Parametric relationships of individual digit movements to neuronal discharges in primate magnocellular red nucleus.

Single units were recorded in the magnocellular red nucleus (RNm) while digit movements were monitored in a monkey performing on an individual digit device. The monkey was trained to press switches for water reward while optical systems of infrared emitters and diodes were taped to thumb, index, middle and ring digits for monitoring movements. Of 53 neurons recorded while operating the individual digit device, 9 showed statistically significant parametric relationships with movement velocity and duration. Onset of activity preceded movement by an average of 90 +/- 26 ms. This result suggests that a small group of neurons in the forelimb area of RNm in the monkey is parametrically related to individual digit movements, even though the majority of neurons are related to grouped movements of the hand and digits as previously reported.