Anticipatory postural adjustments are attenuated in spinocerebellar degeneration

Abstract

Anticipatory postural adjustments (APAs) can be seen in postural muscles prior to self-triggered or self-inflicted postural perturbations. Their assumed role is to counteract the expected mechanical effects of the perturbation in a feedfoward manner. Timmann and Horak (2001) addressed the role of cerebellum on APAs to compare patients of spinocerebellar degeneration (SCD) with normal subjects. They suggest that the cerebellum may be less influential in APAs. However, this suggestion is still controversial because the cerebellum is well known to use the feedfoward mechanisms to regulate movements. Stepping tasks used in the previous study could not separate focal voluntary movements and postural activity adequately. It is consider that APAs was contaminated with focal movement in this case.In the present study, we investigated the change of APAs in the SCD patients by using the upper limb elevation task in that focal movement and postural activity are separated sufficiently. As the results, the SCD patients showed significantly smaller APAs amplitudes. These data suggest the important role of the cerebellum on generation of APAs. [Jpn J Physiol 54 Suppl:S185 (2004)]