Spontaneous rhythms of perceptual motor performance in intact and damaged brain of man.

A simple 15-sec maximal speed tapping task was administered every minute for 20 min to 69 healthy subjects and to 53 patients with mental disorders embodying six diagnostic categories including mental retardation. Analysis of the results showed age and diagnosis, but not gender, to be significant variables. Autocorrelation analysis of the results revealed the existence of spontaneous ultradian cycles of recurrence for all subjects, the frequency and amplitude of which discriminated the healthy subjects and only non-organically sick patients from patients with organic neurological deficits. 'Scatter' scores representing deviations about the mean tapping scores showed similar cyclic characteristics. The relationship between these cycles of motor performance and neural clock controlling perception is discussed.