Changes in cortical field potentials in learning processes of audio-initiated vocalization and influences of cerebellectomy upon the vocalization in the monkey

抄録

Recording field potentials during learning processes of audio-initiated vocalization by electrodes implanted chronically on the surface and at 2.0-3.0 mm depth of the cerebral cortex and analyzing them seem useful for knowing central nervous mechanisms of the vocalization in the monkey. We have been waiting for an opportunity to record the potentials during the motor learning in a short period, because it usually takes a considerable time (3-6 months) for a naive monkey to be trained well for the vocalization. One of three monkeys, which had been fully trained for the vocalization, was found to be unable to perform the vocalization after electrode-implanting operation. We could record the potentials in the monkey during the process of learning the vocalization again. The learning process of the vocalization partly differed from audio-initiated hand movements previously reported, and there was no skill learning in the vocalization. The right cerebellar hemispherectomy eliminated the surface-negative, depth-positive (s-N, d-P) premovement potential recorded before the operation in the left face motor cortices in the three monkeys, and changed vocal tone. Scarce change was seen in reaction times in audio-initiated vocalizations before and after the operation, again differing from audio-initiated hand movements. This suggests that central nervous mechanisms in audio-initiated vocalizations differ from those in audio-initiated hand movements. These nervous mechanisms were discussed in connection with the limbic system.