Time resolution for visual information processing in Parkinson'sdisease

It has been suggested that a deficit in timing could be thecause of the sensory disturbances reported for Parkinson's disease. Totest this hypothesis the temporal discrimination thresholds in fourvisual tasks were used to study 45 healthy young people, 14 healthyelderly people, and 17 patients with Parkinson's disease. In thesetasks, subjects watched a computer controlled light emitting diodedisplay and pushed a button when the visual event previously specifiedby the researcher was perceived. The time between successive imagesrequired to discriminate a visual detail was accurately quantified. Intwo of the four tasks, the time for visual processing of imagesequences was longer in the elderly group than in the young group. Nosignificant differences were found between patients with Parkinson'sdisease and their age matched controls for any of the four tasks.Present data show normal temporal discrimination and no slowing in theinitial steps of visual processing in Parkinson's disease.