Studies on cognitive functions by cortical field potential recording

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Monkeys were trained to perform self-paced finger, toe, mouth, hand or trunk movements. Cortical field potentials were then recorded by electrodes implanted on the cortical surface and at a depth of 2.0-3.0 mm from the surface in many cortices. Surface-negative (s-N), depth-positive (d-P) potential (readiness potential) appeared about 1 s before the start of every self-paced movement in the rostral and caudal banks of the intraparietal sulcus in the parietal cortex, as well as the premotor, motor and somatosensory cortices. The potential was bigger in the hemisphere contralateral to the moving finger, toe or hand than in the ipsilateral one in the motor, somatosensory and parietal cortices. The readiness potential in the premotor cortex was more marked on a patterned movement of rotating neck and lumbar region simultaneously to the left or right than a simple movement of moving hand or toe.Monkeys were also trained to move hand in response to imperative visual stimulus (IS) given 1 s after warning visual stimulus (WS) (CNV task). A s-N, d-P potential (CNV-like potential) was recorded in the parietal cortex as well as the prefrontal, premotor, motor and somatosensory cortices in the monkey during the CNV task. Moreover monkeys were trained for go/no-go reaction time hand movements with discrimination of different color stimuli, and then go/no-go reaction time hand movements with discrimination of different location stimuli. A s-N, d-P potential (no-go potential), which was considered to be related to judgment not to move and suppression of motor execution, was recorded in the dorsal bank of the principal sulcus in the monkey on both the go/no-go hand movements. Such the no-go potential was not recorded in the parietal cortex.Heart rate number and the area of pupil were measured in the monkey on the above-mentioned tasks, but any special findings were not obtained.