to coordinate upper and lower limbs may be related to the capacity to regulate inhibitory function in both hemispheres. This study suggests for the first time a direct link between age-related differences in interlimb coordination and the control of corticospinal inhibitory processes.
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.NEUROIMAGE.2015.12.052
Abstract: Interactions between the cerebellum and primary motor cortex are crucial for the acquisition of new motor skills. Recent neuroimaging studies indicate that learning motor skills is associated with subsequent modulation of resting-state functional connectivity in the cerebellar and cerebral cortices. The neuronal processes underlying the motor-learning-induced plasticity are not well understood. Here, we investigate changes in functional connectivity in source-reconstructed electroencephalography (EEG) following the performance of a single session of a dynamic force task in twenty young adults. Source activity was reconstructed in 112 regions of interest (ROIs) and the functional connectivity between all ROIs was estimated using the imaginary part of coherence. Significant changes in resting-state connectivity were assessed using partial least squares (PLS). We found that subjects adapted their motor performance during the training session and showed improved accuracy but with slower movement times. A number of connections were significantly upregulated after motor training, principally involving connections within the cerebellum and between the cerebellum and motor cortex. Increased connectivity was confined to specific frequency ranges in the mu- and beta-bands. Post hoc analysis of the phase spectra of these cerebellar and cortico-cerebellar connections revealed an increased phase lag between motor cortical and cerebellar activity following motor practice. These findings show a reorganization of intrinsic cortico-cerebellar connectivity related to motor adaptation and demonstrate the potential of EEG connectivity analysis in source space to reveal the neuronal processes that underpin neural plasticity.
Publisher: Center for Open Science
Date: 17-01-2022
Abstract: We propose a new cognitive-modelling methodology that disentangles the non-linear interactions among psychological mechanisms underpinning behaviour in a complex task. We apply the approach to the domain of cognitive aging and show that it affords simultaneous measures of the major mechanisms proposed to explain age-related deficits: capacity limits, processing speed, inhibition, and executive function. The measures’ validities derive from the precisely specified roles of the model parameters and the model’s comprehensive, detailed, and accurate account of the behaviour of our healthy older and younger participants. Because it derives constraint from all aspects of participant’s behaviour, the analysis is powerful enough to provide clear results from a relatively small s le of participants who provide high quality data. When controlling for all other factors, we identify processing speed as the primary cause of age-related deficits. Executive control was better for older than younger participants when task demands were lower, but as demands increased this advantage reduced or disappeared, consistent with age-related capacity limitations. We conclude that such detailed cognitive models have the potential to be widely applied to provide an integrated, quantitative, and conceptually rich account of the many interacting psychological mechanisms that support behaviour in complex tasks.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.BRAINRES.2007.12.067
Abstract: We investigated the role of visual feedback in adapting to novel visuomotor environments. Participants produced isometric elbow torques to move a cursor towards visual targets. Following trials with no rotation, participants adapted to a 60 degrees rotation of the visual feedback before returning to the non-rotated condition. Participants received continuous visual feedback (CF) of cursor position during task execution or post-trial visual feedback (PF). With training, reductions of the angular deviations of the cursor path occurred to a similar extent and at a similar rate for CF and PF groups. However, upon re-exposure to the non-rotated environment only CF participants exhibited post-training aftereffects, manifested as increased angular deviation of the cursor path, with respect to the pre-rotation trials. These aftereffects occurred despite colour cues permitting identification of the change in environment. The results show that concurrent feedback permits automatic recalibration of the visuomotor mapping while post-trial feedback permits performance improvement via a cognitive strategy.
Publisher: Springer Science and Business Media LLC
Date: 05-03-2018
DOI: 10.1038/S41598-018-22385-8
Abstract: Repetitive transcranial magnetic stimulation (rTMS) is commonly used to modulate cortical plasticity in clinical and non-clinical populations. Clinically, rTMS is delivered to targeted regions of the cortex at high intensities ( T). We have previously shown that even at low intensities, rTMS induces structural and molecular plasticity in the rodent cortex. To determine whether low intensity rTMS (LI-rTMS) alters behavioural performance, daily intermittent theta burst LI-rTMS (120 mT) or sham was delivered as a priming or consolidating stimulus to mice completing 10 consecutive days of skilled reaching training. Relative to sham, priming LI-rTMS (before each training session), increased skill accuracy (~9%) but did not alter the rate of learning over time. In contrast, consolidating LI-rTMS (after each training session), resulted in a small increase in the rate of learning (an additional ~1.6% each day) but did not alter the daily skill accuracy. Changes in behaviour with LI-rTMS were not accompanied with long lasting changes in brain-derived neurotrophic factor (BDNF) expression or in the expression of plasticity markers at excitatory and inhibitory synapses for either priming or consolidation groups. These results suggest that LI-rTMS can alter specific aspects of skilled motor learning in a manner dependent on the timing of intervention.
Publisher: MIT Press - Journals
Date: 05-2012
DOI: 10.1162/JOCN_A_00201
Abstract: This study tested the postulation that change in the ability to modulate corticospinal excitability and inhibitory processes underlie age-related differences in response preparation and generation during tasks requiring either rapid execution of a motor action or actively withholding that same action. Younger (n = 13, mean age = 26.0 years) and older adults (n = 13, mean age = 65.5 years) performed an RT task in which a warning signal (WS) was followed by an imperative signal (IS) to which participants were required to respond with a rapid flexion of the right thumb (go condition) or withhold their response (no-go condition). We explored the neural correlates of response preparation, generation, and inhibition using single- and paired-pulse TMS, which was administered at various times between WS and IS (response preparation phase) and between IS and onset of response-related muscle activity in the right thumb (response generation phase). Both groups exhibited increases in motor-evoked potential litudes (relative to WS onset) during response generation however, this increase began earlier and was more pronounced for the younger adults in the go condition. Moreover, younger adults showed a general decrease in short-interval intracortical inhibition during response preparation in both the go and no-go conditions, which was not observed in older adults. Importantly, correlation analysis suggested that for older adults the task-related increases of corticospinal excitability and intracortical inhibition were associated with faster RT. We propose that the declined ability to functionally modulate corticospinal activity with advancing age may underlie response slowing in older adults.
Publisher: Wiley
Date: 27-06-2023
DOI: 10.1111/PSYP.14372
Abstract: Inhibiting ongoing responses when environmental demands change is a critical component of motor control. Experimentally, the stop signal task (SST) represents the gold standard response inhibition paradigm. However, an emerging body of evidence suggests that the SST conflates two dissociable sources of inhibition, namely an involuntarily pause associated with attentional capture and the (subsequent) voluntary cancellation of action. The extent to which these processes also occur in other response tasks is unknown. Younger n = 24 (20–35 years) and older n = 23 (60–85 years) adults completed tasks involving rapid unimanual or bimanual responses to visual stimuli. A subset of trials required cancellation of one component of an initial bimanual response (i.e., selective stop task stop left response, continue right response) or enacting an additional response (e.g., press left button as well as right button). Critically, both tasks involved some infrequent stimuli baring no behavioral imperative (i.e., they had to be ignored). EMG recordings of voluntary responses during stopping tasks revealed bimanual covert responses (muscle activation, which was suppressed before a button press ensued), consistent with a pause process, following both stop and ignore stimuli, before the required response was subsequently enacted. Critically , we also observed the behavioral consequences of a similar involuntary pause in trials where action cancellation was not part of the response set. Notably, the period over which movements were susceptible to response delays from additional stimuli was longer for older adults than younger adults. The findings demonstrate that an involuntary attentional component of inhibition significantly contributes to action cancellation processes.
No related organisations have been discovered for Mark Hinder.
Start Date: 03-2020
End Date: 12-2024
Amount: $366,310.00
Funder: Australian Research Council
View Funded ActivityStart Date: 01-2016
End Date: 12-2022
Amount: $660,751.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 12-2018
Amount: $340,739.00
Funder: Australian Research Council
View Funded ActivityStart Date: 03-2012
End Date: 01-2016
Amount: $375,000.00
Funder: Australian Research Council
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