Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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Postural equilibrium is known to be controlled by sensorimotor reflexes and automatic control loops but also depends on high-level body representation in space, probably implicating the right temporoparietal cortex. Indeed, short-term prism adaptation to a 10 degrees rightward visual shift has been shown to reduce predominant postural imbalance in patients with right hemisphere damage, as it did for neglect symptoms. These effects are likely to be explained by a high level effect of prism adaptation on body and space representation, rather than by a sensorimotor effect. ⋯ Indeed, only adaptation to a leftward visual shift induced significant rightward postural bias in normal subjects. The rightward postural lateral displacement was negatively correlated with the visual vertical. Both transfer and direction specific effect of visuo-manual adaptation to prisms on postural control suggest that effects of adaptation act more on high-level postural control linked to body representation in space or at least reveal close interaction between sensorimotor plasticity and body representation.
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It is well known that sensorimotor adaptation will transfer from the practiced to the unpracticed arm, which has been taken as evidence that adaptation is located in the brain before the divergence point for left and right arm control. We now explore whether adaptation will transfer between different movement categories as well. ⋯ This benefit of pointing persisted when the use of cognitive strategies was minimized by a concurrent, attention-demanding task, but it was lost when pointing amplitudes were very small. We conclude that adaptation is located in the brain before the divergence point for different movement categories, and that movements with a large ballistic component facilitate adaptation transfer.