Winston D Byblow

Winston D Byblow
University of Auckland · Department of Exercise Sciences

PhD (Simon Fraser)

About

253
Publications
40,163
Reads
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11,197
Citations
Additional affiliations
January 2008 - present
University of Auckland
Position
  • Professor of Neuroscience
January 1997 - present
University of Auckland
Position
  • Professor (Full)
September 1988 - April 1994
Simon Fraser University
Position
  • PhD Student

Publications

Publications (253)
Article
Full-text available
Background Persistent sensorimotor impairments after stroke can negatively impact quality of life. The hippocampus is vulnerable to poststroke secondary degeneration and is involved in sensorimotor behavior but has not been widely studied within the context of poststroke upper‐limb sensorimotor impairment. We investigated associations between non‐l...
Preprint
Full-text available
Sensorimotor performance after stroke is strongly related to focal injury measures such as corticospinal tract lesion load. However, the role of global brain health is less clear. Here, we examined the impact of brain age, a measure of neurobiological aging derived from whole brain structural neuroimaging, on sensorimotor outcomes. We hypothesized...
Article
Response inhibition is an essential aspect of cognitive control that is necessary for terminating inappropriate preplanned or ongoing responses. Response-selective stopping represents a complex form of response inhibition where only a subcomponent of a multicomponent action must be terminated. In this context, a substantial response delay emerges o...
Article
Full-text available
Background Motor outcomes after stroke can be predicted using structural and functional biomarkers of the descending corticomotor pathway, typically measured using magnetic resonance imaging and transcranial magnetic stimulation, respectively. However, the precise structural determinants of intact corticomotor function are unknown. Identifying stru...
Article
Response inhibition is essential for goal-directed behavior within dynamic environments. Selective stopping is a complex form of response inhibition where only part of a multi-effector response must be cancelled. A substantial response delay emerges on unstopped effectors when a cued effector is successfully stopped. This stopping-interference effe...
Preprint
Full-text available
Objective The role of ipsilateral descending motor pathways in voluntary movement of humans is still a matter of debate. Few studies have examined the task dependent modulation of ipsilateral motor evoked potentials (iMEPs). Here, we determined the location of upper limb biceps brachii (BB) representation within the ipsilateral primary motor cortex...
Preprint
Full-text available
Persistent sensorimotor impairments after stroke can negatively impact quality of life. The hippocampus is involved in sensorimotor behavior but has not been widely studied within the context of post-stroke upper limb sensorimotor impairment. The hippocampus is vulnerable to secondary degeneration after stroke, and damage to this region could furth...
Article
Full-text available
Up to two-thirds of stroke survivors experience persistent sensorimotor impairments. Recovery relies on the integrity of spared brain areas to compensate for damaged tissue. Deep grey matter structures play a critical role in the control and regulation of sensorimotor circuits. The goal of this work is to identify associations between volumes of sp...
Article
Background and Purpose The ARAT (Action Research Arm Test) has been used to classify upper limb motor outcome after stroke in 1 of 3, 4, or 5 categories. The coronavirus disease 2019 (COVID-19) pandemic has encouraged the development of assessments that can be performed quickly and remotely. The aim of this study was to derive and internally valida...
Article
Full-text available
Introduction Up to 40% of Parkinson’s disease patients taking dopamine agonist medication develop impulse control behaviors which can have severe negative consequences. The current study aimed to utilize dopamine genetics to identify patients most at risk of developing these behaviors. Methods Demographic, clinical, and genetic data were obtained...
Preprint
The proportional recovery rule (PRR) posits that most stroke survivors can expect to reverse a fixed proportion of motor impairment. As a statistical model, the PRR explicitly relates change scores to baseline values -- an approach that has the potential to introduce artifacts and flawed conclusions. We describe approaches that can assess associati...
Article
Full-text available
Bimanual coordination is essential for the performance of many everyday tasks. There are several types of bimanually coordinated movements, classified according to whether the arms are acting to achieve a single goal (cooperative) or separate goals (independent), and whether the arms are moving symmetrically or asymmetrically. Symmetric bimanual mo...
Article
Full-text available
Precise control of upper limb movements in response to external stimuli is vital to effectively interact with the environment. Accurate execution of bimanual movement is known to rely on finely orchestrated interhemispheric communication between the primary motor cortices (M1s). However, relatively little is known about the role of interhemispheric...
Preprint
Full-text available
Objective To identify associations between atrophy of spared subcortical nuclei and sensorimotor behavior at different timepoints after stroke. Methods We pooled high-resolution T1-weighted MRI brain scans and behavioral data in 828 individuals with unilateral stroke from 28 cohorts worldwide. Cross-sectional analyses using linear mixed-effects mo...
Article
Full-text available
Modulation of GABA-mediated inhibition in primary motor cortex (M1) is important for the induction of training-induced plasticity. The downregulation of inhibition during acquisition may promote cortical reorganization, whereas an upregulation once performance has plateaued may promote consolidation of the newly acquired skill. GABA-related inhibit...
Article
Full-text available
The goal of the Enhancing Neuroimaging Genetics through Meta‐Analysis (ENIGMA) Stroke Recovery working group is to understand brain and behavior relationships using well‐powered meta‐ and mega‐analytic approaches. ENIGMA Stroke Recovery has data from over 2,100 stroke patients collected across 39 research studies and 10 countries around the world,...
Article
Stroke is a leading cause of death and disability worldwide with many people left with impaired motor function. Evidence from experimental animal models of stroke indicates that reducing motor cortex inhibition may facilitate neural plasticity and motor recovery. This study compared primary motor cortex (M1) inhibition measures over the first 12 we...
Article
Full-text available
Motor imagery (MI) is the mental simulation of an action without any apparent muscular contraction. By means of transcranial magnetic stimulation, few studies revealed a decrease of short-interval intracortical inhibition (SICI) within the primary motor cortex. However, this decrease is ambiguous, as one would expect greater inhibition during MI to...
Article
Stroke remains a leading cause of adult disability and the demand for stroke rehabilitation services is growing. Substantial advances are yet to be made in stroke rehabilitation practice to meet this demand and improve patient outcomes relative to current care. Several large intervention trials targeting motor recovery report that participants' mot...
Article
Objective: Motor learning is relevant in chronic stroke for acquiring compensatory strategies to motor control deficits. However, the neurophysiological mechanisms underlying motor skill acquisition with the paretic upper limb have received little systematic investigation. The aim of this study was to assess the modulation of corticomotor excitabi...
Preprint
Full-text available
The goal of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Stroke Recovery working group is to understand brain and behavior relationships using well-powered meta- and mega-analytic approaches. ENIGMA Stroke Recovery has data from over 1,800 stroke patients collected across 32 research sites and 10 countries around the world, co...
Article
Full-text available
To better understand how arm weight support (WS) can be used to alleviate upper limb impairment after stroke, we investigated the effects of WS on muscle activity, muscle synergy expression, and corticomotor excitability (CME) in 13 chronic stroke patients and 6 age-similar healthy controls. For patients, lesion location and corticospinal tract int...
Preprint
Full-text available
Motor imagery (MI) is the mental simulation of an action without any apparent muscular contraction. By means of transcranial magnetic stimulation, few studies revealed a decrease of short-interval intracortical inhibition (SICI) within the primary motor cortex. However, this decrease is ambiguous, as one would expect greater inhibition during MI to...
Preprint
Full-text available
To elucidate the underlying physiological mechanism of muscle synergies, we investigated the functional corticomuscular and intermuscular binding during an isometric upper limb task in 14 healthy participants. Cortical activity was recorded using 32-channel encephalography (EEG) and muscle activity using 16-channel electromyography (EMG). Using non...
Article
Full-text available
The ability to acquire and retain novel motor skills is preserved with advancing age. However, the neurophysiological mechanisms underlying skill acquisition in older adults have received little systematic investigation. The aim of the present study was to assess the modulation of primary motor cortex excitability and inhibition after skill acquisi...
Article
Response inhibition reflects the process of terminating inappropriate pre-planned or ongoing movements. When one hand is cued to stop after preparing a bimanual response (Partial trial) there is a substantial delay on the responding side. This delay is termed the interference effect and identifies a constraint that limits selective response inhibit...
Article
Background. The PREP2 algorithm combines clinical and neurophysiological measures to predict upper-limb (UL) motor outcomes 3 months poststroke, using 4 prediction categories based on Action Research Arm Test (ARAT) scores. The algorithm was accurate at 3 months for 75% of participants in a previous validation study. Objective. This study aimed to...
Preprint
Full-text available
To better understand how arm weight support (WS) can be used to alleviate upper limb impairment after stroke, we investigated the effects of WS on muscle activity, muscle synergy expression, and corticomotor excitability (CME) in 13 chronic stroke patients and 6 age-similar healthy controls. For patients, lesion location and corticospinal tract int...
Article
There is high inter-individual variability in recovery after stroke, which reduces statistical power in rehabilitation trials. This could be addressed by using biomarkers for patient selection. Corticospinal tract function assessed with transcranial magnetic stimulation (TMS) is a candidate biomarker for trials aiming to improve upper-limb motor re...
Article
Background: After stroke, there may be abnormalities in gamma-aminobutyric acid (GABA)-mediated inhibitory function within primary motor cortex (M1), which may have implications for residual motor impairment and the potential for functional improvements at the chronic stage. The present study examined primary motor cortex (M1) inhibition in patient...
Article
Background: Stroke is a leading cause of adult disability owing largely to motor impairment and loss of function. After stroke, there may be abnormalities in γ-aminobutyric acid (GABA)-mediated inhibitory function within primary motor cortex (M1), which may have implications for residual motor impairment and the potential for functional improvemen...
Article
Background: Non-invasive neuromodulation may provide treatment strategies for neurological deficits affecting movement, such as stroke. For example, weak electrical stimulation applied to the hand by wearing a "mesh glove" (MGS) can transiently increase primary motor cortex (M1) excitability. Conversely, transcranial direct current stimulation wit...
Preprint
Full-text available
Background and Purpose: Inter-subject variability complicates trials of novel stroke rehabilitation therapies, particularly in the sub-acute phase after stroke. We tested whether selecting patients using motor evoked potential (MEP) status, a physiological biomarker of motor system function, could improve trial efficiency. Methods: A retrospective...
Article
Interhemispheric inhibition between bilateral motor cortices is important for the performance of unimanual activities and may be compromised with advancing age. Conventionally, interhemispheric inhibition is assessed using paired‐pulse transcranial magnetic stimulation with constant conditioning and test stimulation parameters. Adaptive threshold h...
Article
Background: There is growing interest in using biomarkers to predict motor recovery and outcomes after stroke. The PREP2 algorithm combines clinical assessment with biomarkers in an algorithm, to predict upper limb functional outcomes for individual patients. To date, PREP2 is the first algorithm to be tested in clinical practice, and other biomar...
Article
Background: In human primary motor cortex (M1), the paired-pulse transcranial magnetic stimulation (TMS) paradigm of short-interval intracortical inhibition (SICI) can be expressed conventionally as a percent change in the relative amplitude of a conditioned motor evoked potential to non-conditioned; or adaptive threshold-hunting a target motor ev...
Article
Full-text available
Primary motor cortex excitability can be modulated by anodal and cathodal transcranial direct current stimulation (tDCS). These neuromodulatory effects may, in part, be dependent on modulation within gamma-aminobutyric acid (GABA)-mediated inhibitory networks. GABAergic function can be quantified non-invasively using adaptive threshold hunting pair...
Article
Full-text available
The development of fatigue elicits multiple adaptations from the neuromuscular system. Muscle synergies are common patterns of neuromuscular activation that have been proposed as the building blocks of human movement. We wanted to identify possible adaptations of muscle synergies to the development of fatigue in the upper limb. Recent studies have...
Article
Associations between subcortical gray matter volume and motor performance post-stroke are unclear, partly because many stroke MRI studies are underpowered. Potential influences of the severity of motor impairment, lesion laterality, and time since stroke on these associations is also unknown. Here, we addressed these questions using a large dataset...
Preprint
Full-text available
The development of fatigue elicits multiple adaptations from the neuromuscular system. Muscle synergies are common patterns of neuromuscular activation that have been proposed as the building blocks of human movement. We wanted to identify possible adaptations of muscle synergies to the development of fatigue in the upper limb. Recent studies have...
Chapter
Transcranial magnetic stimulation (TMS) is a safe, non-invasive technique for studying the human motor system. It can be used to evaluate primary motor cortex (M1) function after stroke, by stimulating the ipsilesional M1 and recording motor-evoked potentials (MEPs) from the paretic limbs. In this chapter, we first outline the measures of M1, intra...
Article
Full-text available
Objective Recovery of motor function is important for regaining independence after stroke, but difficult to predict for individual patients. Our aim was to develop an efficient, accurate, and accessible algorithm for use in clinical settings. Clinical, neurophysiological, and neuroimaging biomarkers of corticospinal integrity obtained within days o...
Article
Full-text available
Objective: Chronic stroke patients with moderate-severe motor impairment may have an increased reliance on contralesional vs ipsilesional motor areas to control the paretic arm. We hypothesised that increasing contralesional excitability with anodal transcranial direct current stimulation (a-tDCS) would benefit motor performance in patients with m...
Article
Objective: Cervical propriospinal premotoneurons (PN) relay descending motor commands and integrate peripheral afferent feedback. Effects of anodal transcranial direct current stimulation (a-tDCS) on propriospinal excitability in the upper limbs are unknown. Methods: Healthy right-handed adults received a-tDCS or sham tDCS over primary motor cor...
Article
The effects of healthy ageing on gamma-aminobutyric acid (GABA) within primary motor cortex (M1) remain poorly understood. Studies have reported contrasting results, potentially due to limitations with the common assessment technique. The aim of the present study was to investigate the effect of healthy ageing on M1 GABA concentration and neurotran...
Article
Background and purpose: In people with preserved corticospinal tract (CST) function after stroke, upper limb impairment resolves by ?70% within 3 months. This is known as the proportional recovery rule. Patients without CST function do not fit this rule and have worse upper limb outcomes. This study investigated resolution of motor impairment in t...
Article
Full-text available
Background and purpose: Several clinical measures and biomarkers are associated with motor recovery after stroke, but none are used to guide rehabilitation for individual patients. The objective of this study was to evaluate the implementation of upper limb predictions in stroke rehabilitation, by combining clinical measures and biomarkers using t...
Article
The laterality of the lesioned hemisphere is often overlooked in stroke recovery research due to small sample sizes. Here, we used a well-powered dataset from ENIGMA Stroke Recovery (a consortium that harmonizes post-stroke MRIs and behavioral data worldwide; http://enigma.usc.edu) to analyze the effects of left (LHL) versus right (RHL) hemisphere...
Article
Independence after stroke depends on the recovery of motor function, but this is difficult to accurately predict for individual patients. We have previously described an algorithm for predicting potential for recovery of upper limb function for individual patients after stroke. The Predict REcovery Potential (PREP) algorithm begins with a bedside a...
Article
Background and purpose: Recovery of upper-limb motor impairment after first-ever ischemic stroke is proportional to the degree of initial impairment in patients with a functional corticospinal tract (CST). This study aimed to investigate whether proportional recovery occurs in a more clinically relevant sample including patients with intracerebral...
Article
Full-text available
Reactive response inhibition (RI) is the cancellation of a prepared response when it is no longer appropriate. Selectivity of RI can be examined by cueing the cancellation of one component of a prepared multi-component response. This substantially delays execution of other components. There is debate regarding whether this response delay is due to...
Data
The Python code and data for the models are available at https://github.com/peppi107/Response_inhibition_models. (PY)
Article
Full-text available
The use of arm weight support (WS) to optimize movement quality may be an avenue for improved upper limb stroke rehabilitation; however, the underlying neurophysiological effects of WS are not well understood. Rehabilitation exercises may be performed when sitting or standing, but the interaction of posture with WS has not been examined until now....
Article
Full-text available
Aerobic exercise can enhance neuroplasticity although presently the neural mechanisms underpinning these benefits remain unclear. One possible mechanism is through effects on primary motor cortex (M1) function via down-regulation of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). The aim of the present study was to examine how corti...
Article
Full-text available
The selective serotonin reuptake inhibitor fluoxetine significantly enhances adult visual cortex plasticity within the rat. This effect is related to decreased gamma-aminobutyric acid (GABA) mediated inhibition and identifies fluoxetine as a potential agent for enhancing plasticity in the adult human brain. We tested the hypothesis that fluoxetine...
Article
Paired-pulse transcranial magnetic stimulation (TMS) can be used to probe inhibitory activity in primary motor cortex (M1). Recruitment of descending volleys with TMS depends on the induced current direction in M1. Anterior-posterior (AP) stimulation preferentially activates late indirect- (I-) waves that are most susceptible to paired-pulse TMS. T...
Article
Daily activities often require sudden cancellation of pre-planned movement, termed response inhibition. When only a subcomponent of a whole response must be suppressed (required herein on Partial trials), the ensuing component is markedly delayed. The neural mechanisms underlying partial response inhibition remain unclear. We hypothesized that Part...
Article
Full-text available
Dual-hemisphere transcranial direct current stimulation over the primary motor cortex (M1-M1 tDCS) is assumed to modulate neural excitability in a polarity-dependent manner and improve motor performance of the hand. In the proximal upper limb, the neurophysiological and behavioural after-effects of M1-M1 tDCS are not well known. This study investig...
Article
Marked distortions in sense of agency can be induced by hypnosis in susceptible individuals, including alterations in subjective awareness of movement initiation and control. These distortions, with associated disability, are similar to those experienced with Conversion Disorder (CD), an observation that has led to the hypothesis that hypnosis and...
Article
Background: Recovery of upper limb function is important for regaining independence after stroke. Objective. To test the effects of priming upper limb physical therapy with intermittent theta burst stimulation (iTBS), a form of noninvasive brain stimulation. Methods: Eighteen adults with first-ever chronic monohemispheric subcortical stroke partici...
Article
Dopamine agonists can impair inhibitory control and cause impulse control disorders for those with Parkinson's disease (PD), although mechanistically this is not well understood. In this study, we hypothesized that the extent of such drug effects on impulse control is related to specific dopamine gene polymorphisms. This double-blind, placebo-contr...
Article
The aim of this work was to explore whether selective muscle activation of the biceps brachii (BB) is modified by cathodal transcranial direct current stimulation (c-tDCS) in a movement frequency-dependent manner. Seventeen healthy participants were asked to perform repetitive isometric elbow flexion and forearm pronation at 0.75, 1.0, and 1.25 Hz,...