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Specificity of reflex adaptation for task-relevant variability.

Franklin, DW and Wolpert, DM (2008) Specificity of reflex adaptation for task-relevant variability. J Neurosci, 28. pp. 14165-14175.

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The motor system responds to perturbations with reflexes, such as the vestibulo-ocular reflex or stretch reflex, whose gains adapt in response to novel and fixed changes in the environment, such as magnifying spectacles or standing on a tilting platform. Here we demonstrate a reflex response to shifts in the hand's visual location during reaching, which occurs before the onset of voluntary reaction time, and investigate how its magnitude depends on statistical properties of the environment. We examine the change in reflex response to two different distributions of visuomotor discrepancies, both of which have zero mean and equal variance across trials. Critically one distribution is task relevant and the other task irrelevant. The task-relevant discrepancies are maintained to the end of the movement, whereas the task-irrelevant discrepancies are transient such that no discrepancy exists at the end of the movement. The reflex magnitude was assessed using identical probe trials under both distributions. We find opposite directions of adaptation of the reflex response under these two distributions, with increased reflex magnitudes for task-relevant variability and decreased reflex magnitudes for task-irrelevant variability. This demonstrates modulation of reflex magnitudes in the absence of a fixed change in the environment, and shows that reflexes are sensitive to the statistics of tasks with modulation depending on whether the variability is task relevant or task irrelevant.

Item Type: Article
Uncontrolled Keywords: Adaptation, Physiological Adult Analysis of Variance Biomechanical Phenomena Conflict (Psychology) Electromyography Feedback Female Functional Laterality Hand Humans Male Movement Muscle Contraction Muscle, Skeletal Posture Psychomotor Performance Reaction Time Reflex Time Perception Vision, Ocular
Divisions: Div F > Computational and Biological Learning
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 18:57
Last Modified: 19 Apr 2018 02:29