Authors: Daniel Säfström Benoni B Edin
Publish Date: 2006/02/28
Volume: 173, Issue: 3, Pages: 487-497
Abstract
For sensorimotor transformations to be executed accurately there must be mechanisms that can both establish and modify mappings between sensory and motor coordinates Such mechanisms were investigated in normal subjects using a reachtograsp task First we replaced the normal input of visual information about object size with auditory information ie we attempted to establish an ‘audiomotor map’ The size of the object was log linearly related to the frequency of the sound and we measured the maximum grip aperture MGA during the reaching phase to determine if the subjects had learned the relationship Second we changed the frequency–object size relationship to study adaptation in the newly acquired map Our results demonstrate that learning of an audiomotor map consisted of three distinct phases during the first stage ∼10–15 trials subjects simply used MGAs large enough to grasp any reasonably sized object and there were no overt signs of learning During the second stage there was a period of fast learning where the slope of the relationship between MGA and object size became steeper until the third stage where the slope was constant In contrast when sensorimotor adaptation was studied in the established audiomotor map there was rapid learning from the start of a size perturbation We conclude that different learning strategies are employed when sensorimotor transformations are established compared to when existing transformations are modifiedThis work was supported by grants from the Swedish Medical Research Council projects 08667 and K200604X20031013 and the 6th Framework Program of EU IST001917 We thank Göran Westling for constructing the experimental apparatus Anders Bäckström for computer support
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