1990 Fiscal Year Final Research Report Summary
Studies on Function and its Disorder of the Frontal Association Cortex
| Project/Area Number |
62440024
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Neurophysiology and muscle physiology
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| Research Institution | Kyoto University |
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Principal Investigator |
SASAKI Kazuo Faculty of Medicine, Kyoto University Professor, 医学部, 教授 (20025539)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUNO Noboru Faculty of Medicine, Kyoto University Profeesor, 医学部, 教授 (10025596)
GENBA Hisae Faculty of Medicine, Kyoto University Lecturer, 医学部, 講師 (00108987)
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| Project Period (FY) |
1987 – 1990
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| Keywords | frontal association cortex / cortical field potential / visually initiated movement / color discrimination task / event-related potential / monkey / human |
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| Research Abstract |
We investigated function of the frontal association cortex and its disorder in monkeys, and then in humans on the basis of data obtained by monkey experiments. The results will be summarized in two main topics as follows.
1. The frontal association cortex for decision (judgment) and suppressor action A monkey was tasked with go/no-go reaction-time hand movement with discrimination between two different color light stimuli. Visual stimulus of a color was accompanied by reward when the monkey lifted a lever by its hand within 500 ms duration of the stimulus, whereas that of another color was not. When the monkey gradually ceased in responding to the latter (no-go) stimulus, a potential appeared and developed in the prefrontal cortex of both hemispheres, specifically to the no-go stimulus, called 'no-go potential'. The potential is composed of surface-negative, depth-positive (s-N, d-P) deflections at a latency of 85-150 ms and localized in the dorsal bank of the principal sulcus and the r
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ostroventral corner of the prefrontal cortex. Modes of appearance and development of the potential suggest that the activity of the cortical loci is related to decision or judgment not to move and to subsequent suppression of the go reaction. The suppressor action was substantiated by stimulation experiment of the cortical loci.
2. The frontal association cortex for expectancy of coming stimulus and mental concentration We gave warning-imperative stimuli with a fixed time interval (e. g. ls) to a monkey so that it could lift a lever immediately after the onset of imperative stimulus. In fact, the monkey, after enough trained, moved at very short latencies. Following initial visual evoked potentials on the warning stimulus, s-N, d-P sustained slow potentials toward the imperative stimulus were recorded in wide areas of the prefrontal and premotor cortices in both hemispheres. The short latency movement was scarcely in fluenced by cerebellar hemispherectomy ipsilateral to the moving hand, which was quite different from the case of simple reaction-time hand movement. This may imply that the sustained activity of the frontal association cortex on the warning-imperative stimulus can overcome cerebellar deficiency to some extent.
3. Studies in human subjects No-go potential was recorded also from the human scalp on the same go/no-go task. It spreads over the frontal part of scalp widely with the maximum at the vertex (Fz). The warning-imperative stimulus induces contingent negative variation (CNV) on the human scalp. Sustained activities of the frontal association cortex must be related to mental concentration on the coming stimulus. Less
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