Normand Teasdale

The weighting of the sensory inputs is not uniform during movement preparation and execution. For instance, a transient increase in the transmission to the cortical level of cutaneous input ~700 ms was observed before participants initiated a step forward. The sensory facilitation occurred at a time when feet cutaneous information is critical for s...

Somatosensory inputs to the cortex undergo an early and a later stage of processing which are characterized by an early and a late somatosensory evoked potentials (SEP). The early response is highly representative of the stimulus characteristics whereas the late response reflects a more integrative, task specific, stage of sensory processing. We hy...

Reaching and grasping movements have been studied mostly in seated contexts. There are several tasks, however, that also impose specific postural constraints that may a€ect the organization of these movements. For example, in rock climbing, a successful grasp is con- ditional of an accurate static and dynamic postural control. The purpose of our stu...

Humans are capable of pointing to a target with accuracy. However, when vision is distorted through a visual rotation or mirror-reversed vision, the performance is initially degraded and thereafter improves with practice. There are suggestions this gradual improvement results from a sensorimotor recalibration involving an initial gating of the soma...

Background Traumatic brain injury (TBI) causes functional deficits that may significantly interfere with numerous activities of daily living such as driving. We report the case of a 20-year-old woman having lost her driver’s license after sustaining a moderate TBI. Objective We aimed to evaluate the effectiveness of an in-simulator training progra...

Achilles tendon vibration generates proprioceptive information that is incongruent with the actual body position; it alters the perception of body orientation leading to a vibration-induced postural response. When a person is standing freely, vibration of the Achilles tendon shifts the internal representation of the verticality backward thus the vi...

The driving performance of individuals with mild cognitive impairment (MCI) is suboptimal when compared to healthy older adults. It is expected that the driving will worsen with the progression of the cognitive decline and thus, whether or not these individuals should continue to drive is a matter of debate. The aim of the study was to provide supp...

Vibrating ankle muscles in freely standing persons elicits a spatially oriented postural response. For instance, vibrating the Achilles tendons induces a backward displacement of the body while vibrating the tibialis anterior muscle tendons induces a forward displacement. These displacements have been called vibration induced falling (VIF) response...

Humans are capable of pointing to a target with accuracy. However, when vision is distorted through a visual rotation or mirror-reversed vision, the performance is initially degraded and thereafter improves with practice. There are suggestions this gradual improvement results from a sensorimotor recalibration involving initial gating of the somatos...

Introduction: The prevalence of falls, fall-related injuries, and obesity has increased over the last decade. The objectives of this study were to investigate sex-specific association and dose-response relationship between BMI and falls (and related injuries) among community-dwelling elderly. Methods: Our study sample consisted of 15,860 adults...

Background: Due to the heterogeneity of the lesion following a traumatic brain injury (TBI) and the complexity of the driving task, driving assessment and rehabilitation in TBI individuals is challenging. Conventional driving assessment (on-road and in-clinic evaluations) has failed demonstrating effectiveness to assess fitness to drive in TBI ind...

Previous studies on the control of human balance suggested that increased pressure under the feet, leading to reduced plantar sole mechanoreceptors sensitivity, increases body sway. Although this suggestion is attracting, it is unclear whether increased plantar sole pressure simply reduces the transmission of plantar sole afferent to the cortex or...

Plusieurs etudes suggerent que le vieillissement normal pourrait affecter la conduite automobile, particulierement lors de la negociation d’intersections. Le but de cette etude naturalistique etait de documenter les comportements aux intersections marquees par un panneau d’arret obligatoire et de controle de la vitesse chez des personnes âgees de 6...

Wrist movement-related injuries account for a large number of repetitive motion injuries. Remarkably little, if any, empirical data exist to quantify the impact of neuromuscular disorders affecting the wrist or to validate the effectiveness of rehabilitation training programs on wrist functions. The aim of this project was to develop a biomechanica...

Introduction: L’inclusion d’exercices proprioceptifs dans les programmes de rééducation des entorses latérales de cheville repose sur une idée simple émise par Freeman dès 1965. Il est supposé que la déstabilisation du support augmente l’utilisation des signaux afférents musculaires en provenance de la cheville offrant une in fine meilleure stabili...

It is acknowledged that various factors impaired balance control. Among them, heavy body weight is associated with poor balance control because the location of the center of mass is further away from the ankle joint. Thus, a larger active ankle torque is required to counter the greater gravitational torque. Because balance motor commands have signa...

Une analyse biomécanique des modes opératoires réalisés lors de transferts de caisses d'un convoyeur à un diable (et vice versa) a été effectuée auprès de 17 manutentionnaires obèses et 20 manutentionnaires avec un poids santé. Les résultats montrent que l'anthropométrie des manutentionnaires obèses explique en grande partie un chargement lombaire...

Objective: The purpose of this study was to test the effect of various unstable support surfaces on the relevance of muscular proprioceptive signals originating from the ankle joint. Design: Ten healthy subjects were instructed to stand as still as possible on a force plate during 40 secs on three different surfaces: (1) stable, (2) unstable-uns...

We present a robust and accurate technique for the cross-calibration of 3D remote gaze trackers with stereoscopic scene vision systems between which no common imaging area exists. We empirically demonstrate that a multi-depth calibration approach yields remarkably superior results for obtaining 3D Point-of-Gaze (PoG) when compared with traditional...

There is a large proportion of individuals experiencing simulator sickness symptoms (headaches, nausea, paleness, etc.). Previous studies have reported that driving in a simulator, compared to on-road driving, can alter braking responses while stopping at intersections. Here we evaluated whether altered braking responses observed in fixed-base simu...

Obesity is an emerging problem that seems to be a risk factor in occupational health and safety. Musculoskeletal injuries are more frequent, and their indirect (non-medical) costs higher, in obese individuals than in workers having a healthy weight. Given that the obesity rate among Canadian workers is steadily rising, it is important to look at th...

When tracing a template with mirror-reversed vision (or distorted vision), the sensory information arising from the movement does not match the expected sensory consequences. In such situations, participants have to learn a new visuomotor mapping in order to trace the template with an accuracy and speed approaching that observed when tracing with d...

Several studies suggest that normal ageing could affect the driving behavior, particularly when negotiating intersections. The purpose of the current naturalistic study was to document the behavior of drivers aged 65 and over at stop-controlled intersections and describe the way they deal with speed limits. Twenty participants were recruited for a...

The countermovement jump test is often adopted to monitor lower-limb power of an individual. Despite several studies on the validity of this test, there is still a need to determine the minimal difference needed to be confident that a difference in power between two individuals is present or that a true change in the performance of an individual ha...

The objective of this study was to evaluate the work strategies of obese and healthy-weight workers in manual materials handling. Seventeen obese and 20 healthy-weight manual materials handlers participated in this laboratory study. The tasks consisted of transferring four boxes between a hand trolley and a conveyor. The weight of the box (15 vs. 2...

Epidemic excess of weight is considered as a critical and common health problem. It is associated with many physiological and psychological disorders. Other than metabolic problems, obesity also affects the efficient execution of daily living activities such as the simple act of standing, walking or grabbing an object while standing. This article a...

L’obésité est un problème émergent qui semble s’immiscer dans les problématiques de santé et de sécurité du travail. La prévalence de blessures musculo-squelettiques chez les individus obèses et les coûts indirects (non médicaux) sont plus élevés que ceux des travailleurs ayant un poids santé. Sachant qu’une hausse soutenue du taux d’obésité chez l...

The aim of this study was to examine the acute effects of mental work and moderate-intensity physical activity on various components of energy balance in young and healthy adults. With the use of a randomized crossover design, 35 participants aged 24 ± 3 years completed three 45-min conditions, namely, (i) resting in a sitting position (control), (...

Mental Work (MW) stimulates Cardiovascular (CV) functions in healthy adults and a reduction in cardiac parasympathetic modulation could be one mechanism involved in such a response. The influence of sex on these CV responses remains ambiguous. The aim of the study was to evaluate CV impacts of MW in healthy individuals and whether sex influences CV...

Purpose: Obesity is recognized as an important issue that has an impact on several areas of our daily lives, such as driving. In the literature there exists an association between obesity and motor vehicle crashes. The goal of this paper is to promote insightful reflection and discussion around this emerging topic. Methods: Searches were conducted...

The parameters dictating the temporal hand-head coordination during visually corrected movements remain elusive. Here we examine the effects of the nature (discrete vs reciprocal) and the difficulty (ID of 4.7, 5.7 and 6.7 bits) of the task on the temporal hand-head coordination during a Fitts' like paradigm. Subjects aimed at a single target (disc...

Driving retraining classes may offer an opportunity to attenuate some effects of aging that may alter driving skills. Unfortunately, there is evidence that classroom programs (driving refresher courses) do not improve the driving performance of older drivers. The aim of the current study was to evaluate if simulator training sessions with video-bas...

Older individuals have impaired balance control, particularly those that are frail and/or have sensory deprivations. Obese individuals show faster body sway during upright stance than normal weight individuals, suggesting that they also have difficulty controlling balance even if they do not have the same sensory issues as the older people. Therefo...

Obesity affects postural sway during normal quiet standing; however, the reasons for the increased postural sway are unknown. Improving muscular strength is regarded as a potential way to improve postural control, particularly for obese and overweight subjects. The purpose of this investigation is to evaluate the role of muscular strength on postur...

This study reports the case of a 23-year-old woman (MC) who sustained a severe traumatic brain injury in 2004. After her accident, her driving license was revoked. Despite recovering normal neuropsychological functions in the following years, MC was unable to renew her license, failing four on-road evaluations assessing her fitness to drive. In hop...

The aim of this study was to examine lane change strategies in active younger and older drivers. Visual inspection of mirrors and the blind spot and the control of the vehicle were documented in a simulator environment. Younger (n = 10, 21-31 years) and older (n = 11, 65-75 years) active drivers drove through a continuous simulated environment incl...

Rapid discrete goal-directed movements are characterized by a well known coordination pattern between the gaze and the hand displacements. The gaze always starts prior to the hand movement and reaches the target before hand velocity peak. Surprisingly, the effect of the target size on the temporal gaze-hand coordination has not been directly invest...

In this paper, we introduce a computer vision system specially designed for the analysis and interpretation of the cephalo-ocular behavior of drivers. The system is composed of both hardware and software components and is described in three steps. The first step is devoted to the description of the driving simulator and the developed software. The...

The aging of the population, combined with the overrepresentation of older drivers in car crashes, has engendered a whole body of research destined at finding simple and efficient assessment methods of driving capacities. Such a search is destined to fail, given that car crashes and unsafe driving behaviors can result from myriad interacting factor...

In this paper we introduce a new computer vision framework for the analysis and interpretation of the cephalo-ocular behavior of drivers. We start by detecting the most important facial features, namely the nose tip and the eyes. For that, we introduce a new algorithm for eyes detection and we call upon the cascade of boosted classifiers technique...

Overweight individuals sway more than normal weight individuals. Major weight loss improves their balance control despite a related decrease in muscle strength. Presumably, muscular strength is an important factor for balance control. This study investigated the effect that a change in body mass has on relative strength and balance control. Force (...

The aim of this study was to test the hypothesis that imbalance in patients with a severe deformity of the spine is associated with an increase in the sensory integration disorder. This paper is a case comparison study. Patients were divided into three groups: able-bodied (n = 53), observation (n = 23), and pre-brace (n = 26) groups. Time domain pa...

Adolescent idiopathic scoliosis is characterized by a three-dimensional deviation of the vertebral column and its etiopathogenesis is unknown. Various factors cause idiopathic scoliosis, and among these a prominent role has been attributed to the vestibular system. While the deficits in sensorimotor transformations have been documented in idiopathi...

Driving errors for older drivers may result from a higher momentary mental workload resulting from complex driving situations, such as intersections. The present study examined if the mental workload of young and older active drivers vary with the difficulty of the driving context. We adopted the probe reaction time (RT) technique to measure the wo...

This paper describes current research combining computer vision, virtual reality and kinesiology for analyzing the cephalo-ocular behavior of drivers in realistic driving contexts. The different components of the system are described and results are provided for each one. The ultimate goal of the system is to achieve automatic analysis of drivers’...

This study examines how older drivers responded to repeated exposures to a driver simulator. Older active and fit drivers participated in 5 simulator sessions within a 14-day period. For each session, simulator sickness symptoms were measured with the Simulator Sickness Questionnaire at baseline and post-session. In addition, participants completed...

The objective of this study was to determine which type of repetitive muscle contractions induces a greater acute impairment of elbow position sense. Eleven male subjects participating in the study underwent (i) an exercise task (ET) consisting of 9 sets of 10 voluntary isometric, concentric, or eccentric contractions randomly performed on three se...

To further document the impact of knowledge-based work (KBW) on spontaneous energy intake and glucose homeostasis. We used a within-subjects experimental design, in which each participant was engaged in each of the three 45-minute conditions followed by an ad libitum buffet, 1) resting in a sitting position; 2) reading a document and writing a summ...

We examined if a weight loss program improves the speed-accuracy tradeoff of goal-directed aiming movements of obese individuals. Ten obese subjects aimed at targets of different sizes from a seated and a standing posture. The kinematics of the aiming was recorded. All participants were evaluated before and after a weight loss program when weight r...

Stepping over an obstacle is preceded by a center of pressure (CoP) shift, termed anticipatory postural adjustments (APAs). It provides an acceleration of the center of mass forward and laterally prior to step initiation. The APAs are characterized in the lateral direction by a force exerted by the moving leg onto the ground, followed by an unloadi...

Decrease in fat mass and fat-free mass have been observed with weight loss induced by a dietary intervention or surgery. There are concerns that fat-free mass decrease could have some negative functional consequences. The aim of this study was to examine how weight loss affects strength and force control in obese and morbidly obese men. Weight loss...