Nada Signal | Auckland University of Technology (original) (raw)

Papers by Nada Signal

Despite a proliferation of new rehabilitation technologies and a developing body of clinical evid... more Despite a proliferation of new rehabilitation technologies and a developing body of clinical evidence supporting their efficacy over the past 15 years, the uptake of rehabilitation technologies into clinical practice has been poor. In this qualitative study, we interviewed twenty seven rehabilitation clinicians to explore what helps and hinders the uptake of rehabilitation technologies into clinical practice. The findings illustrate that three inter-related factors are at play; the extent to which the technology addresses a clinical need, its clinical effectiveness and its usability. However, the interaction and weighting of these factors is influenced by the clinicians’ beliefs about the purpose of rehabilitation and what constitutes ‘valid’ rehabilitation practice, perceived professional roles, and whose perspective is given priority when evaluating technology. Understanding the context, process and values which drive decision-making may support the development of technologies whi...

Brain Sciences

Voluntary activation (VA) is measured by applying supramaximal electrical stimulation to a muscle... more Voluntary activation (VA) is measured by applying supramaximal electrical stimulation to a muscle during a maximal voluntary contraction (MVC). The amplitude of the evoked muscle twitch is used to determine any VA deficit, and indicates incomplete central neural drive to the motor units. People with stroke experience VA deficits and greater levels of central fatigue, which is the decrease in VA that occurs following exercise. This study investigated the between-session reliability of VA and central fatigue of the tibialis anterior muscle (TA) in people with chronic stroke (n = 12), using the interpolated twitch technique (ITT), adjusted-ITT, and central activation ratio (CAR) methods. On two separate sessions, supramaximal electrical stimulation was applied to the TA when it was at rest and maximally activated, at the start and end of a 30-s isometric dorsiflexor MVC. The most reliable measures of VA were obtained using the CAR calculation on transformed data, which produced an ICC ...

Brain Sciences

Advances in our understanding of neural plasticity have prompted the emergence of neuromodulatory... more Advances in our understanding of neural plasticity have prompted the emergence of neuromodulatory interventions, which modulate corticomotor excitability (CME) and hold potential for accelerating stroke recovery. Endogenous paired associative stimulation (ePAS) involves the repeated pairing of a single pulse of peripheral electrical stimulation (PES) with endogenous movement-related cortical potentials (MRCPs), which are derived from electroencephalography. However, little is known about the optimal parameters for its delivery. A factorial design with repeated measures delivered four different versions of ePAS, in which PES intensities and movement type were manipulated. Linear mixed models were employed to assess interaction effects between PES intensity (suprathreshold (Hi) and motor threshold (Lo)) and movement type (Voluntary and Imagined) on CME. ePAS interventions significantly increased CME compared to control interventions, except in the case of Lo-Voluntary ePAS. There was ...

New Zealand Journal of Physiotherapy

The health response to the COVID-19 pandemic has had significant impacts on neurorehabilitation p... more The health response to the COVID-19 pandemic has had significant impacts on neurorehabilitation provision both internationally and in New Zealand. Telerehabilitation, the delivery of rehabilitation at a distance using information and communication technologies, was advocated as a means of addressing the rehabilitation needs of our patients while maintaining physical distancing and reducing the risk of viral transmission. Despite research evidence indicating that telerehabilitation is as effective as in-person rehabilitation for people with neurological conditions, there were significant challenges in delivering and sustaining telerehabilitation practice. We draw upon our experiences in delivering telerehabilitation in neurorehabilitation clinical practice and education to reflect on the process of practice change and to consider how these experiences can inform practice development in the future. We propose that rehabilitation organisations and physiotherapists continue to develop capability to provide telerehabilitation; that physiotherapists and the physiotherapy profession focus on translating their communicative, relational and clinical skills to the digital space to ensure they are competent in telerehabilitation; and that, as a profession, we focus on what constitutes "best practice" in telerehabilitation, and how in-person and telerehabilitation can be integrated to provide engaging, evidence-based and person-centred rehabilitation.

Journal of Clinical Medicine

Ankle and foot orthoses are commonly prescribed to children with cerebral palsy (CP). It is uncle... more Ankle and foot orthoses are commonly prescribed to children with cerebral palsy (CP). It is unclear whether 3D gait analysis (3DGA) provides sufficient and reliable information for clinicians to be consistent when prescribing orthoses. Data-driven modeling can probe such questions by revealing non-intuitive relationships between variables such as 3DGA parameters and gait outcomes of orthoses use. The purpose of this study was to (1) develop a data-driven model to classify children with CP according to their gait biomechanics and (2) identify relationships between orthotics types and gait patterns. 3DGA data were acquired from walking trials of 25 typically developed children and 98 children with CP with additional prescribed orthoses. An unsupervised self-organizing map followed by k-means clustering was developed to group different gait patterns based on children’s 3DGA. Model inputs were gait variable scores (GVSs) extracted from the gait profile score, measuring root mean square ...

BACKGROUND As many as 80% of stroke survivors experience upper limb (UL) disability. The strong r... more BACKGROUND As many as 80% of stroke survivors experience upper limb (UL) disability. The strong relationships between disability, lost productivity, and ongoing healthcare costs mean reducing disability after stroke is critical at both individual and society levels. Unfortunately, the amount of UL-focused rehabilitation received by people with stroke is extremely low. Activity monitoring and promotion using wearable devices offers a potential technology-based solution to address this gap. Commonly, wearable devices are used to deliver a haptic nudge to the wearer with the aim of promoting a particular behavior. However, little is known about the effectiveness of haptic nudging in promoting behaviors in patient populations. OBJECTIVE To estimate the effect of haptic nudging delivered via a wrist worn wearable device on UL movement in people with upper limb disability following stroke undertaking inpatient rehabilitation. METHODS A multiple-period randomized crossover design was used ...

Journal of Electromyography and Kinesiology

A significant challenge in surface electromyography (sEMG) is the accurate identification of onse... more A significant challenge in surface electromyography (sEMG) is the accurate identification of onsets and offsets of muscle activations. Manual labelling and automatic detection are currently used with varying degrees of reliability, accuracy and time efficiency. Automatic methods still require significant manual input to set the optimal parameters for the detection algorithm. These parameters usually need to be adjusted for each individual, muscle and movement task. We propose a method to automatically identify optimal detection parameters in a minimally supervised way. The proposed method solves an optimisation problem that only requires as input the number of activation bursts in the sEMG in a given time interval. This approach was tested on an extended version of the widely adopted double thresholding algorithm, although the optimisation could be applied to any detection algorithm. sEMG data from 22 healthy participants performing a single (ankle dorsiflexion) and a multi-joint (step on/off) task were used for evaluation. Detection rate, concordance, F1 score as an average of sensitivity and precision, degree of over detection, and degree of under detection were used as performance metrices. The proposed method improved the performance of the double thresholding algorithm in multi-joint movement and had the same performance in single joint movement with respect to the performance of the double thresholding algorithm with task specific global parameters. Moreover, the proposed method was robust when an error of up to ±10% was introduced in the number of activation bursts in the optimisation phase regardless of the movement. In conclusion, our optimised method has improved the automation of a sEMG detection algorithm which may reduce the time burden associated with current sEMG processing.

Brain Sciences

Brain-computer interfaces (BCIs), operated in a cue-based (offline) or self-paced (online) mode, ... more Brain-computer interfaces (BCIs), operated in a cue-based (offline) or self-paced (online) mode, can be used for inducing cortical plasticity for stroke rehabilitation by the pairing of movement-related brain activity with peripheral electrical stimulation. The aim of this study was to compare the difference in cortical plasticity induced by the two BCI modes. Fifteen healthy participants participated in two experimental sessions: cue-based BCI and self-paced BCI. In both sessions, imagined dorsiflexions were extracted from continuous electroencephalogram (EEG) and paired 50 times with the electrical stimulation of the common peroneal nerve. Before, immediately after, and 30 minutes after each intervention, the cortical excitability was measured through the motor-evoked potentials (MEPs) of tibialis anterior elicited through transcranial magnetic stimulation. Linear mixed regression models showed that the MEP amplitudes increased significantly (p < 0.05) from pre-to post-and 30-minutes post-intervention in terms of both the absolute and relative units, regardless of the intervention type. Compared to pre-interventions, the absolute MEP size increased by 79% in post-and 68% in 30-minutes post-intervention in the selfpaced mode (with a true positive rate of ~75%), and by 37% in post-and 55% in 30-minutes postintervention in the cue-based mode. The two modes were significantly different (p = 0.03) at postintervention (relative units) but were similar at both post timepoints (absolute units). These findings suggest that immediate changes in cortical excitability may have implications for stroke rehabilitation, where it could be used as a priming protocol in conjunction with another intervention; however, the findings need to be validated in studies involving stroke patients.

Sensors

Texas Instruments ADS1299 is an attractive choice for low cost electroencephalography (EEG) devic... more Texas Instruments ADS1299 is an attractive choice for low cost electroencephalography (EEG) devices owing to its low power consumption and low input referred noise. To date, there have been no rigorous evaluations of its performance. In this EEG experimental study we evaluated the performance of the ADS1299 against a high quality laboratory-based system. Two self-paced lower limb motor tasks were performed by 22 healthy participants. Recorded power across delta, theta, alpha, and beta EEG bands, the power ratio across the motor tasks, pre-movement noise, and signal-to-noise ratio were obtained for evaluation. The amplitude and time of the negative peak in the movement-related cortical potentials (MRCPs) extracted from the EEG data were also obtained. Using linear mixed models, no statistically significant differences (p > 0.05) were found in any of these measures across the two systems. These findings were further supported by evaluation of cosine similarity, waveform differences...

Journal of neuroengineering and rehabilitation, Jun 19, 2017

The RAPPER II study investigates the feasibility, safety and acceptability of using the REX self-... more The RAPPER II study investigates the feasibility, safety and acceptability of using the REX self-stabilising robotic exoskeleton in people with spinal cord injury (SCI) who are obligatory wheelchair users. Feasibility is assessed by the completion of transfer into the REX device, competency in achieving autonomous control and completion of upper body exercise in an upright position in the REX device. Safety is measured by the occurrence of serious adverse events. Device acceptability is assessed with a user questionnaire. RAPPER II is a prospective, multi-centre, open label, non-randomised, non-comparative cohort study in people with SCI recruited from neurological rehabilitation centres in the United Kingdom, Australia and New Zealand. This is the planned interim report of the first 20 participants. Each completed a transfer into the REX, were trained to achieve machine control and completed Timed Up and Go (TUG) tests as well as upper body exercises in standing in a single first t...

BMJ open, Jan 13, 2016

To enhance understanding of the experiences of ageing with cerebral palsy (CP) in adulthood with ... more To enhance understanding of the experiences of ageing with cerebral palsy (CP) in adulthood with a particular focus on experiences with health services. A qualitative descriptive methodology was applied to capture adults' views of ageing with CP and related interactions with health services. Semistructured interviews were undertaken with data systematically coded and interpreted by grouping information into categories. Themes that encompassed the categories were identified through thematic analysis. All healthcare settings. 28 adults (14 women) with CP, aged 37-70 years. 5 themes covered the breadth of participants' experiences: (1) acceptance of change; (2) exploring identity: cerebral palsy as only one part of self; (3) taking charge of help; (4) rethinking the future and (5) interacting with health professionals. Being seen and being heard were the features described in positive healthcare interactions. Participants also valued health professionals who reflected on who ho...

Frontiers in Human Neuroscience, 2016

Learning new motor skills has been correlated with increased cortical excitability. In this study... more Learning new motor skills has been correlated with increased cortical excitability. In this study, different location of electrical stimulation (ES), nerve, or muscle, was paired with voluntary movement to investigate if ES paired with voluntary movement (a) would increase the excitability of cortical projections to tibialis anterior and (b) if stimulation location mattered. Cortical excitability changes were quantified using motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) at varying intensities during four conditions. Twelve healthy subjects performed 50 dorsiflexions at the ankle during nerve or muscle ES at motor threshold (MTh). ES alone was delivered 50 times and the movement was performed 50 times. A significant increase in the excitability from pre-to post-intervention (P = 0.0061) and pre-to 30 min post-intervention (P = 0.017) measurements was observed when voluntary movement was paired with muscle ES located at tibialis anterior. An increase of 50 ± 57 and 28 ± 54% in the maximum MEPs was obtained for voluntary movement paired with muscle-located and nerve-located ES, respectively. The maximum MEPs for voluntary movement alone and muscle-located ES alone were −5 ± 28 and 2 ± 42%, respectively. Pairing voluntary movement with muscle-located ES increases excitability of corticospinal projections of tibialis anterior in healthy participants. This finding suggests that active participation during muscle-located ES protocols increases cortical excitability to a greater extent than stimulation alone. The next stage of this research is to investigate the effect in people with stroke. The results may have implications for motor recovery in patients with motor impairments following neurological injury.

NeuroRehabilitation, Jan 27, 2016

Intensity refers to the amount of effort or rate of work undertaken during exercise. People recei... more Intensity refers to the amount of effort or rate of work undertaken during exercise. People receiving rehabilitation after stroke frequently do not reach the moderate to high intensity exercise recommended to maximise gains. To explore the factors that influence the acceptability of, and engagement with, a high intensity group-based exercise programme for people with stroke. This qualitative descriptive study included 14 people with stroke who had completed a 12-week, high intensity group-based exercise rehabilitation programme. Semi-structured interviews were used to explore the acceptability of high intensity exercise and the barriers and facilitators to engagement. Interviews were recorded, transcribed and analysed using qualitative content analysis. The participants found high intensity exercise rehabilitation acceptable despite describing the exercise intensity as hard and reporting post-exercise fatigue. Participants accepted the fatigue as a normal response to exercise, and i...

Aim: The aim of this study was to examine and compare the contribution of central neuromuscular f... more Aim: The aim of this study was to examine and compare the contribution of central neuromuscular fatigue and peripheral neuromuscular fatigue to total neuromuscular fatigue in the hemiplegic leg of people with stroke, with that of a matched control group. Study Design: This experimental study utilised a repeated measures block design. Participants: Fifteen people with chronic stroke who had mild to moderate physical disability and fifteen age, height and weight matched controls were compared. Main outcome measures Participants physical function was evaluated using the 30s Chair Stand Test, Comfortable Paced Walking Speed and Fast Paced Walking Speed. Neuromuscular function was measured using maximal voluntary isometric contraction force and voluntary activation. Total neuromuscular fatigue, central neuromuscular fatigue and peripheral neuromuscular fatigue was measured during a 90 second sustained maximal voluntary isometric contraction of the quadriceps muscle. Results: The fatigue profile of stroke participants differed from that of control participants. Stroke participants demonstrated less total neuromuscular fatigue (U=41.00, p=.026) and less peripheral neuromuscular fatigue (U=14.00, p=.000) than the control participants. While stroke participants did demonstrate greater central neuromuscular fatigue than control participants, this finding was not statistically significant (U=80.00, p=.817). Conclusions: Statistically significant differences were found in the performance of people with mild to moderate physical disability following stroke on measures of neuromuscular fatigue when compared to age, weight and height matched healthy adults.

New Zealand Journal of Physiotherapy, Nov 1, 2009

Brain Sciences

Single and double exponential models fitted to step length symmetry series are used to evaluate t... more Single and double exponential models fitted to step length symmetry series are used to evaluate the timecourse of adaptation and de-adaptation in instrumented split-belt treadmill tasks. Whilst the nonlinear regression literature has developed substantially over time, the split-belt treadmill training literature has not been fully utilising the fruits of these developments. In this research area, the current methods of model fitting and evaluation have three significant limitations: (i) optimisation algorithms that are used for model fitting require a good initial guess for regression parameters; (ii) the coefficient of determination (R2) is used for comparing and evaluating models, yet it is considered to be an inadequate measure of fit for nonlinear regression; and, (iii) inference is based on comparison of the confidence intervals for the regression parameters that are obtained under the untested assumption that the nonlinear model has a good linear approximation. In this researc...

Many people with stroke have ongoing difficulty with locomotor abilities to the extent that it li... more Many people with stroke have ongoing difficulty with locomotor abilities to the extent that it limits their participation in meaningful community life. Deficits in locomotor ability are strongly related to muscle weakness following stroke. Whilst the majority of physical therapy time is spent on the rehabilitation of locomotor abilities, the most effective rehabilitation method has yet to be determined. The need to develop efficacious rehabilitation strategies to address locomotor disability following stroke is paramount.

Frontiers in Human Neuroscience, 2015

Long-term depression (LTD) and long-term potentiation (LTP)-like plasticity are models of synapti... more Long-term depression (LTD) and long-term potentiation (LTP)-like plasticity are models of synaptic plasticity which have been associated with memory and learning. The induction of LTD and LTP-like plasticity, using different stimulation protocols, has been proposed as a means of addressing abnormalities in cortical excitability associated with conditions such as focal hand dystonia and stroke. The aim of this study was to investigate whether the excitability of the cortical projections to the tibialis anterior (TA) muscle could be decreased when dorsiflexion of the ankle joint was imagined and paired with peripheral electrical stimulation (ES) of the nerve supplying the antagonist soleus muscle. The effect of stimulus timing was evaluated by comparing paired stimulation timed to reach the cortex before, at and after the onset of imagined movement. Fourteen healthy subjects participated in six experimental sessions held on non-consecutive days. The timing of stimulation delivery was determined offline based on the contingent negative variation (CNV) of electroencephalography brain data obtained during imagined dorsiflexion. Afferent stimulation was provided via a single pulse ES to the peripheral nerve paired, based on the CNV, with motor imagination of ankle dorsiflexion. A significant decrease (P = 0.001) in the excitability of the cortical projection of TA was observed when the afferent volley from the ES of the tibial nerve (TN) reached the cortex at the onset of motor imagination based on the CNV. When TN stimulation was delivered before (P = 0.62), or after (P = 0.23) imagined movement onset there was no significant effect. Nor was a significant effect found when ES of the TN was applied independent of imagined movement (P = 0.45). Therefore, the excitability of the cortical projection to a muscle can be inhibited when ES of the nerve supplying the antagonist muscle is precisely paired with the onset of imagined movement.

Despite a proliferation of new rehabilitation technologies and a developing body of clinical evid... more Despite a proliferation of new rehabilitation technologies and a developing body of clinical evidence supporting their efficacy over the past 15 years, the uptake of rehabilitation technologies into clinical practice has been poor. In this qualitative study, we interviewed twenty seven rehabilitation clinicians to explore what helps and hinders the uptake of rehabilitation technologies into clinical practice. The findings illustrate that three inter-related factors are at play; the extent to which the technology addresses a clinical need, its clinical effectiveness and its usability. However, the interaction and weighting of these factors is influenced by the clinicians’ beliefs about the purpose of rehabilitation and what constitutes ‘valid’ rehabilitation practice, perceived professional roles, and whose perspective is given priority when evaluating technology. Understanding the context, process and values which drive decision-making may support the development of technologies whi...

Brain Sciences

Voluntary activation (VA) is measured by applying supramaximal electrical stimulation to a muscle... more Voluntary activation (VA) is measured by applying supramaximal electrical stimulation to a muscle during a maximal voluntary contraction (MVC). The amplitude of the evoked muscle twitch is used to determine any VA deficit, and indicates incomplete central neural drive to the motor units. People with stroke experience VA deficits and greater levels of central fatigue, which is the decrease in VA that occurs following exercise. This study investigated the between-session reliability of VA and central fatigue of the tibialis anterior muscle (TA) in people with chronic stroke (n = 12), using the interpolated twitch technique (ITT), adjusted-ITT, and central activation ratio (CAR) methods. On two separate sessions, supramaximal electrical stimulation was applied to the TA when it was at rest and maximally activated, at the start and end of a 30-s isometric dorsiflexor MVC. The most reliable measures of VA were obtained using the CAR calculation on transformed data, which produced an ICC ...

Brain Sciences

Advances in our understanding of neural plasticity have prompted the emergence of neuromodulatory... more Advances in our understanding of neural plasticity have prompted the emergence of neuromodulatory interventions, which modulate corticomotor excitability (CME) and hold potential for accelerating stroke recovery. Endogenous paired associative stimulation (ePAS) involves the repeated pairing of a single pulse of peripheral electrical stimulation (PES) with endogenous movement-related cortical potentials (MRCPs), which are derived from electroencephalography. However, little is known about the optimal parameters for its delivery. A factorial design with repeated measures delivered four different versions of ePAS, in which PES intensities and movement type were manipulated. Linear mixed models were employed to assess interaction effects between PES intensity (suprathreshold (Hi) and motor threshold (Lo)) and movement type (Voluntary and Imagined) on CME. ePAS interventions significantly increased CME compared to control interventions, except in the case of Lo-Voluntary ePAS. There was ...

New Zealand Journal of Physiotherapy

The health response to the COVID-19 pandemic has had significant impacts on neurorehabilitation p... more The health response to the COVID-19 pandemic has had significant impacts on neurorehabilitation provision both internationally and in New Zealand. Telerehabilitation, the delivery of rehabilitation at a distance using information and communication technologies, was advocated as a means of addressing the rehabilitation needs of our patients while maintaining physical distancing and reducing the risk of viral transmission. Despite research evidence indicating that telerehabilitation is as effective as in-person rehabilitation for people with neurological conditions, there were significant challenges in delivering and sustaining telerehabilitation practice. We draw upon our experiences in delivering telerehabilitation in neurorehabilitation clinical practice and education to reflect on the process of practice change and to consider how these experiences can inform practice development in the future. We propose that rehabilitation organisations and physiotherapists continue to develop capability to provide telerehabilitation; that physiotherapists and the physiotherapy profession focus on translating their communicative, relational and clinical skills to the digital space to ensure they are competent in telerehabilitation; and that, as a profession, we focus on what constitutes "best practice" in telerehabilitation, and how in-person and telerehabilitation can be integrated to provide engaging, evidence-based and person-centred rehabilitation.

Journal of Clinical Medicine

Ankle and foot orthoses are commonly prescribed to children with cerebral palsy (CP). It is uncle... more Ankle and foot orthoses are commonly prescribed to children with cerebral palsy (CP). It is unclear whether 3D gait analysis (3DGA) provides sufficient and reliable information for clinicians to be consistent when prescribing orthoses. Data-driven modeling can probe such questions by revealing non-intuitive relationships between variables such as 3DGA parameters and gait outcomes of orthoses use. The purpose of this study was to (1) develop a data-driven model to classify children with CP according to their gait biomechanics and (2) identify relationships between orthotics types and gait patterns. 3DGA data were acquired from walking trials of 25 typically developed children and 98 children with CP with additional prescribed orthoses. An unsupervised self-organizing map followed by k-means clustering was developed to group different gait patterns based on children’s 3DGA. Model inputs were gait variable scores (GVSs) extracted from the gait profile score, measuring root mean square ...

BACKGROUND As many as 80% of stroke survivors experience upper limb (UL) disability. The strong r... more BACKGROUND As many as 80% of stroke survivors experience upper limb (UL) disability. The strong relationships between disability, lost productivity, and ongoing healthcare costs mean reducing disability after stroke is critical at both individual and society levels. Unfortunately, the amount of UL-focused rehabilitation received by people with stroke is extremely low. Activity monitoring and promotion using wearable devices offers a potential technology-based solution to address this gap. Commonly, wearable devices are used to deliver a haptic nudge to the wearer with the aim of promoting a particular behavior. However, little is known about the effectiveness of haptic nudging in promoting behaviors in patient populations. OBJECTIVE To estimate the effect of haptic nudging delivered via a wrist worn wearable device on UL movement in people with upper limb disability following stroke undertaking inpatient rehabilitation. METHODS A multiple-period randomized crossover design was used ...

Journal of Electromyography and Kinesiology

A significant challenge in surface electromyography (sEMG) is the accurate identification of onse... more A significant challenge in surface electromyography (sEMG) is the accurate identification of onsets and offsets of muscle activations. Manual labelling and automatic detection are currently used with varying degrees of reliability, accuracy and time efficiency. Automatic methods still require significant manual input to set the optimal parameters for the detection algorithm. These parameters usually need to be adjusted for each individual, muscle and movement task. We propose a method to automatically identify optimal detection parameters in a minimally supervised way. The proposed method solves an optimisation problem that only requires as input the number of activation bursts in the sEMG in a given time interval. This approach was tested on an extended version of the widely adopted double thresholding algorithm, although the optimisation could be applied to any detection algorithm. sEMG data from 22 healthy participants performing a single (ankle dorsiflexion) and a multi-joint (step on/off) task were used for evaluation. Detection rate, concordance, F1 score as an average of sensitivity and precision, degree of over detection, and degree of under detection were used as performance metrices. The proposed method improved the performance of the double thresholding algorithm in multi-joint movement and had the same performance in single joint movement with respect to the performance of the double thresholding algorithm with task specific global parameters. Moreover, the proposed method was robust when an error of up to ±10% was introduced in the number of activation bursts in the optimisation phase regardless of the movement. In conclusion, our optimised method has improved the automation of a sEMG detection algorithm which may reduce the time burden associated with current sEMG processing.

Brain Sciences

Brain-computer interfaces (BCIs), operated in a cue-based (offline) or self-paced (online) mode, ... more Brain-computer interfaces (BCIs), operated in a cue-based (offline) or self-paced (online) mode, can be used for inducing cortical plasticity for stroke rehabilitation by the pairing of movement-related brain activity with peripheral electrical stimulation. The aim of this study was to compare the difference in cortical plasticity induced by the two BCI modes. Fifteen healthy participants participated in two experimental sessions: cue-based BCI and self-paced BCI. In both sessions, imagined dorsiflexions were extracted from continuous electroencephalogram (EEG) and paired 50 times with the electrical stimulation of the common peroneal nerve. Before, immediately after, and 30 minutes after each intervention, the cortical excitability was measured through the motor-evoked potentials (MEPs) of tibialis anterior elicited through transcranial magnetic stimulation. Linear mixed regression models showed that the MEP amplitudes increased significantly (p < 0.05) from pre-to post-and 30-minutes post-intervention in terms of both the absolute and relative units, regardless of the intervention type. Compared to pre-interventions, the absolute MEP size increased by 79% in post-and 68% in 30-minutes post-intervention in the selfpaced mode (with a true positive rate of ~75%), and by 37% in post-and 55% in 30-minutes postintervention in the cue-based mode. The two modes were significantly different (p = 0.03) at postintervention (relative units) but were similar at both post timepoints (absolute units). These findings suggest that immediate changes in cortical excitability may have implications for stroke rehabilitation, where it could be used as a priming protocol in conjunction with another intervention; however, the findings need to be validated in studies involving stroke patients.

Sensors

Texas Instruments ADS1299 is an attractive choice for low cost electroencephalography (EEG) devic... more Texas Instruments ADS1299 is an attractive choice for low cost electroencephalography (EEG) devices owing to its low power consumption and low input referred noise. To date, there have been no rigorous evaluations of its performance. In this EEG experimental study we evaluated the performance of the ADS1299 against a high quality laboratory-based system. Two self-paced lower limb motor tasks were performed by 22 healthy participants. Recorded power across delta, theta, alpha, and beta EEG bands, the power ratio across the motor tasks, pre-movement noise, and signal-to-noise ratio were obtained for evaluation. The amplitude and time of the negative peak in the movement-related cortical potentials (MRCPs) extracted from the EEG data were also obtained. Using linear mixed models, no statistically significant differences (p > 0.05) were found in any of these measures across the two systems. These findings were further supported by evaluation of cosine similarity, waveform differences...

Journal of neuroengineering and rehabilitation, Jun 19, 2017

The RAPPER II study investigates the feasibility, safety and acceptability of using the REX self-... more The RAPPER II study investigates the feasibility, safety and acceptability of using the REX self-stabilising robotic exoskeleton in people with spinal cord injury (SCI) who are obligatory wheelchair users. Feasibility is assessed by the completion of transfer into the REX device, competency in achieving autonomous control and completion of upper body exercise in an upright position in the REX device. Safety is measured by the occurrence of serious adverse events. Device acceptability is assessed with a user questionnaire. RAPPER II is a prospective, multi-centre, open label, non-randomised, non-comparative cohort study in people with SCI recruited from neurological rehabilitation centres in the United Kingdom, Australia and New Zealand. This is the planned interim report of the first 20 participants. Each completed a transfer into the REX, were trained to achieve machine control and completed Timed Up and Go (TUG) tests as well as upper body exercises in standing in a single first t...

BMJ open, Jan 13, 2016

To enhance understanding of the experiences of ageing with cerebral palsy (CP) in adulthood with ... more To enhance understanding of the experiences of ageing with cerebral palsy (CP) in adulthood with a particular focus on experiences with health services. A qualitative descriptive methodology was applied to capture adults' views of ageing with CP and related interactions with health services. Semistructured interviews were undertaken with data systematically coded and interpreted by grouping information into categories. Themes that encompassed the categories were identified through thematic analysis. All healthcare settings. 28 adults (14 women) with CP, aged 37-70 years. 5 themes covered the breadth of participants' experiences: (1) acceptance of change; (2) exploring identity: cerebral palsy as only one part of self; (3) taking charge of help; (4) rethinking the future and (5) interacting with health professionals. Being seen and being heard were the features described in positive healthcare interactions. Participants also valued health professionals who reflected on who ho...

Frontiers in Human Neuroscience, 2016

Learning new motor skills has been correlated with increased cortical excitability. In this study... more Learning new motor skills has been correlated with increased cortical excitability. In this study, different location of electrical stimulation (ES), nerve, or muscle, was paired with voluntary movement to investigate if ES paired with voluntary movement (a) would increase the excitability of cortical projections to tibialis anterior and (b) if stimulation location mattered. Cortical excitability changes were quantified using motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) at varying intensities during four conditions. Twelve healthy subjects performed 50 dorsiflexions at the ankle during nerve or muscle ES at motor threshold (MTh). ES alone was delivered 50 times and the movement was performed 50 times. A significant increase in the excitability from pre-to post-intervention (P = 0.0061) and pre-to 30 min post-intervention (P = 0.017) measurements was observed when voluntary movement was paired with muscle ES located at tibialis anterior. An increase of 50 ± 57 and 28 ± 54% in the maximum MEPs was obtained for voluntary movement paired with muscle-located and nerve-located ES, respectively. The maximum MEPs for voluntary movement alone and muscle-located ES alone were −5 ± 28 and 2 ± 42%, respectively. Pairing voluntary movement with muscle-located ES increases excitability of corticospinal projections of tibialis anterior in healthy participants. This finding suggests that active participation during muscle-located ES protocols increases cortical excitability to a greater extent than stimulation alone. The next stage of this research is to investigate the effect in people with stroke. The results may have implications for motor recovery in patients with motor impairments following neurological injury.

NeuroRehabilitation, Jan 27, 2016

Intensity refers to the amount of effort or rate of work undertaken during exercise. People recei... more Intensity refers to the amount of effort or rate of work undertaken during exercise. People receiving rehabilitation after stroke frequently do not reach the moderate to high intensity exercise recommended to maximise gains. To explore the factors that influence the acceptability of, and engagement with, a high intensity group-based exercise programme for people with stroke. This qualitative descriptive study included 14 people with stroke who had completed a 12-week, high intensity group-based exercise rehabilitation programme. Semi-structured interviews were used to explore the acceptability of high intensity exercise and the barriers and facilitators to engagement. Interviews were recorded, transcribed and analysed using qualitative content analysis. The participants found high intensity exercise rehabilitation acceptable despite describing the exercise intensity as hard and reporting post-exercise fatigue. Participants accepted the fatigue as a normal response to exercise, and i...

Aim: The aim of this study was to examine and compare the contribution of central neuromuscular f... more Aim: The aim of this study was to examine and compare the contribution of central neuromuscular fatigue and peripheral neuromuscular fatigue to total neuromuscular fatigue in the hemiplegic leg of people with stroke, with that of a matched control group. Study Design: This experimental study utilised a repeated measures block design. Participants: Fifteen people with chronic stroke who had mild to moderate physical disability and fifteen age, height and weight matched controls were compared. Main outcome measures Participants physical function was evaluated using the 30s Chair Stand Test, Comfortable Paced Walking Speed and Fast Paced Walking Speed. Neuromuscular function was measured using maximal voluntary isometric contraction force and voluntary activation. Total neuromuscular fatigue, central neuromuscular fatigue and peripheral neuromuscular fatigue was measured during a 90 second sustained maximal voluntary isometric contraction of the quadriceps muscle. Results: The fatigue profile of stroke participants differed from that of control participants. Stroke participants demonstrated less total neuromuscular fatigue (U=41.00, p=.026) and less peripheral neuromuscular fatigue (U=14.00, p=.000) than the control participants. While stroke participants did demonstrate greater central neuromuscular fatigue than control participants, this finding was not statistically significant (U=80.00, p=.817). Conclusions: Statistically significant differences were found in the performance of people with mild to moderate physical disability following stroke on measures of neuromuscular fatigue when compared to age, weight and height matched healthy adults.

New Zealand Journal of Physiotherapy, Nov 1, 2009

Brain Sciences

Single and double exponential models fitted to step length symmetry series are used to evaluate t... more Single and double exponential models fitted to step length symmetry series are used to evaluate the timecourse of adaptation and de-adaptation in instrumented split-belt treadmill tasks. Whilst the nonlinear regression literature has developed substantially over time, the split-belt treadmill training literature has not been fully utilising the fruits of these developments. In this research area, the current methods of model fitting and evaluation have three significant limitations: (i) optimisation algorithms that are used for model fitting require a good initial guess for regression parameters; (ii) the coefficient of determination (R2) is used for comparing and evaluating models, yet it is considered to be an inadequate measure of fit for nonlinear regression; and, (iii) inference is based on comparison of the confidence intervals for the regression parameters that are obtained under the untested assumption that the nonlinear model has a good linear approximation. In this researc...

Many people with stroke have ongoing difficulty with locomotor abilities to the extent that it li... more Many people with stroke have ongoing difficulty with locomotor abilities to the extent that it limits their participation in meaningful community life. Deficits in locomotor ability are strongly related to muscle weakness following stroke. Whilst the majority of physical therapy time is spent on the rehabilitation of locomotor abilities, the most effective rehabilitation method has yet to be determined. The need to develop efficacious rehabilitation strategies to address locomotor disability following stroke is paramount.

Frontiers in Human Neuroscience, 2015

Long-term depression (LTD) and long-term potentiation (LTP)-like plasticity are models of synapti... more Long-term depression (LTD) and long-term potentiation (LTP)-like plasticity are models of synaptic plasticity which have been associated with memory and learning. The induction of LTD and LTP-like plasticity, using different stimulation protocols, has been proposed as a means of addressing abnormalities in cortical excitability associated with conditions such as focal hand dystonia and stroke. The aim of this study was to investigate whether the excitability of the cortical projections to the tibialis anterior (TA) muscle could be decreased when dorsiflexion of the ankle joint was imagined and paired with peripheral electrical stimulation (ES) of the nerve supplying the antagonist soleus muscle. The effect of stimulus timing was evaluated by comparing paired stimulation timed to reach the cortex before, at and after the onset of imagined movement. Fourteen healthy subjects participated in six experimental sessions held on non-consecutive days. The timing of stimulation delivery was determined offline based on the contingent negative variation (CNV) of electroencephalography brain data obtained during imagined dorsiflexion. Afferent stimulation was provided via a single pulse ES to the peripheral nerve paired, based on the CNV, with motor imagination of ankle dorsiflexion. A significant decrease (P = 0.001) in the excitability of the cortical projection of TA was observed when the afferent volley from the ES of the tibial nerve (TN) reached the cortex at the onset of motor imagination based on the CNV. When TN stimulation was delivered before (P = 0.62), or after (P = 0.23) imagined movement onset there was no significant effect. Nor was a significant effect found when ES of the TN was applied independent of imagined movement (P = 0.45). Therefore, the excitability of the cortical projection to a muscle can be inhibited when ES of the nerve supplying the antagonist muscle is precisely paired with the onset of imagined movement.