Perceptual timing in cerebellar degeneration

This study examined rime perception in 12 patients with cerebellar degeneration (CD) and in 13 normal controls (NC). We used a time bisection procedure with four interval conditions (100-900 msec; 8-32 sec; 100-600 msec; 100-325 msec). Each subject´s bisection point, discrimination ability (the Weber ratio) and precision (the inverse of the proportion of unexplained variance) was calculated for each condition. CD patients´ performance on the 100-900 msec time bisection condition suggested a possible time discrimination deficit, which was confirmed with intervals in the range of 100-600 msec. Time discrimination was normal on the 100-325 msec condition and impaired on the 8-32 sec bisection task. However, when discriminating long intervals, CD patients also showed a precision deficit, which points to impaired sustained attention and/or decision processes. Our findings corroborate the view that cerebellar timing processes are not limited to the motor system but are also used in perceptual computations. Copyright