ORCID Profile
0000-0002-4509-7518
Current Organisations
University of Southern Queensland
,
Edith Cowan University
,
University of Queensland
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Publisher: American Physiological Society
Date: 08-2023
Abstract: Our findings extend our understanding of neuromodulation induced by noninvasive electrical stimulation. We provide the first evidence showing acute online benefits of transcranial alternating current stimulation (tACS) triangle and tACS sine targeting the primary visual cortex (V1) on visual contrast detection in accordance with the resonance-like phenomenon. The “deterministic” tACS and “stochastic” high-frequency-transcranial random noise stimulation (tRNS) are equally effective in enhancing visual contrast detection.
Publisher: Public Library of Science (PLoS)
Date: 14-11-2013
Publisher: American Physiological Society
Date: 2020
DOI: 10.1152/JAPPLPHYSIOL.00595.2019
Abstract: Fatiguing exercise causes a reduction in motor drive to the muscle. Group III/IV muscle afferent firing is thought to contribute to this process however, the effect on corticospinal and intracortical networks is poorly understood. In two experiments, participants performed sustained maximal isometric finger abductions of the first dorsal interosseous (FDI) muscle, with postexercise blood flow occlusion (OCC) to maintain the firing of group III/IV afferents or without occlusion (control CON). Before and after exercise, single- and paired-pulse transcranial magnetic stimulation (TMS) tested motor evoked potentials (MEPs), intracortical facilitation [ICF (12 ms)], and short-interval intracortical inhibition [SICI 2 (2 ms), SICI 3 (3 ms)]. Ulnar nerve stimulation elicited maximal M waves (M MAX ). For experiment 1 ( n = 16 participants), TMS intensities were 70% and 120% of resting motor threshold (RMT) for the conditioning and MEP stimuli, respectively. For experiment 2 ( n = 16 participants), the MEP was maintained at 1 mV before and after exercise and the conditioning stimulus in idualized. In experiment 1, MEP/M MAX was reduced after exercise (~48%, P = 0.007) but was not different between conditions. No changes occurred in ICF or SICI. In experiment 2, MEP/M MAX increased (~27%, P = 0.027) and less inhibition (SICI 2 : ~21%, P = 0.021) occurred after exercise for both conditions, whereas ICF decreased for CON only (~28%, P = 0.006). MEPs and SICI 2 were modulated by fatiguing contractions but not by group III/IV afferent firing, whereas sustained afferent firing appeared to counteract postexercise reductions in ICF in FDI. The findings do not support the idea that actions of group III/IV afferents on motor cortical networks contribute to the reduction in voluntary activation observed in other studies. NEW & NOTEWORTHY This is the first study to investigate, in human hand muscles, the action of fatigue-related group III/IV muscle afferent firing on intracortical facilitation and inhibition. In fatigued and nonexercised hand muscles, intracortical inhibition is reduced after exercise but is not modulated differently by the firing of group III/IV afferents. However, facilitation is maintained for the fatigued muscle when group III/IV afferents fire, but these results are unlikely to explain the reduction in voluntary activation observed in other studies.
Publisher: Cold Spring Harbor Laboratory
Date: 31-07-2023
DOI: 10.1101/2023.07.30.23293287
Abstract: Multiple sclerosis (MS) is a chronic progressive neurological disease. There is le evidence that exercise can be beneficial. The advancement of modern technology led to improvements in the way therapy can be offered and can make it more motivating, thereby increasing adherence. The primary objective of this two site single blinded randomized control trial (RCT) is to explore the feasibility of conducting a multicentre definite RCT trial with a neuroanimation intervention of high-dose practice in people with mild-to-moderate MS. The secondary objective is to collect data on the variability of outcome measures to inform s le size calculations for a RCT. The tertiary outcome is to assess if this intervention changes exercise behaviour. This study is in preparation for a future definitive randomised control trial (RCT) where the efficacy compared to a dose matched control therapy will be assessed. The setting for this study is a research laboratory at Edith Cowan University (ECU) and a neurological service provider, Multiple Sclerosis Society of Western Australia (MSWA). This feasibility study will recruit people with MS who have mild to moderate disability. Subjects will participate in 24 session, 2 times a week, of 60 minutes time-on-task intense arm training, using an exergaming system. Participants will undergo a follow up within 3 days and at 6 months after the final study visit. This study was approved by the local Ethics Committee of Edith Cowan University. Subjects will be included after signing informed consent. Study outcomes will be disseminated through presentations at scientific conferences and through peer-reviewed journals. ACTRN12622000281796 The study intervention is a newly developed exercise intervention protocol designed to be engaging and motivating Next to investigating primary efficacy in order to determine s le size for a larger trial, the study also uses implementation science to assess future obstacles in a follow up randomized control trial The feasibility of conducting a larger trial will be based on standardised criteria regarding process, resource, and management metrics This study without a control group demonstrates feasibility rather than efficacy
Publisher: SAGE Publications
Date: 2023
DOI: 10.1177/16094069231180162
Abstract: There is a need to identify why multiple sclerosis exercise research is not translating into real-world participation. To lay the foundations of strong clinical research, considering the translational element of implementation science at the feasibility phase of a trial is vital. Document analysis was used to examine document sources on exercise activity interventions designed for people living with multiple sclerosis. Document sources focused on multiple sclerosis research that incorporated exercise prescription elements and behaviour change and were feasibility studies incorporating aspects of implementation science. Implementation science should come much earlier than the efficacy or effectiveness research pipeline. An alternate view is outlined where feasibility and implementation science should meet based on case ex les that have not yet shown strong efficacy or effectiveness. Findings from our key themes indicate a need for a cyclical iterative approach to the translational process. Multiple aspects of feasibility and how it can be assessed using an implementation science lens to support more successful interventions are provided. The determination of feasibility in behaviour change should involve implementation science as feasibility is drawn on for theory development, optimising the intervention design and quality of implementation strategies, and identifying those delivering the intervention before conducting efficacy and effectiveness research. Document analysis methodology is underused in qualitative research and was appropriate to use as it was a very resource, time-efficient and an unobtrusive process that could track change and development to explore the integration of implementation science at the feasibility phase, with the findings indicating the earlier implementation science is introduced into multiple sclerosis exercise interventions the better.
Publisher: Springer Science and Business Media LLC
Date: 11-03-2019
DOI: 10.1038/S41598-019-40335-W
Abstract: Random noise can enhance the detectability of weak signals in nonlinear systems, a phenomenon known as stochastic resonance (SR). This concept is not only applicable to single threshold systems but can also be applied to dynamical systems with multiple attractor states, such as observed during the phenomenon of binocular rivalry. Binocular rivalry can be characterized by marginally stable attractor states between which the brain switches in a spontaneous, stochastic manner. Here we used a computational model to predict the effect of noise on perceptual dominance durations. Subsequently we compared the model prediction to a series of experiments where we measured binocular rivalry dynamics when noise (zero-mean Gaussian random noise) was added either to the visual stimulus (Exp. 1) or directly to the visual cortex (Exp. 2) by applying transcranial Random Noise Stimulation (tRNS 1 mA, 100–640 Hz zero -mean Gaussian random noise). We found that adding noise significantly reduced the mixed percept duration (Exp. 1 and Exp. 2). Our results are the first to demonstrate that both central and peripheral noise can influence state-switching dynamics of binocular rivalry under specific conditions (e.g. low visual contrast stimuli), in line with a SR-mechanism.
Publisher: Society for Neuroscience
Date: 17-12-2021
DOI: 10.1523/ENEURO.0248-21.2021
Abstract: Noise introduced in the human nervous system from cellular to systems levels can have a major impact on signal processing. Using transcranial stimulation, electrical noise can be added to cortical circuits to modulate neuronal activity and enhance function in the healthy brain and in neurologic patients. Transcranial random noise stimulation (tRNS) is a promising technique that is less well understood than other non-invasive neuromodulatory methods. The aim of the present scoping review is to collate published evidence on the effects of electrical noise at the cellular, systems, and behavioral levels, and discuss how this emerging method might be harnessed to augment perceptual and motor functioning of the human nervous system. Online databases were used to identify papers published in 2008–2021 using tRNS in humans, from which we identified 70 publications focusing on sensory and motor function. Additionally, we interpret the existing evidence by referring to articles investigating the effects of noise stimulation in animal and subcellular models. We review physiological and behavioral findings of tRNS-induced offline after-effects and acute online benefits which manifest immediately when tRNS is applied to sensory or motor cortices. We link these results to evidence showing that activity of voltage-gated sodium ion channels might be an important cellular substrate for mediating these tRNS effects. We argue that tRNS might make neural signal transmission and processing within neuronal populations more efficient, which could contribute to both (1) offline after-effects in the form of a prolonged increase in cortical excitability and (2) acute online noise benefits when computations rely on weak inputs.
Publisher: Cold Spring Harbor Laboratory
Date: 30-11-2017
DOI: 10.1101/227140
Abstract: Random noise can enhance the detectability of weak signals in nonlinear threshold systems, a phenomenon known as stochastic resonance (SR). This concept is not only applicable to single threshold systems but can also be applied to dynamical systems with multiple attractor states, such as observed during the phenomenon of binocular rivalry. Binocular rivalry can be characterized by marginally stable attractor states between which the brain switches in a spontaneous, stochastic manner. The switches are thought to be driven by a combination of neuronal adaptation and noise. Here we used a computational model to predict the effect of noise on perceptual dominance durations when either low-contrast or high-contrast stimuli are presented. Subsequently we compared the model prediction to a series of three experiments where we measured binocular rivalry dynamics when noise (zero-mean Gaussian white noise) was added either to the visual stimulus (Exp. 1) or directly to the visual cortex (Exp. 2 and Exp. 3) by applying transcranial Random Noise Stimulation (tRNS 1mA, 100-640 Hz zero mean Gaussian white noise). We found that adding noise significantly reduced the mixed percept duration (Exp. 1 and Exp. 2). This effect was only present for low-contrast but not for high-contrast visual stimuli which is in line with the model predictions. Our results demonstrate that both central and peripheral noise can influence state-switching dynamics of binocular rivalry under specific conditions (e.g. low visual contrast stimuli), in line with a SR-mechanism.
Publisher: Springer International Publishing
Date: 2020
Publisher: Elsevier BV
Date: 04-2023
Publisher: Cold Spring Harbor Laboratory
Date: 13-08-2017
DOI: 10.1101/175455
Abstract: Perceptual decision-making relies on the gradual accumulation of noisy sensory evidence until a specified boundary is reached and an appropriate response is made. It might be assumed that adding noise to a stimulus, or to the neural systems involved in its processing, would interfere with the decision process. But it has been suggested that adding an optimal amount of noise can, under appropriate conditions, enhance the quality of subthreshold signals in nonlinear systems, a phenomenon known as stochastic resonance . Here we asked whether perceptual decisions obey these stochastic resonance principles by adding noise directly to the visual cortex using transcranial random noise stimulation (tRNS) while participants judged the direction of motion in foveally presented random-dot motion arrays. Consistent with the stochastic resonance account, we found that adding tRNS bilaterally to visual cortex enhanced decision-making when stimuli were just below, but not well below or above, perceptual threshold. We modelled the data under a drift diffusion framework to isolate the specific components of the multi-stage decision process that were influenced by the addition of neural noise. This modelling showed that tRNS increased drift rate, which indexes the rate of evidence accumulation, but had no effect on bound separation or non-decision time. These results were specific to bilateral stimulation of visual cortex control experiments involving unilateral stimulation of left and right visual areas showed no influence of random noise stimulation. Our study is the first to provide causal evidence that perceptual decision-making is susceptible to a stochastic resonance effect induced by tRNS, and that this effect arises from selective enhancement of the rate of evidence accumulation for sub-threshold sensory events.
Publisher: Cold Spring Harbor Laboratory
Date: 04-08-2023
DOI: 10.1101/2023.07.31.23293284
Abstract: Stroke is a leading cause of adult disability and high-dose interventions may help reduce it. However, current practice does not allow for this. This study tests the feasibility of a high-dose upper limb therapy in chronic stroke survivors using a neuroanimation therapy (NAT). Four chronic stroke survivors underwent 20 NAT sessions, 3 or 5 times a week for 90 minutes time-on-task. Feasibility was assessed with compliance to number of sessions and total time-on-task. Secondary outcomes included Fugle-Meyer Upper Extremity motor score (FM-UE), Action Research Arm Test (ARAT), grip strength, movement kinematics and cognition assessed using robotic technology. All participants attended the 20 prescribed sessions on the 3-day per week schedule. Two completed 90 minutes time-on-task in all sessions. Two showed clinical improvements in their FM-UE and ARAT. Movement kinematic analysis demonstrated improvements in motor control and cognition, however these changes did not seem to last when re-tested 1 month after the last training session. 20 sessions of NAT is feasible in the chronic phase of stroke recovery with a 3-day per week schedule. Clinical improvements in arm function were observed in this high-dose upper limb NAT therapy, in one mild and one moderately affected stroke survivor.
Publisher: Elsevier BV
Date: 07-2022
DOI: 10.1016/J.NEUBIOREV.2022.104702
Abstract: Van der Groen, O., Potok, W., Wenderoth, N., Edwards, G., Mattingley, J.B. and Edwards, D. Using noise for the better: The effects of transcranial random noise stimulation on the brain and behavior. NEUROSCI BIOBEHAV REV X (X) XXX-XXX 2021.- Transcranial random noise stimulation (tRNS) is a non-invasive electrical brain stimulation method that is increasingly employed in studies of human brain function and behavior, in health and disease. tRNS is effective in modulating perception acutely and can improve learning. By contrast, its effectiveness for modulating higher cognitive processes is variable. Prolonged stimulation with tRNS, either as one longer application, or multiple shorter applications, may engage plasticity mechanisms that can result in long-term benefits. Here we provide an overview of the current understanding of the effects of tRNS on the brain and behavior and provide some specific recommendations for future research.
Publisher: Public Library of Science (PLoS)
Date: 18-07-2018
Publisher: Society for Neuroscience
Date: 11-05-2016
DOI: 10.1523/JNEUROSCI.4519-15.2016
Abstract: Random noise enhances the detectability of weak signals in nonlinear systems, a phenomenon known as stochastic resonance (SR). Though counterintuitive at first, SR has been demonstrated in a variety of naturally occurring processes, including human perception, where it has been shown that adding noise directly to weak visual, tactile, or auditory stimuli enhances detection performance. These results indicate that random noise can push subthreshold receptor potentials across the transfer threshold, causing action potentials in an otherwise silent afference. Despite the wealth of evidence demonstrating SR for noise added to a stimulus, relatively few studies have explored whether or not noise added directly to cortical networks enhances sensory detection. Here we administered transcranial random noise stimulation (tRNS 100–640 Hz zero-mean Gaussian white noise) to the occipital region of human participants. For increasing tRNS intensities (ranging from 0 to 1.5 mA), the detection accuracy of a visual stimuli changed according to an inverted-U-shaped function, typical of the SR phenomenon. When the optimal level of noise was added to visual cortex, detection performance improved significantly relative to a zero noise condition (9.7 ± 4.6%) and to a similar extent as optimal noise added to the visual stimuli (11.2 ± 4.7%). Our results demonstrate that adding noise to cortical networks can improve human behavior and that tRNS is an appropriate tool to exploit this mechanism. SIGNIFICANCE STATEMENT Our findings suggest that neural processing at the network level exhibits nonlinear system properties that are sensitive to the stochastic resonance phenomenon and highlight the usefulness of tRNS as a tool to modulate human behavior. Since tRNS can be applied to all cortical areas, exploiting the SR phenomenon is not restricted to the perceptual domain, but can be used for other functions that depend on nonlinear neural dynamics (e.g., decision making, task switching, response inhibition, and many other processes). This will open new avenues for using tRNS to investigate brain function and enhance the behavior of healthy in iduals or patients.
Publisher: Cold Spring Harbor Laboratory
Date: 09-10-2020
DOI: 10.1101/2020.10.07.329813
Abstract: Transcranial random noise stimulation (tRNS) over cortical areas has been shown to acutely improve performance in sensory detection tasks. One explanation for this behavioural effect is stochastic resonance, a mechanism that explains how signal processing in non-linear systems can benefit from added noise. While acute noise benefits of electrical random noise stimulation have been demonstrated at the behavioural level as well as in in vitro preparations of neural tissue, it is currently largely unknown whether similar effects can be shown at the neural population level using neurophysiological readouts of human cortex. Here we hypothesized that acute tRNS will increase the responsiveness of primary motor cortex (M1) when probed with transcranial magnetic stimulation. Neural responsiveness was operationalized via the well-known concept of the resting motor threshold (RMT). We showed that tRNS acutely decreases RMT. This effect was small, but it was consistently replicated across four experiments including different cohorts (total N=81, 46 females, 35 males), two tRNS electrode montages, and different control conditions. Our experiments provide critical neurophysiological evidence that tRNS can acutely generate noise benefits by enhancing the neural population response of human M1. A hallmark feature of stochastic resonance is that signal processing can benefit from added noise. This has mainly been demonstrated at the single-cell level in vitro where the neural response to weak input signals can be enhanced by simultaneously applying random noise. Our finding that tRNS acutely increases the excitability of corticomotor circuits extends the principle of noise benefits to the neural population level in human cortex. Our finding is in line with the notion that tRNS might affect cortical processing via the stochastic resonance phenomenon. It suggests that enhancing the response of cortical populations to an external stimulus might be one neurophysiological mechanism mediating performance improvements when tRNS is applied to sensory cortex during perception tasks.
Publisher: Society for Neuroscience
Date: 18-03-2021
DOI: 10.1523/JNEUROSCI.2961-20.2021
Abstract: Transcranial random noise stimulation (tRNS) over cortical areas has been shown to acutely improve performance in sensory detection tasks. One explanation for this behavioral effect is stochastic resonance (SR), a mechanism that explains how signal processing in nonlinear systems can benefit from added noise. While acute noise benefits of electrical RNS have been demonstrated at the behavioral level as well as in in vitro preparations of neural tissue, it is currently largely unknown whether similar effects can be shown at the neural population level using neurophysiological readouts of human cortex. Here, we hypothesized that acute tRNS will increase the responsiveness of primary motor cortex (M1) when probed with transcranial magnetic stimulation (TMS). Neural responsiveness was operationalized via the well-known concept of the resting motor threshold (RMT). We showed that tRNS acutely decreases RMT. This effect was small, but it was consistently replicated across four experiments including different cohorts (total N = 81, 46 females, 35 males), two tRNS electrode montages, and different control conditions. Our experiments provide critical neurophysiological evidence that tRNS can acutely generate noise benefits by enhancing the neural population response of human M1. SIGNIFICANCE STATEMENT A hallmark feature of stochastic resonance (SR) is that signal processing can benefit from added noise. This has mainly been demonstrated at the single-cell level in vitro where the neural response to weak input signals can be enhanced by simultaneously applying random noise. Our finding that transcranial random noise stimulation (tRNS) acutely increases the excitability of corticomotor circuits extends the principle of noise benefits to the neural population level in human cortex. Our finding is in line with the notion that tRNS might affect cortical processing via the SR phenomenon. It suggests that enhancing the response of cortical populations to an external stimulus might be one neurophysiological mechanism mediating performance improvements when tRNS is applied to sensory cortex during perception tasks.
Publisher: IOP Publishing
Date: 25-08-2015
Publisher: Cold Spring Harbor Laboratory
Date: 03-11-2022
DOI: 10.1101/2022.11.03.515008
Abstract: Stochastic Resonance (SR) describes a phenomenon where an additive noise (stochastic carrier-wave) enhances the signal transmission in a nonlinear system. In the nervous system, nonlinear properties are present from the level of single ion channels all the way to perception and appear to support the emergence of SR. For ex le, SR has been repeatedly demonstrated for visual detection tasks, also by adding noise directly to cortical areas via transcranial random noise stimulation (tRNS). We mathematically show that high-frequency, non-stochastic, periodic signals can yield resonance-like effects with linear transfer and infinite signal-to-noise ratio at the output. Here we tested this prediction empirically and investigated whether non-random, high-frequency, transcranial alternating current stimulation (hf-tACS) applied to visual cortex could induce resonance-like effects and enhance performance on a visual detection task. We demonstrated in 28 participants that applying 80 Hz triangular-waves or sine-waves with hf-tACS reduced visual contrast detection threshold for optimal brain stimulation intensities. The influence of hf-tACS on contrast sensitivity was equally effective to tRNS-induced modulation, demonstrating that both hf-tACS and tRNS can reduce contrast detection thresholds. Our findings suggest that a resonance-like mechanism can also emerge when non-stochastic electrical waveforms are applied via hf-tACS. Our findings extend our understanding of neuromodulation induced by noninvasive electrical stimulation. We provide first evidence showing acute online benefits of hf-tACS triangle and hf-tACS sine targeting the primary visual cortex (V1) on visual contrast detection in accordance with the resonance-like phenomenon. The ‘non-stochastic’ hf-tACS and ‘stochastic’ hf-tRNS are equally effective in enhancing visual contrast detection.
Start Date: 2014
End Date: 2017
Funder: Swiss National Science Foundation
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