Distinct mechanisms explain the control of reach speed planning: evidence from a race model framework

Venkataratamani, Prasanna Venkhatesh and Murthy, Aditya (2018) Distinct mechanisms explain the control of reach speed planning: evidence from a race model framework. In: JOURNAL OF NEUROPHYSIOLOGY, 120 (3). pp. 1293-1306.

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Abstract

Previous studies have investigated the computational architecture underlying the voluntary control of reach movements that demands a change in position or direction of movement planning. Here we used a novel task in which subjects had to either increase or decrease the movement speed according to a change in target color that occurred randomly during a trial. The applicability of different race models to such a speed redirect task was assessed. We found that the predictions of an independent race model that instantiated an abort-and-replan strategy was consistent with all aspects of performance in the fast-to-slow speed condition. The results from modeling indicated a peculiar asymmetry, in that although the fast-to-slow speed change required inhibition, none of the standard race models was able to explain how movements changed from slow to fast speeds. Interestingly, a weighted averaging model that simulated the gradual merging of two kinematic plans explained behavior in the slow-to-fast speed task. In summary, our work shows how a race model framework can provide an understanding of how the brain controls different aspects of reach movement planning and help distinguish between an abort-and-replan strategy and merging of plans. NEW & NOTEWORTHY For the first time, a race model framework was used to understand how reach speeds are modified. We provide evidence that a fast-to-slow speed change required aborting the current plan and a complete respecification of a new plan, while none of the race models was able to explain an instructed increase of hand movement speed, which was instead accomplished by a merging of a new kinematic plan with the existing kinematic plan.

Item Type:	Journal Article
Publication:	JOURNAL OF NEUROPHYSIOLOGY
Publisher:	AMER PHYSIOLOGICAL SOC
Additional Information:	Copy right for this article belong to AMER PHYSIOLOGICAL SOC
Keywords:	kinematic planning; movement control; race models; reach movements; speed redirect
Department/Centre:	Division of Biological Sciences > Centre for Neuroscience
Date Deposited:	15 Nov 2018 14:11
Last Modified:	15 Nov 2018 14:11
URI:	http://eprints.iisc.ac.in/id/eprint/61073

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