We recorded the activity of cerebellar cells (PCs), primary motor cortical (MI) neurons, and limbs EMG signals while monkeys executed a sequential reaching and button pressing task. PC simple spike discharge generally correlated well with the activity of one or more forelimb muscles. Surprisingly, given the inhibitory projection of PCs, only about one quarter of the correlation were negative. The largest group of neurons burst during movement and were positively correlated with EMG signals, while another significant group burst and were negatively correlated. Among the PCs that paused during movement most were negatively correlated with EMG. The strength of this various correlations was somewhat weaker, on average, than equivalent correlations between MI neurons and EMG signals. On the other hand, there were no significant differences in the timing of the PCs and MI neurons. PC discharged was modulated largely in phase, or directly out of phase, with muscle activity. The nearly synchronous activation of PCs and muscles yielded positive correlations, despite the fact that the synaptic effect of the PC discharge is inhibitory. The apparent function of this inhibition is to restrain activity in the limb premotor network, shaping it into a spatiotemporal pattern that is observed timing suggests that the cerebellar cortex learns to modulate PC discharge predictively. Through the cerebellar nucleus, this PC signal is combined with underlying cerebral cortex cortical signal. In this matter the cerebellum refines the descending command as compared with the relatively crude version generated when the cerebellum is damaged.
|Original language||English (US)|
|Number of pages||9|
|Journal||Archives italiennes de biologie|
|State||Published - Jan 1 2002|
ASJC Scopus subject areas
- Cell Biology