Article

Predictable sensorimotor perturbations can lead to cerebellum-dependent
adaptation--i.e., recalibration of the relationship between sensory input and
motor output. Here we asked if the cerebellum is also needed to recalibrate the
relationship between two sensory modalities, vision and proprioception. We
studied how people with and without cerebellar damage use visual and
proprioceptive signals to estimate their hand's position when the sensory
estimates disagree. Theoretically, the brain may resolve the discrepancy by
recalibrating the relationship between estimates (sensory realignment).
Alternatively, the misalignment may be dealt with by relying less on one sensory
estimate and more on the other (a weighting strategy). To address this question,
we studied subjects with cerebellar damage and healthy controls as they performed
a series of tasks. The first was a prism adaptation task that involves motor
adaptation to compensate for a visual perturbation and is known to require the
cerebellum. As expected, people with cerebellar damage were impaired relative to
controls. The same subjects then performed two experiments in which they reached
to visual and proprioceptive targets while a visuoproprioceptive misalignment was
gradually imposed. Surprisingly, cerebellar patients performed as well as
controls when the task invoked only sensory realignment, but were impaired
relative to controls when motor adaptation was also possible. Additionally,
individuals with cerebellar damage were able to use a weighting strategy
similarly to controls. These results demonstrate that, unlike motor adaptation,
sensory realignment and weighting are not cerebellum-dependent.
CI - Copyright (c) 2012 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS