Anouk Lamontagne

McGill University, Montréal, Quebec, Canada

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Publications (72)142.95 Total impact

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    Anuja Darekar · Bradford J McFadyen · Anouk Lamontagne · Joyce Fung
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    ABSTRACT: Rehabilitation interventions involving virtual reality (VR) technology have been developed for the promotion of functional independence post stroke. A scoping review was performed to examine the efficacy of VR-based interventions on balance and mobility disorders post stroke. Twenty-four articles in the English language examining VR game-based interventions and outcomes directed at balance and mobility disorders were included. Various VR systems (customized and commercially available) were used as rehabilitation tools. Outcome measures included laboratory and clinical measures of balance and gait. Outcome measures of dynamic balance showed significant improvements following VR-based interventions as compared to other interventions. Further, it was observed that VR-based intervention may have favorable effects in improving walking speed and the ability to deal with environmental challenges, which may also facilitate independent community ambulation. VR-based therapy thus has the potential to be a useful tool for balance and gait training for stroke rehabilitation. Utilization of motor learning principles related to task-related training may have been an important factor leading to positive results. Other principles such as repetition, feedback etc. were used in studies but were not explored explicitly and may need to be investigated to further improve the strength of results. Lastly, robust study designs with appropriate attention towards the intensity and dose-response aspects of VR training, clear study objectives and suitable outcomes would further aid in determining evidence-based efficacy for VR game-based interventions in the future.
    Journal of NeuroEngineering and Rehabilitation 05/2015; 12(1). DOI:10.1186/s12984-015-0035-3 · 2.62 Impact Factor
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    Tatiana Ogourtsova · Philippe Archambault · Anouk Lamontagne
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    ABSTRACT: Unilateral spatial neglect (USN), a highly prevalent post-stroke impairment, refers to one's inability to orient or respond to stimuli located in the contralesional visual hemispace. Unilateral spatial neglect has been shown to strongly affect motor performance in functional activities, including non-affected upper extremity (UE) movements. To date, our understanding of the effects of USN on goal-directed UE movements is limited and comparing performance of individuals post-stroke with and without USN is required. To determine, in individuals with stroke, how does the presence of USN, in comparison to the absence of USN, impacts different types of goal-directed movements of the non-affected UE. The present review approach consisted of a comprehensive literature search, an assessment of the quality of the selected studies and qualitative data analysis. A total of 20 studies of moderate to high quality were selected. The USN-specific impairments were found in tasks that required a perceptual, memory-guided or delayed actions, and fewer impairments were found in tasks that required an immediate action to a predefined target. The results indicate that USN contributes to deficits observed in action execution with the non-effected UE requiring relational metrics, scene-based coordinates, and working memory component.
    Topics in Stroke Rehabilitation 04/2015; DOI:10.1179/1074935714Z.0000000046 · 1.22 Impact Factor
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    Anuja Darekar · Anouk Lamontagne · Joyce Fung
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    ABSTRACT: Circumvention around an obstacle entails a dynamic interaction with the obstacle to maintain a safe clearance. We used a novel mathematical interpolation method based on the modified Shepard’s method of Inverse Distance Weighting to compute dynamic clearance that reflected this interaction as well as minimal clearance. This proof-of-principle study included seven young healthy, four post-stroke and four healthy age-matched individuals. A virtual environment designed to assess obstacle circumvention was used to administer a locomotor (walking) and a perceptuo-motor (navigation with a joystick) task. In both tasks, participants were asked to navigate towards a target while avoiding collision with a moving obstacle that approached from either head-on, or 30� left or right. Among young individuals, dynamic clearance did not differ significantly between obstacle approach directions in both tasks. Post-stroke individuals maintained larger and smaller dynamic clearance during the locomotor and the perceptuo-motor task respectively as compared to age-matched controls. Dynamic clearance was larger than minimal distance from the obstacle irrespective of the group, task and obstacle approach direction. Also, in contrast to minimal distance, dynamic clearance can respond differently to different avoidance behaviors. Such a measure can be beneficial in contrasting obstacle avoidance behaviors in different populations with mobility problems.
    Human Movement Science 04/2015; 40:359-371. DOI:10.1016/j.humov.2015.01.010 · 2.03 Impact Factor
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    Anuja Darekar · Anouk Lamontagne · Joyce Fung
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    Gayatri Aravind · Anuja Darekar · Joyce Fung · Anouk Lamontagne
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    ABSTRACT: Persons with post-stroke visuospatial neglect (VSN) often collide with moving obstacles while walking. Whether the collisions occur as a result of attentional-perceptual deficits caused by VSN or due to post-stroke locomotor deficits, is not understood. We assessed individuals with VSN on a seated, joystick-driven obstacle avoidance task, thus eliminating the influence of locomotion. Methods: Twelve participants with VSN were tested on obstacle detection and obstacle avoidance tasks in a virtual environment that included three obstacles approaching head-on or 30° contralesionally/ ipsilesionally. Results: Greater detection times were observed for contralesional or head-on obstacle approaches, while collisions were observed only for the contralesional and head-on obstacle approaches. For the contralesional obstacle approach, participants initiated their avoidance strategies at smaller distances from the obstacle and maintained smaller minimum distances from the obstacles. The distance at detection showed a negative association with the distance at the onset of avoidance strategy for all three obstacle approaches. Conclusion: The observation of collisions with contralesional and head-on obstacles, in the absence of locomotor burden, provides evidence that attentional-perceptual deficits due to VSN, independent of post-stroke locomotor deficits, alters obstacle avoidance abilities.
    IEEE Transactions on Neural Systems and Rehabilitation Engineering 03/2015; 23(2):179. DOI:10.1109/TNSRE.2014.2369812 · 2.82 Impact Factor
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    ABSTRACT: Dual-tasking that involves the performance of a cognitive task while walking can be challenging for post-stroke individuals. The presence of an attentional disorder such as visuospatial neglect (VSN) may further compromise the performance on the cognitive task, locomotor task or both. We observed the differences between participants with and without VSN on the ability to avoid moving obstacles while walking and performing a cognitive task. Methods: Three post-stroke participants- two with VSN (V1, V2) and one without VSN (S1) were assessed in a virtual environment consisting of a target and three obstacles located head-on (HO) and 30° contralesionally (CL) and ipsilesionally (IL). Participants were instructed to walk towards the target while avoiding the obstacle that randomly approached from one of the three directions. A simple pitch-identification task was used as a cognitive task. 3 tasks were performed a) a seated- cognitive task b) walking task alone and c) walking with cognitive task. We compared rates of cognitive error, the collision rates (CR), walking speeds and minimum distances from the obstacle between the cognitive alone /walking alone- single task (ST), and walking with cognitive task- dual task (DT) conditions. Results: No participant showed errors on the cognitive alone task. During the walking task, participant S1 showed collisions with HO obstacle during both the ST (CR= 40%) and DT condition (CR=40%) with no errors on the cognitive task. During the DT condition, however, participant S1 maintained larger minimum distances from obstacles as well as faster walking speeds for all three obstacle conditions, compared to the ST. Participant V1 showed no collisions during the ST but collided with CL (CR= 50%) and HO (CR= 20%) obstacles during the DT. Participant V2 showed collisions with CL obstacle during the ST and DT condition (CR=50%). Both V1 and V2 showed errors in the cognitive task during the DT condition for all three obstacle approaches (range= 20-100% of trials). V1 and V2 also maintained slower walking speeds and smaller minimum distances for all three obstacle approaches during the DT compared to the ST. Discussion: In the participant without VSN, addition of a simple dual task did not result in worsening of collision rates. Participants with VSN, however, demonstrated deterioration in cognitive or both locomotor & cognitive performance during the DT condition. These preliminary results suggest that the addition of a simple cognitive task may burden the attentional resources in VSN resulting in worsening of task performance. Deterioration in obstacle avoidance performance may compromise safety while walking in the presence of moving objects.
    Society for Neurosciences, 2014, Washington DC; 11/2014
  • Samir Sangani · Anouk Lamontagne · Joyce Fung
    fNIRS 2014, Montreal, Quebec, Canada; 10/2014
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    Myriam Villeneuve · Virginia Penhune · Anouk Lamontagne
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    ABSTRACT: Objective: Music-supported therapy was shown to induce improvements in motor skills in stroke survivors. Whether all stroke individuals respond similarly to the intervention and whether gains can be maintained over time remain unknown. We estimated the immediate and retention effects of a piano training program on upper extremity function in persons with chronic stroke. Methods: Thirteen stroke participants engaged in a 3-week piano training comprising supervised sessions (9 × 60 min) and home practice. Fine and gross manual dexterity, movement coordination, and functional use of the upper extremity were assessed at baseline, pre-intervention, post-intervention, and at a 3-week follow-up. Results: Significant improvements were observed for all outcomes at post-intervention and follow-up compared to pre-intervention scores. Larger magnitudes of change in manual dexterity and functional use of the upper extremity were associated with higher initial levels of motor recovery. Conclusion: Piano training can result in sustainable improvements in upper extremity function in chronic stroke survivors. Individuals with a higher initial level of motor recovery at baseline appear to benefit the most from this intervention.
    Frontiers in Human Neuroscience 08/2014; 8:662. DOI:10.3389/fnhum.2014.00662 · 2.90 Impact Factor
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    ABSTRACT: Nous présentons un projet stratégique multidisciplinaire et multisectoriel mené par le Centre de recherche interdisciplinaire en réadaptation (CRIR), en collaboration avec un centre commercial montréalais, des organismes communautaires et des partenaires de recherche et industriels locaux, nationaux et internationaux. Depuis 2011 ayant le Centre commercial comme laboratoire vivant, plus de 45 projets ont été amorcés pour : (1) identifier les obstacles et facilitateurs environnementaux, physiques et sociaux à la participation ; (2) développer des technologies et interventions pour optimiser la fonction physique et cognitive ; (3) implanter et évaluer l’impact des technologies et interventions in vivo. Deux ans plus tard, avec une approche recherche action participative (RAP) dans le cadre de la Classification International du Fonctionnement, du handicap et de la santé (CIF) de l’OMS, nous discutons des défis et entreprises futures. Les défis incluent la création et le maintien de partenariats, assurant une approche RAP pour engager plusieurs parties prenantes (ex. personnes avec incapacités, chercheurs, professionnels de la santé, membres de la communauté et parties prenantes du centre commercial) et évaluant l’impact global du projet. Les entreprises futures, qui incluent mettre en lien les résultats de recherche avec les recommandations pour les rénovations du centre commercial, sont aussi présentées.
    Alter - European Journal of Disability Research/Revue Européenne de Recherche sur le Handicap 08/2014; 8(4). DOI:10.1016/j.alter.2014.07.003
  • Samir Sangani · Anouk Lamontagne · Joyce Fung
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    ABSTRACT: Background: Light touch (haptic) cues have been shown to improve postural stability in healthy older adults and more recently during gait in post stroke individuals. Recent studies utilizing EEG demonstrate that both the motor cortex and the corticospinal tract contribute directly to muscle activation in lower limbs during steady-state treadmill walking. However, cortical hemodynamic activity associated with changes in locomotor function in response to light haptic touch while walking on a self-paced treadmill remains unclear. The primary objective of our study is to utilize near infrared spectroscopy (NIRS) to investigate and characterize cortical activity in terms of concentration of oxygenated hemoglobin (Oxy-Hb) in both the frontal and sensorimotor cortices as posture and gait control is enhanced by haptic touch during self-paced treadmill locomotion in post stroke participants and healthy subjects walking at matching slow speeds. Methods: We have recruited 7 healthy control subjects and 1 stroke participant, and will target testing 10 post-stroke and 10 control subjects in all. NIRS measurement was performed using the Hitachi ETG-4000 system with a custom-built optode cap covering the frontal and sensorimotor cortices. The experimental protocol included repeated block trials consisting of two alternating blocks of standing and walking at the comfortable self-selected speed in stroke participants and slow speed in healthy controls. There were a total of three trials, where the haptic touch condition was randomly alternated with no haptic touch condition. The cortical hemodynamic response was quantified in four different phases termed as preparation, acceleration, steady-state walk, and deceleration. Primary outcome measures included gait speed and changes in Oxy-Hb concentrations at those four phases with respect to quiet standing. Results: Light haptic touch during slow speed walking in healthy controls did not show any significant changes in gait speed as well as in cortical activity. In contrast, individuals with stroke had a significant increase in gait speed in the haptic touch condition compared to the no haptic touch condition. This increase was associated with an increase in the activation of the lateral sensorimotor cortex of the affected hemisphere (Figure 1). In addition, changes in laterality index with light haptic touch demonstrated improved cortical symmetry during walking. Conclusion: Improved symmetry of cortical activation of sensorimotor and frontal regions associated with enhanced locomotor ability post stroke provides preliminary evidence of promoting sensorimotor enhancement with haptic feedback during locomotion, as a novel intervention of gait rehabilitation post stroke.
    International Society of Posture and Gait Congress, Vancouver, British Columbia, Canada; 07/2014
  • Gayatri Aravind · Anouk Lamontagne
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    ABSTRACT: Post-stroke sensorimotor impairments can lead to altered ability to control locomotor heading and avoid obstacles while walking. The presence of visuospatial neglect (VSN) may further hamper the control of walking trajectories due to impairments in the uptake & utilisation of visual information from the contralesional side of space. We examined how participants with post-stroke VSN control their heading to avoid collisions in response to moving obstacles while walking in a virtual environment(VE). Methods: Twelve post-stroke VSN subjects were tested in a VE consisting of a target & 3 obstacles, one of which randomly approached from head-on or 30° to the contralesional/ipsilesional side including control trials with no obstacles. Participants walk towards the target while avoiding a collision with the obstacle..We examined the spatial relationships (heading, heading onsets) maintained by the participants in space and in relation to the obstacle and target. Results: The participants showed a preference to deviate towards the ipsilesional side (positive values) for all four obstacle conditions (from 9.0°±4.2 to 9.9°±5.9; mean±1SD). Subjects also showed preference to rotate their heads ipsilesionally for head-on(11.5°± 9.4), ipsilesional(6.4°±6.1) contralesional obstacle approaches(12.4°±6.6) and control trials(9.2°±6.1). The ipsilesional head rotation and deviation of trajectory continued to be observed even after the obstacle passed the subject. Five participants collided with the contralesional obstacle while eight collided with the head on obstacle. Contralesional colliders showed larger heading reorientations(12.2°±3.8) compared non-colliders(6.6°±4.1), whereas head-on colliders obstacles showed smaller heading reorientations (9.6°±6.9) compared to non-colliders (11.2°±5.7). The colliders also showed delayed onsets of heading reorientation compared to non-colliders for both contralesional (2.6 s±0.5 vs. 2.2 s±0.6) & head-on (4.7s±1.6 vs. 4.0±1.6) obstacles. Discussion: The persistence to veer and reorient the head towards the ipsilesional side is consistent with ipsilesional bias commonly observed in VSN[1] and contrast with the behaviour of healthy individuals reported in a previous study where deviation was observed to occur in the direction opposite to the obstacle approach[2]. The delayed initiation of heading reorientation observed in the colliders may have translated into reduced time and distance available to execute an avoidance strategy. Additionally, the smaller heading reorientation in colliders with head-on obstacles may have kept the participants in the path of collisions, while the larger heading reorientation observed in contralesional colliders may have been an attempt to compensate for the delay in onset of reorientation. Conclusion: Persons with post-stoke VSN collide with obstacles approaching from the contralesional side and from head-on. Control of heading could be a determinant in the risk of collision with moving obstacles.
    International Society of Posture and Gait Research, 2014 (ISPGR), Vancouver, Canada; 06/2014
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    ABSTRACT: Background: Spatial navigation in the presence of dynamic obstacles involves executing locomotor strategies to avoid collisions while navigating towards the goal. The dynamic interaction between a moving person and a moving obstacle can be expressed using the classical differential games approach, whereby subjects’ navigational strategies are shaped largely under the influence of the obstacle until the possibility of a collision is negated. Further, the choice of a circumvention strategy can depend on the degree of influence exerted by the obstacle. The objective of this work is to explore the effect of changing the strength of obstacle influence on navigational strategies used for obstacle avoidance. Methods: The differential games model was based upon an experimental set-up that involved subjects walking in a virtual environment towards a central blue target while avoiding obstacles that randomly approached the subjects from head-on or from 30° left and right. For this work, both subject and the obstacle are assumed to move in a 6mx6m space at a speed of 0.5 m/s. The obstacle influence was modelled by a Gaussian 2D distribution with constant amplitude and flexible elliptical horizontal cross-sections. The elliptical cross-section was oriented such that the longer diameter lay along the direction of obstacle motion. The effect of changing the ratio of longer to shorter diameters from 1.2/0.4 to 1.1/0.4 on obstacle circumvention behavior was simulated. Results: In the simulation, the movement of the subject was similar to the mechanical movement of a heavy ball in a gravitational field on an uneven surface. The subject chose the path with lowest resistance to avoid the obstacle and reach the target. The nature of the avoidance strategy was dependent upon the strength of obstacle influence which was in turn dependent on the size of its horizontal cross-section. With changes in the horizontal cross-section, circumvention behaviours also underwent consequent changes. A longer to shorter diameter ratio of 1.1/0.4 enabled the subject to avoid the obstacle by passing in front of it. A small increase in this ratio to 1.2/0.4 forced a change in the avoidance strategy with the subject now avoiding the obstacle by passing behind it. Thus a small change in the obstacle influence could affect substantial changes in the obstacle avoidance behaviours. Conclusions: In a mathematical simulation of obstacle avoidance based on differential games, a change in the strength of obstacle influence causes consequent changes in avoidance behaviors. The strength of this influence may be related to the characteristics of the obstacle (speed, direction of motion etc.) or the subject’s perception of their capabilities (ability to generate appropriate and sudden changes to gait speed or trajectory). This approach will be further used to formulate obstacle influence parameters using experimental data.
    International Society of Posture and Gait Research, Vancouver, BC, Canada; 06/2014
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    ABSTRACT: Through the lens of a Rehabilitation Living Lab, this paper presents what happens when researchers work with managers and users in the design situation of an urban commercial complex. This multi-sectorial and interdisciplinary research project brings together over 45 researchers to explore issues of social inclusion and social participation of people with disabilities, as they arrive and use the shopping complex. Within the context of a Living Lab, researchers implement various research projects from diverse research paradigms and methodological perspectives. While the research method for the overarching project is within the general framework of participatory action research, all researchers use clinical, basic and experimental forms of research (Friedman, 2003) to move forward the goals and research streams defined at the outset. The research is supported by a parallel design activity with students in a baccalaureate design studio. The overall research project goals and an example of a pilot project are presented in concert with a design studio activity, to consider potential concepts that are research-informed. Discussion of results reveals salient issues that emerge in early findings in pilot studies, and underscores what happens when people from diverse research perspectives work together.
    DRS 2014 International Conference of the Design Research Society, Umea, Sweden; 05/2014
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    Gayatri Aravind · Anouk Lamontagne
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    ABSTRACT: For safe ambulation in the community, detection and avoidance of static and moving obstacles is necessary. Such abilities may be compromised by the presence of visuospatial neglect (VSN), especially when the obstacles are present in the neglected, i.e. contralesional field. Twelve participants with VSN were tested in a virtual environment (VE) for their ability to a) detect moving obstacles (perceptuo-motor task) using a joystick with their non-paretic hand, and b) avoid collision (locomotor task) with moving obstacles while walking in the VE. The responses of the participants to obstacles approaching on the contralesional side and from head-on were compared to those during ipsilesional approaches. Up to 67 percent of participants (8 out of 12) collided with either contralesional or head-on obstacles or both. Delay in detection (perceptuo-motor task) and execution of avoidance strategies, and smaller distances from obstacles (locomotor task) were observed for colliders compared to non-colliders. Participants' performance on the locomotor task was not explained by clinical measures of VSN but slower walkers displayed fewer collisions. Persons with VSN are at the risk of colliding with dynamic obstacles approaching from the contralesional side and from head-on. Locomotor-specific assessments of navigational abilities are needed to appreciate the recovery achieved or challenges faced by persons with VSN.
    Journal of NeuroEngineering and Rehabilitation 03/2014; 11(1):38. DOI:10.1186/1743-0003-11-38 · 2.62 Impact Factor
  • G. Aravind · A. Lamontagne
    Canadian Stroke Congress; 12/2013
  • Samir Sangani · Anouk Lamontagne · Joyce Fung
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    ABSTRACT: Light touch (haptic) cues have been shown to improve postural stability in older adults and more recently during gait in people post stroke. The term haptic touch refers to a sense of touch, providing hand/fingers their inherent ability to explore, detect and perceive specific environmental features around them. As new evidence emerges from clinical studies, haptic touch shows great potential as an intervention to improve postural control and dynamic stability for stroke rehabilitation. Recent studies utilizing EEG demonstrate that the motor cortex and the corticospinal tract contribute directly to muscle activation in lower limbs observed during steady state treadmill walking. In addition, modulation of the cortical representation of fingertip afferent inputs has been shown to be associated with reduced postural sway during tandem standing. However, it is still unclear whether the application of haptic cues corresponds to plastic changes in the sensorimotor cortex that could translate into improved locomotor function with repetitive training. The primary objective of our study is to utilize near infrared spectroscopy (NIRS) to investigate and characterize cortical hemodynamic activity in terms of oxy-hemoglobin (Oxy-Hb) concentrations in both the frontal and sensorimotor cortices as posture and gait control is enhanced by haptic touch provided to the fingertip during self-paced treadmill locomotion at three different gait speeds (slow, comfortable, and as fast as possible). NIRS measurement was performed using the Hitachi ETG-4000 system with a custom-built optode cap covering the frontal and sensorimotor cortices. We have recruited 6 healthy control subjects and will target testing 10 post-stroke and 10 control subjects in all. Light haptic touch resulted in decrease in Oxy-Hb concentrations in the frontal cortices during the three speed conditions compared to trials without haptic touch. In addition, light haptic touch increased the gait speed of control participants during comfortable and fast speed walking conditions. We can thus investigate cortical mechanisms that produce different patterns of gait kinematics when participants walk at different self-selected speeds in the absence or presence of haptic feedback. A decreased asymmetric inter-hemispheric activation of the sensorimotor cortex associated with enhanced recovery of functional mobility would provide clinicians with strong evidence of utilizing haptic feedback as a novel intervention for stroke rehabilitation.
    Neuroscience 2013, San Diego, California, USA; 11/2013
  • Samir Sangani · Joyce Fung · Anouk Lamontagne
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    ABSTRACT: Background: Mobility problems among stroke survivors have a serious impact on their functional independence and quality of life. Over the last decade, researchers and clinicians have acknowledged the importance of incorporating intensive task-specific practice in gait retraining paradigms after stroke. Speed-intensive gait training has been shown to provide beneficial effects, both in terms of improved walking speeds as well as in the overall kinematics of hemiparetic gait. Recent studies utilizing EEG demonstrate that the motor cortex and the corticospinal tract contribute directly to muscle activation in lower limbs observed during steady-state treadmill walking. However, cortical mechanisms underlying the efficacy of incorporating different self-imposed speeds during self-paced treadmill locomotion remain unclear. Objective: To determine cortical mechanisms underlying the control of gait speed, near-infrared spectroscopy (NIRS) is used to investigate and characterize hemodynamic activity in terms of oxy-hemoglobin (Oxy-Hb) concentrations in both the frontal and sensorimotor cortices during self-paced treadmill locomotion at three different gait speeds (slow, comfortable, and as fast as possible). Methods: We have recruited 6 healthy control subjects and will target testing 10 post-stroke and 10 control subjects in all. NIRS measurement was performed using the Hitachi ETG-4000 system with a custom-built optode cap (44 channels) covering the frontal and sensorimotor cortices. A custom-built self-paced treadmill was utilized wherein the speed of the treadmill can be servo-controlled by the subject’s voluntary acceleration and deceleration via an eletropotentiometer and thus subjects had full control of their own walking speed. Results: Changes in concentrations of Oxy-Hb in the sensorimotor and frontal cortex demonstrated increased activation during different phases of fast and slow walking conditions as compared to walking at a comfortable speed. Conclusion: Minimal cortical activation is required to control steady-state walking at comfortable speed, but any deviation from the optimal speed requires conscious effort and hence increased cortical activation.
    4th Canadian Stroke Congress, Montreal, Quebec, Canada; 10/2013
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    Tal Krasovsky · Anouk Lamontagne · Anatol G Feldman · Mindy F Levin
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    ABSTRACT: Many falls in older adults occur during walking following trips. Following a trip, older adults take longer than younger adults to recover steady-state walking. Although faster gait speed may improve interlimb coordination, it may also increase fall risk in older adults. We hypothesized that older adults would take longer than younger adults to recover from an unexpected perturbation during gait especially when walking faster. Twelve younger (26.3±4.4 years) and 12 older adults (68.5±3.4 years) walked at comfortable, faster and slower speeds when movement of the dominant leg was unexpectedly arrested for 250ms at 20% swing length. Gait stability was evaluated using the short- and longer-term response to perturbation. In both groups, walking faster diminished the occurrence of elevation and increased that of leg lowering. Older adults took longer than younger adults to recover steady-state walking at all speeds (3.36±0.11 vs. 2.89±0.08 strides) but longer-term recovery of gait stability was not related to gait speed. Arm-leg and inter-arm coordination improved with increasing gait speed in both groups, but older adults had weaker inter-leg coupling following perturbation at all speeds. Although both younger and older adults used speed appropriate responses immediately following perturbation, longer duration of recovery of steady-state walking in older adults may increase fall risk in uncontrolled situations, regardless of gait speed. Recovery from perturbation when walking faster was associated with better interlimb coordination, but not with better gait stability. This indicates that interlimb coordination and gait stability may be distinct features of locomotion.
    Gait & posture 08/2013; 39(1). DOI:10.1016/j.gaitpost.2013.08.011 · 2.30 Impact Factor
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    IASDR 2013 International Conference Consilience and Innovation in Design, Tokyo, Japan; 08/2013
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    Ala' Sami Aburub · Anouk Lamontagne
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    ABSTRACT: Individuals who have sustained a stroke can manifest altered locomotor steering behaviors when exposed to optic flows expanding from different locations. Whether these alterations persist in the presence of a visible goal and whether they can be explained by the presence of a perceptuo-motor disorder remain unknown. The purpose of this study was to compare stroke participants and healthy participants on their ability to control heading while exposed to changing optic flows and target locations. Ten participants with stroke (55.6 +/- 9.3 yrs) and ten healthy controls (57.0 +/- 11.5 yrs) participated in a mouse-driven steering task (perceptuo-motor task) while seated and in a walking steering task. In the seated steering task, participants were instructed to head or 'walk' toward a target in the virtual environment by using a mouse while wearing a helmet-mounted display (HMD). In the walking task, participants performed a similar steering task in the same virtual environment while walking overground at their comfortable speed. For both experiments, the target and/or the focus of expansion (FOE) of the optic flow shifted to the side (+/-20[degree sign]) or remained centered. The main outcome measure was net heading errors (NHE). Secondary outcomes included mediolateral displacement, horizontal head orientation, and onsets of heading and head reorientation. In the walking steering task, the presence of FOE shifts modulated the extent and timing of mediolateral displacement and head rotation changes, as well as NHE magnitudes. Participants overshot and undershot their net heading, respectively, in response to ipsilateral and contralateral FOE and target shifts. Stroke participants made larger NHEs, especially when the FOE was shifted towards the non-paretic side. In the seated steering task, similar NHEs were observed between stroke and healthy participants. The findings highlight the fine coordination between rotational and translational steering mechanisms in presence of targets and FOE shifts. The altered performance of stroke participants in walking but not in the seated steering task suggests that an altered perceptuo-motor processing of optic flow is not a main contributing factor and that other stroke-related sensorimotor deficits are involved.
    Journal of NeuroEngineering and Rehabilitation 07/2013; 10(1):80. DOI:10.1186/1743-0003-10-80 · 2.62 Impact Factor

Publication Stats

1k Citations
142.95 Total Impact Points

Institutions

  • 2003–2015
    • McGill University
      • School of Physical and Occupational Therapy
      Montréal, Quebec, Canada
  • 1997–2002
    • Laval University
      • • Faculty of Medicine
      • • Département de Réadaptation
      Quebec City, Quebec, Canada
    • Institut de réadaptation en déficience physique de Québec
      Québec, Quebec, Canada