Structural Learning Benefits in a Visuomotor Adaptation Task Generalize to a Contralateral Effector.

Structural learning is characterized by facilitated adaptation following training on a set of sensory perturbations all belonging to the same structure (e.g., 'visuomotor rotations').

Interdependence of movement amplitude and tempo during self-paced finger tapping: evaluation of a preferred velocity hypothesis.

This study examined the relation between movement amplitude and tempo during self-paced rhythmic finger tapping to test a preferred velocity account of the preferred tempo construct. Preferred tempo refers to the concept that individuals have preferences for the pace of actions or events in their environment (e.g.

Facilitated adaptation via structural learning increases bimanual interference.

Bimanual coordination is an essential feature of the motor system, yet interactions between the limbs during independent control remain poorly understood. Interference between the two hands, or the assimilation of movement characteristics between the two effectors, can be induced by perturbing one arm (e.g.

Bimanual Interference Increases with Force Demands and is Facilitated by Visuomotor Adaptation.

When simultaneously performing asymmetrical movements with both hands, there is a tendency for the action of one limb to interfere with control of the other. Little is known about how sensory feedback influences interference. We conducted two experiments to determine how manipulating force feedback and visual feedback alter bimanual coordination during center-out reaching.

Monkey see, monkey tap: mimicry of movement dynamics during coordinated tapping.

Common social behaviors, such as having a conversation, dancing, or playing a team sport, require precise interpersonal coordination of action. One question that emerges in research on interpersonal coordination is to what extent individuals implicitly mimic the spatial characteristics of movements for tasks that emphasize movement timing. To investigate this question, we conducted two experiments using an interpersonal synchronization-continuation tapping paradigm in which pairs of individuals tapped with their index finger on a table in synchrony with an auditory metronome and then continued tapping at the same tempo when the metronome stopped.

Controlling a robotic arm for functional tasks using a wireless head-joystick: A case study of a child with congenital absence of upper and lower limbs.

Children with movement impairments needing assistive devices for activities of daily living often require novel methods for controlling these devices. Body-machine interfaces, which rely on body movements, are particularly well-suited for children as they are non-invasive and have high signal-to-noise ratios. Here, we examined the use of a head-joystick to enable a child with congenital absence of all four limbs to control a seven degree-of-freedom robotic arm.

Neurophysiological Correlates of Adaptation and Interference during Asymmetrical Bimanual Movements.

In this study, we investigated brain dynamics during interference between hands during bimanual movements. Participants performed a bimanual center-out reaching task in which a visuomotor rotation was applied to the right hand while the left hand did not receive visual feedback of its movements. This manipulation resulted in interference from the adapting right hand to the kinesthetically guided left hand.

Age-dependent differences in learning to control a robot arm using a body-machine interface.

Body-machine interfaces, i.e. interfaces that rely on body movements to control external assistive devices, have been proposed as a safe and robust means of achieving movement and mobility; however, how children learn these novel interfaces is poorly understood.

Control of Integrated Task Sequences Shapes Components of Reaching.

Reaching toward an object usually consists of a sequence of elemental actions. Using a reaching task sequence, the authors investigated how task elements of that sequence affected feedforward and feedback components of the reaching phase of the movement. Nine right-handed adults performed, with their dominant and nondominant hands, 4 tasks of different complexities: a simple reaching task; a reach-to-grasp task; a reach-to-grasp and lift object task; and a reach-to-grasp, lift, and place object task.

Body-machine interface for control of a screen cursor for a child with congenital absence of upper and lower limbs: a case report.

Background: There has been a recent interest in the development of body-machine interfaces which allow individuals with motor impairments to control assistive devices using body movements.

Methods: In this case study, we report findings in the context of the development of such an interface for a 10-year old child with congenital absence of upper and lower limbs. The interface consisted of 4 wireless inertial measurement units (IMUs), which we used to map movements of the upper body to the position of a cursor on a screen.

Asymmetric interference in left-handers during bimanual movements reflects switch in lateralized control characteristics.

Interactions between the hands are a collateral of simultaneous bimanual movements and can inform us about the functional asymmetries of the dominant and nondominant hemisphere-effector systems. Few studies on bimanual coordination have focused on discrete movement control, and even fewer have looked at this in the context of handedness. Using a novel bimanual paradigm in which both hands perform simultaneous target-directed movements, this study addressed interference between the hands in two groups of left-handed individuals.

Development of kinesthetic-motor and auditory-motor representations in school-aged children.

In two experiments using a center-out task, we investigated kinesthetic-motor and auditory-motor integrations in 5- to 12-year-old children and young adults. In experiment 1, participants moved a pen on a digitizing tablet from a starting position to one of three targets (visuo-motor condition), and then to one of four targets without visual feedback of the movement. In both conditions, we found that with increasing age, the children moved faster and straighter, and became less variable in their feedforward control.

Crossmodal interference in bimanual movements: effects of abrupt visuo-motor perturbation of one hand on the other.

Studies on bimanual control inevitably deal with questions about interactions between the two effectors, mostly under conditions of sensory feedback of the same modality-usually vision-for both hands. This study used a novel paradigm in which one hand performed target-directed movements under visual control, while the other hand operated under predominantly kinesthetic control, without visual feedback. By introducing an abrupt visual feedback perturbation in the 'visible' hand, resulting in an update of its visuo-motor map, the robustness of the kinesthetic-motor map of the 'invisible' hand against interference from the visually controlled hand could be tested.

Control of discrete bimanual movements: how each hand benefits from the other.

Lateralized sensorimotor hand functions are often investigated separately or sequentially for each hand, e.g., in matching tasks, but rarely under more ecological circumstances where both hands move simultaneously.

Development of interactions between sensorimotor representations in school-aged children.

Reliable sensory-motor integration is a pre-requisite for optimal movement control; the functionality of this integration changes during development. Previous research has shown that motor performance of school-age children is characterized by higher variability, particularly under conditions where vision is not available, and movement planning and control is largely based on kinesthetic input. The purpose of the current study was to determine the characteristics of how kinesthetic-motor internal representations interact with visuo-motor representations during development.

Auditory-motor integration of subliminal phase shifts in tapping: better than auditory discrimination would predict.

Unilateral tapping studies have shown that adults adjust to both perceptible and subliminal changes in phase or frequency. This study focuses on the phase responses to abrupt/perceptible and gradual/subliminal changes in auditory-motor relations during alternating bilateral tapping. We investigated these responses in participants with and without good perceptual acuity as determined by an auditory threshold test.

Multisensory adaptation of spatial-to-motor transformations in children with developmental coordination disorder.

Recent research has demonstrated that adaptation to a visuomotor distortion systematically influenced movements to auditory targets in adults and typically developing (TD) children, suggesting that the adaptation of spatial-to-motor transformations for reaching movements is multisensory (i.e., generalizable across sensory modalities).

Electrocortical dynamics reflect age-related differences in movement kinematics among children and adults.

Previous neuroimaging and behavioral studies demonstrated structural and functional changes in the motor system across childhood. However, it is unclear what functionally relevant electrocortical processes underlie developmental differences in motor planning and control during multijoint, goal-directed movements. The current study characterized age-related differences in electrocortical processes during the performance of discrete aiming movements in children and adults.

Improvements in proprioceptive functioning influence multisensory-motor integration in 7- to 13-year-old children.

Accurate and efficient sensorimotor behavior depends on precise localization of the body in space, which may be estimated using multiple sensory modalities (i.e., vision and proprioception).

Adaptation of sound localization induced by rotated visual feedback in reaching movements.

A visuo-motor adaptation task was used to investigate the effects of this adaptation on the auditory-motor representation during reaching movements. We show that, following exposure to a rotated screen cursor-hand relationship, the movement paths during auditory conditions exhibited a similar pattern of aftereffects as those observed during movements to visual targets, indicating that the newly formed model of visuo-motor transformations for hand movement was available to the auditory-motor network for planning the hand movements. This plasticity in human sound localization does not require active cross-modal experience, and retention tests indicated that the newly formed internal model does not reside primarily within the central auditory system as suggested in past studies examining the plasticity of sound localization to distorted spatial vision.

Evidence for multisensory spatial-to-motor transformations in aiming movements of children.

The extant developmental literature investigating age-related differences in the execution of aiming movements has predominantly focused on visuomotor coordination, despite the fact that additional sensory modalities, such as audition and somatosensation, may contribute to motor planning, execution, and learning. The current study investigated the execution of aiming movements toward both visual and acoustic stimuli. In addition, we examined the interaction between visuomotor and auditory-motor coordination as 5- to 10-yr-old participants executed aiming movements to visual and acoustic stimuli before and after exposure to a visuomotor rotation.

Continuous and discontinuous drawing: high temporal variability exists only in discontinuous circling in young children.

The authors studied whether the drawing variability in young children is best explicable by (a) demands on the explicit timing system, (b) an underdeveloped ability to control limb dynamics, or (c) both. The explicit timing demands were lower in continuous drawing in comparison with the discontinuous task. The authors manipulated limb dynamics by changing the number of joints involved, with line drawing requiring fewer joints than circle drawing.

Temporal variability in continuous versus discontinuous drawing for children with Developmental Coordination Disorder.

Children with Developmental Coordination Disorder (DCD) are reported to have high temporal variability in tasks requiring precise timing. The current study examined whether this timing deficit was due to the cerebellar 'explicit timing' process in the discontinuous, but not the continuous movement. Ten children with DCD and 31 typically developing children performed continuous, discontinuous circle and line drawing tasks.

Bilateral and unilateral movement training on upper limb function in chronic stroke patients: A TMS study.

The use of activity-dependent interventions has shown some success in promoting recovery of upper limb function in chronic stroke patients. This study compared the neurophysiological and behavioural changes associated with two such rehabilitation protocols: unilateral and bilateral movement training. Twelve chronic stroke patients were randomly assigned to the two training protocols involving six daily practice sessions.

Visuomotor adaptation in children with developmental coordination disorder.

Although one of the criteria for the diagnosis of developmental coordination disorder (DCD) suggests learning impairments, there is a lack of studies investigating motor adaptation in these children. This study examined the ability of 7 children with DCD to adapt to a novel visuomotor relationship by exposing them to a 45 degrees visual feedback rotation while they performed a center-out drawing task, and compared their performance with that of 7 normally developing children. The results show that the children with DCD were less affected by the feedback distortion than the control children, and did not show aftereffects, suggesting they had a less well-defined internal model.