Anouk Lamontagne

McGill University, Montréal, Quebec, Canada

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Publications (47)89.06 Total impact

  • 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. · 2.57 Impact Factor
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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; · 2.58 Impact Factor
  • Source
    Ala S 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. · 2.57 Impact Factor
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    ABSTRACT: Individuals with stroke demonstrate deficits in community ambulation, which may be related to deficits in obstacle avoidance. We have devised a VR paradigm to assess locomotor strategies for obstacle circumvention. Four individuals with chronic stroke and four healthy controls walked towards a target while in the presence of a moving obstacle. Dynamic clearance from the obstacle was smaller among people with stroke for a head-on obstacle approach, while it was larger than the control group for diagonal obstacle approaches. This can be attributed to different locomotor adjustments required for each obstacle approach direction and perceptuo-motor impairments in people with stroke.
    Virtual Rehabilitation (ICVR), 2013 International Conference on; 01/2013
  • A. Liu, J. Fung, A. Lamontagne, R. Hoge, J. Doyon
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    ABSTRACT: Steering using optic flow allows adapting locomotion to the environment. Persons with brain lesions display difficulty steering and thus, gaining insight into the brain regions involved in steering may shed light on the disturbed mechanisms of visuomotor control. A joystick-based navigation task in a virtual environment was used to explore brain regions involved in steering control while exposed to optic flows of changing directions. Functional magnetic resonance imaging revealed that hMT+, bilateral cerebellum, frontal and supplementary eye fields are specifically involved in steering control and may reflect the pathway in which visual motion information is transformed into goal-directed action.
    Virtual Rehabilitation (ICVR), 2013 International Conference on; 01/2013
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    Myriam Villeneuve, Anouk Lamontagne
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    ABSTRACT: Music-supported therapy (MST) is an innovative approach that was shown to improve manual dexterity in acute stroke survivors. The feasibility of such intervention in chronic stroke survivors and its longer-term benefits, however, remain unknown. The objective of this pilot study was to estimate the short- and long-term effects of a 3-week piano training program on upper extremity function in persons with chronic stroke. A multiple pre-post sequential design was used, with measurements taken at baseline (week0, week3), prior to (week6) and after the intervention (week9), and at 3-week follow-up (week12). Three persons with stroke participated in the 3-week piano training program that combined structured piano lessons to home practice program. The songs, played on an electronic keyboard, involved all 5 digits of the affected hand and were displayed using a user-friendly MIDI program. After intervention, all the three participants showed improvements in their fine (nine hole peg test) and gross (box and block test) manual dexterity, as well as in the functional use of the upper extremity (Jebsen hand function test). Improvements were maintained at follow-up. These preliminary results support the feasibility of using an MST approach that combines structured lessons to home practice to improve upper extremity function in chronic stroke.
    Stroke research and treatment. 01/2013; 2013:159105.
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    ABSTRACT: BACKGROUND AND PURPOSE:: Decreased walking speed after stroke may be related to changes in temporal and distance gait factors, endurance, and balance. Functional gait deficits may also be related to changes in coordination, specifically between transverse (yaw) plane trunk movements. Our aim was to determine the relationship between intersegmental coordination during gait and functional gait and balance deficits in individuals with stroke. METHODS:: Eleven individuals with chronic stroke and 11 age-matched subjects without disability participated in 2 sessions. In Session 1, clinical evaluations of trunk/limb impairment (Chedoke-McMaster Stroke Assessment), functional gait (Functional Gait Assessment), and balance (BesTest) were performed. In Session 2, gait kinematics during eight 30-second walking trials on a self-paced treadmill at 2 speeds (comfortable and equivalent) were recorded. Equivalence of walking speeds was obtained by asking subjects without disability to walk approximately 20% slower and subjects with stroke to walk approximately 20% faster than their comfortable speed. Thorax and pelvis 3-dimensional angular ranges of motion (ROMs) and intersegmental coordination using the continuous relative phase were analyzed. RESULTS:: Comfortable walking speed was slower in subjects with stroke (0.78 m/s) than in subjects without disability (1.22 m/s), despite matched cadences. At both comfortable and equivalent walking speeds (0.97-0.98 m/s), participants with stroke used more thoracic ROM than pelvic transverse ROM in comparison with subjects without disability. Transverse thorax-pelvis coordination was similar between groups when walking speeds were equivalent, but there was more in-phase coordination in participants with stroke walking at their comfortable, slower speed. In subjects with stroke, thoracic ROM and continuous relative phase were correlated with several clinical functional gait and balance measures. DISCUSSION AND CONCLUSION:: Changes in segmental transverse ROM and coordination were associated with poor gait and with balance abilities in individuals with stroke. Interventions focusing on recovery of these movement characteristics may lead to better clinical outcomes.
    Journal of neurologic physical therapy: JNPT 10/2012; · 1.65 Impact Factor
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    ABSTRACT: Falls during walking are a major cause of injury in post-stroke individuals, and walking faster may further decrease gait stability. We compared gait stability between high-functioning post-stroke individuals and controls at matched speeds. We also evaluated the effect of a speed increase on gait stability in post-stroke individuals. Ten stroke subjects and 10 age-matched controls walked on a self-paced treadmill at matched speeds. Stroke subjects also walked 20% faster than comfortable. Movement of the non-paretic (stroke) or dominant leg (controls) was arrested unexpectedly at 20% of swing. Stroke subjects typically lowered the perturbed leg following perturbation (58% of cases) while controls maintained the leg in the air (49% of cases; p<0.01). In post-stroke subjects, double-support duration was restored later than in controls (4.6±0.8 versus 3.2±0.3 strides; p<0.007). Stroke subjects had larger long-term phase shifts of arm and leg movements, which were less coordinated on the paretic side. A moderate speed increase (~20%) did not influence gait stability or interlimb coupling. However, clinical impairment was related to recovery from perturbation at faster speed. Faster walkers among stroke subjects had better non-paretic arm-leg coupling but were not more stable. Our results suggest that long-term phase resetting of gait involves a high level of motor control that regulates translation of the body in the environment. Impaired descending control following a brain lesion decreases the ability of the motor system to recover from perturbations and to regulate interlimb phase relationships. However, interlimb coordination may not be a major factor in recovery from gait perturbation.
    Journal of Neurophysiology 10/2012; · 3.30 Impact Factor
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    ABSTRACT: Most falls in older adults occur when walking, specifically following a trip. This study investigated the short- and longer term responses of young (n = 24, 27.6 ± 4.5 yr) and older adults (n = 18, 69.1 ± 4.2 yr) to a trip during gait at comfortable speed and the role of interlimb coordination in recovery from tripping. Subjects walked on a self-paced treadmill when forward movement of their dominant leg was unexpectedly arrested for 250 ms. Recovery of center of mass (COM) movements and of double-support duration following perturbation was determined. In addition, the disruption and recovery of interlimb coordination of the arms and legs was evaluated. Although young and older subjects used similar lower limb strategies in response to the trip, older adults had less stable COM movement patterns before perturbation, had longer transient destabilization (>25%) after perturbation, required more gait cycles to recover double-support duration (older, 3.48 ± 0.7 cycles; young, 2.88 ± 0.4 cycles), and had larger phase shifts that persisted after perturbation (older, -83° to -90°; young, -39° to -42°). Older adults also had larger disruptions to interlimb coordination of the arms and legs. The timing of the initial disruption in coordination was correlated with the disturbance in gait stability only in young adults. In older adults, greater initial COM instability was related to greater longer term arm incoordination. These results suggest a relationship between interlimb coordination and gait stability, which may be associated with fall risk in older adults. Reduced coordination and gait stability suggest a need for stability-related functional training even in high-functioning older adults.
    Journal of Neurophysiology 02/2012; 107(9):2560-9. · 3.30 Impact Factor
  • Jessica Berard, Joyce Fung, Anouk Lamontagne
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    ABSTRACT: The purpose of this study was to investigate the ability of young and old subjects to reweight visual cues while walking at normal and fast speeds. Ten young (23.49 ± 4.72) and ten older adults (age 76.22 ± 3.11) were asked to physically walk straight while viewing a virtual scene in a head-mounted display (HMD) unit under three conditions: no visual perturbation, blank (no visual input), and visual perturbation. Subjects performed the tasks walking at two speeds: preferred self-pace and fast. Variables calculated included trajectory, heading angle, and body segment orientations. In the perturbation condition, the older adults walked with higher segmentation and more deviations of the body's centre of mass. Only the young subjects were affected by the walking speed, with an improved performance when walking fast. Old age affects the ability to re-weight visual information and make postural or locomotor adjustments in real time. The lower errors of the young adults in the fast conditions suggest decreased cortical control of locomotion with increasing speeds. Visual information presented in real time can impact on balance and mobility in older adults, and thus should be given serious consideration for the purpose of evaluation and intervention.
    Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 12/2011; 123(7):1422-8. · 3.12 Impact Factor
  • Jessica Berard, Joyce Fung, Anouk Lamontagne
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    ABSTRACT: Persons with a chronic stroke often manifest mobility deficits that may in part be related to altered visuomotor control. Specifically, the ability to use optic flow, which reflects self-motion, may be compromised after a stroke. We evaluated the locomotor behavior of 6 subjects with chronic stroke as they walked overground while viewing a virtual room displayed in a head-mounted display. The subjects were asked to walk straight in the virtual environment (VE). At 1.5m of forward walking, the room was slowly rotated up to 40° towards the paretic or non-paretic side, or remained centered (0°). In order to maintain a straight trajectory or a small net heading error in the VE, subjects could rotate their head, with or without modifying their walking trajectory. The responses of subjects were varied in terms of strategies and accuracy, leading to a wide range of net heading errors, in the VE. While there was no precise biomarker of excellent performance, the two individuals with the poorest performance had a history of visuospatial neglect. walking, steering, vision, stroke, hemiparetic, gait, visual motion, neglect
    Virtual Rehabilitation (ICVR), 2011 International Conference on; 07/2011
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    ABSTRACT: The ability to accurately judge distance and time to collision is an important perceptual determinant in shaping obstacle circumvention strategies for functional locomotion. In addition, deficits in planning and execution, as well as biomechanical constraints imposed by age or neurological insult may lead to avoidance failure in this population. We have designed a closed system in sitting displaying self motion through a virtual environment to evaluate perceptual and navigational strategies for obstacle circumvention. In a pilot study involving six healthy young subjects and one older participant, all subjects perceived collision with a moving obstacle to have occurred almost a meter before the actual collision would have taken place. The older participant consistently under-estimated the distance of collision to a larger extent as compared to the young subjects. In the navigation task using a joystick, the older individual initiated medio-lateral deviations later than the younger individuals. The clearance distance was also observed to be smaller for the older participant thus increasing the risk of collision. Deficits in depth perception as well as motor planning may contribute to increased errors. However, rehabilitation interventions that use VR can be utilized to improve perceptual and planning abilities, such that efficacious avoidance strategies can be facilitated. Moreover, further testing of locomotion in environments may help devise novel interventions for promoting ambulation.
    Virtual Rehabilitation (ICVR), 2011 International Conference on; 07/2011
  • Jessica R Berard, Joyce Fung, Anouk Lamontagne
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    ABSTRACT: Optic flow is a powerful visual cue for the control of locomotion. Considerable research has focused on how healthy young people use and perceive optic flow. However, little is known on how older adults use this type of visual motion to control walking. The purpose of this study is to investigate the ability of young and older adults to adjust their physical walking trajectory in response to a rotation of the optic flow presented in a virtual environment. Ten healthy young adults (mean age 23.49 ± 4.72 yr) and 10 healthy older adults (mean age 76.22 ± 3.11 yr) participated in the study. Subjects were instructed to walk straight in a virtual environment viewed within a head-mounted display unit as they walked overground for 5 m, while the focus of expansion was gradually rotated to the left or the right by 40°. All subjects responded with a similar strategy by rotating their head and body in the direction away from the orientation of the perturbation. The younger subjects achieved almost complete corrections and had very small net heading errors. In contrast, the older adults had delayed and smaller reorientations, particularly in the head, thus showing significantly larger heading errors compared with younger subjects. We conclude that older adults retain the ability to use optic flow to control their walking trajectory, although smaller, delayed head rotations and larger heading errors may indicate an age-dependent effect on sensorimotor coordination.
    Journal of Neurophysiology 06/2011; 106(3):1089-96. · 3.30 Impact Factor
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    ABSTRACT: Locomotion is presumably guided by feed-forward shifts in the referent body location in the desired direction in the environment. We propose that the difference between the actual and the referent body locations is transmitted to neurons that virtually diminish this difference by appropriately changing the referent body configuration, i.e. the body posture at which muscles reach their recruitment thresholds. Muscles are activated depending on the gap between the actual and the referent body configurations resulting in a step being made to minimize this gap. This hypothesis implies that the actual and the referent leg configurations can match each other at certain phases of the gait cycle, resulting in minimization of leg muscle activity. We found several leg configurations at which EMG minima occurred, both during forward and backward gait. It was also found that the set of limb configurations associated with EMG minima can be changed by modifying the pattern of forward and backward gait. Our hypothesis predicts that, in response to perturbations of gait, the rate of shifts in the referent body location can temporarily be changed to avoid falling. The rate influences the phase of rhythmic limb movements during gait. Therefore, following the change in the rate of the referent body location, the whole gait pattern, for all four limbs, will irreversibly be shifted in time (long-lasting and global phase resetting) with only transient changes in the gait speed, swing and stance timing and cycle duration. Aside from transient changes in the duration of the swing and/or stance phase in response to perturbation, few previous studies have documented long-lasting and global phase resetting of human gait in response to perturbation. Such resetting was a robust finding in our study. By confirming the notion that feed-forward changes in the referent body location and configuration underlie human locomotion, this study solves the classical problem in the relationship between stability of posture and gait and advances the understanding of how human locomotion involves the whole body and is accomplished in a spatial frame of reference associated with the environment.
    Experimental Brain Research 03/2011; 210(1):91-115. · 2.22 Impact Factor
  • Andrei Garcia Popov, Anouk Lamontagne
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    ABSTRACT: The ability of healthy young individuals to accurately steer toward a virtual target while experiencing different foci of expansion (FOE) and target positions was examined with the use of a virtual reality task. Ten participants steered toward the virtual target with the use of mouse displacements while sitting or while changing their body orientation during over-ground walking. Net virtual errors showed that participants were able to accurately align themselves with the target despite having confounding visual information regarding FOE location and heading direction. Participants performed better in the mouse-driven task than the walking task. This may be attributed to the nature of the tasks that employ different degrees of freedom. Altogether, results support the use of this virtual reality-based paradigm to further investigate the contribution of altered visual self-motion processing and gait-related impairments on steering abilities in stroke and in the elderly.
    01/2011;
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    ABSTRACT: Stroke patients manifest steering difficulties during walking, which may arise from an altered perception of visual motion. To examine the ability of stroke patients to control their heading direction while walking in a virtual environment (VE) describing translational optic flows (OFs) expanding from different directions. The authors evaluated 10 stroke patients and 11 healthy people while they were walking overground and visualizing a VE in a helmet-mounted display. Participants were instructed to walk straight in the VE and were randomly exposed to an OF having a focus of expansion (FOE) located in 5 possible locations (0 degrees, +/-20 degrees, and +/-40 degrees to the right or left). The body's center of mass (CoM) trajectory, heading direction, and horizontal body reorientation were recorded with a Vicon-512 system. Healthy participants veered opposite to the FOE location in the physical world, with larger deviations occurring at the most eccentric FOE locations. Stroke patients displayed altered steering behaviors characterized either by an absence of CoM trajectory corrections, multiple errors in the heading direction, or systematic veering to the nonparetic side. Both groups displayed relatively small CoM trajectory corrections that led to large virtual heading errors. The control of heading of locomotion in response to different OF directions is affected by stroke. An altered perception of heading direction and/or a poor integration of sensory and motor information are likely causes. This altered response to OF direction while walking may contribute to steering difficulties after stroke.
    Neurorehabilitation and neural repair 06/2010; 24(5):457-68. · 4.28 Impact Factor
  • Parkinsonism & Related Disorders - PARKINSONISM RELAT DISORD. 01/2010; 16.
  • Anouk Lamontagne, Joyce Fung, Jessica Berard
    Archives of Physical Medicine and Rehabilitation - ARCH PHYS MED REHABIL. 01/2010; 91(10).
  • Archives of Physical Medicine and Rehabilitation - ARCH PHYS MED REHABIL. 01/2010; 91(10).
  • Source
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    ABSTRACT: The purpose of this study was to examine the influence of arm movements on lower limb movement and muscle activation during treadmill walking after a stroke. Ten high functioning stroke and 10 healthy subjects walked on a treadmill while swinging their arms naturally, and while holding onto handles that were either fixed in place or allowed to slide along horizontal handrails. Full-body kinematics were recorded, along with bilateral surface electromyography from lower limb muscles. Arm movements influenced lower limb muscle activity but had little effect on movement patterns at the joints. When handrails were present a small amount of weight was borne through the upper limbs, and for stroke subjects this was reduced when the handles were free to slide. Activity of proximal leg muscles during stance was affected by the weight borne through the upper limbs, increasing when arm movements were performed. Soleus activity during stance was greatest with unsupported arm movements. In stroke subjects, early stance tibialis anterior activity in the paretic leg was greatest with no arm movements, and early swing tibialis anterior activity in both legs was greatest with unsupported arm movements. Many of the changes in muscle activation appeared to be due to changes in postural stability that occurred when performing arm movements. Overall, results support further study of the long-term changes associated with the inclusion of arm movements in gait rehabilitation protocols.
    Gait & posture 10/2009; 31(1):109-15. · 2.58 Impact Factor

Publication Stats

513 Citations
89.06 Total Impact Points

Institutions

  • 2001–2013
    • McGill University
      • School of Physical and Occupational Therapy
      Montréal, Quebec, Canada
  • 2011
    • Université de Montréal
      • Department of Physiology
      Montréal, Quebec, Canada
  • 1997–2002
    • Laval University
      • • Faculté de Médecine
      • • Département de Réadaptation
      Québec, Quebec, Canada
    • Institut de réadaptation en déficience physique de Québec
      Québec, Quebec, Canada