Mini-symposium on Motor Control and Vision

sponsored by "Fondation JED Belgique"

ICTEAM Institute, Dept. Mathematical Engineering

Institute of Neuroscience, COSY

Contact and registration: Philippe LEFEVRE

 

Monday July 20, from 13:30 to 18:30, Louvain-la-Neuve

Program at a glance:

Detailed Program

13:30 Prof. Andrew GORDON (Columbia University, New York):

"Translational motor control: from grasp mechanisms to rehabilitation in cerebral palsy"

Effective rehabilitation strategies of the upper extremity must take into account understanding of anticipatory and feedback control strategies of manipulated objects in both typically developed adults, as well as the mechanisms underlying motor impairments in subjects with movement disorders. Such control of fingertip forces will be reviewed in the context of motor learning and movement flexibility. This will be followed by how this understanding may be translated into potential clinical applications, and the efficacy of such approaches for children with cerebral palsy.

14:10 Prof. Jean-Jacques ORBAN DE XIVRY (KU Leuven):

"Artificial manipulation of human motor memories"

It is widely recognized that adapting an identical reaching movement simultaneously to conflicting dynamical environments is quite difficult due to the interference. However, several recent works have demonstrated that simultaneous adaptation is not impossible: For example, we have showed that participants can easily develop distinct motor memories for a reaching movement depending on whether the opposite arm is stationary or moving (i.e., unimanual or bimanual movement) (Nozaki et al., Nat Neurosci 2006). These results suggest that distinct neural representations of a movement depending on different behavioral contexts are associated with different motor memories. That is, the distinct motor memories observed for unimanual and bimanual movements would stem from their partially distinct neural representations (Donchin et al., J Neurophysiol 2002). Here, to confirm this idea in a more causal way, we tried to examine if artificially induced changes in neural representations using transcranial direct current simulation (tDCS) could contribute to the formation and retrieval of distinct motor memories. Sixteen participants performed forward reaching movement (10 cm) while holding a handle of manipulandum with right hands (KINARM End-Point Lab, Bkin Technologies, Canada). Clockwise (CW) or counter-clockwise (CCW) force field was applied to the handle in a blocked manner (Each block consisted of 20 trials for each force field). tDCS was applied by electrodes placed over left and right primary motor cortices (M1) (i.e., bihemispheric tDCS). In the 6 blocks of training session, the CW or CCW force field was associated with anodal and cathodal tDCS to left M1, respectively. Following the training session, 2 blocks of test session were set up to assess whether the motor memory acquired in the training session was read-out according to the polarity of tDCS. To quantify the acquired motor memories, we adopted the error clamp method in which any force perpendicular to the force channel during movement was measured as aftereffect of the learning. Surprisingly, we observed that the aftereffect was clearly modulated with the polarity of tDCS. In contrast, tDCS in the test session was ineffective to modulate the aftereffect for the participants who trained the force fields with sham tDCS. These results indicate that tDCS could help to differentiate motor memories between the conflicting force fields and to retrieve appropriate motor memories. The present results are also consistent with our hypothesis that distinct neural representations of identical movements can contribute to develop the distinct motor memories.

14:50 Prof. Guillaume MASSON (Institut de Neurosciences de la Timone, Marseille):

"Predictive coding and motion trajectories in area V1 of macaque monkeys (modeling and imaging)"

Abtract: coming soon

15:30 : Coffee Break (hall Euler)

16:30 Caroline EGO (ICTEAM/INMA and IoNS/COSY):

"Maturation of visual tracking in typically developing children and individuals with cerebral palsy and autism spectrum disorder", PhD thesis defense.

Vision is probably our most essential sense. One particularity of our environment is that it is made of moving objects. In order to get a clear vision of what surrounds us, we need a good ability to visually track moving targets. In this thesis, we studied the development of visual tracking abilities using oculomotor tasks that combine the two essential types of orienting eye movements that are smooth pursuit and saccades. As eye movements are controlled by muscles commanded through complex brain circuits, the goal was to better understand the development of oculomotor control with age. The evaluation of the typical development is also essential to detect deficits in patients. In particular, we were interested in this thesis in characterizing the potential disorders of eye movements in children with cerebral palsy or autism spectrum disorder. Altogether, this thesis illustrates how eye movements can be used to better understand some developmental processes and disabilities.