| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1987: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
The periodontal mechanosensitive (PM) units were investigated to clarify the information processing mechanism of somesthetic sensation in the thalamus and cerebral cortex of the cat. Fifteen cats were anesthetized with chloralose (140mg/kg, i.v.). PM units responsive to mechanical stimulation of the teeth were recorded from the thalamus and somatosensory cortex with tungsten microelectrodes through a liquid paraffin chamber fixed on the cranium. Three hundred and fifty-five units were recorded from the PM area which was located at the medioventral aspect of the VPM nucleus in the thalamus. Of all the thalamic units, 192 (54,2%) were a rapidly adapting type, 155 (43.7%) were slowly adapting and the remaining 7 units were unclassified. On the other hand, sixty-two units were recorded from the PM area of somatosensory cortex (SI) which was located outside the coronal sulcus. Of the cortical units, 5(8%) were slowly adapting type and 57(91.9%) were rapidly adapting.
The units were represented as the number of the quadrants on the dental arches of both jaws occupied by the receptive fields. Of the thalamic units, the one-quadrant, two-quadrant and four-quadrant units were 188(53.1%), 106(29.9%) and 57(16.1%), and of the cortical units, 27(43.5%), 20(32.3%) and 7(17.5%), respeectively. Of these three groups, the rates of slowly adapting untits in the thalamic neurons were 59.2%, 33.3% and 10.7%, respectively. Those of cortical neurons were 14.8%, 5.0% and 0%. These results suggest that the thalamic and cortical PM neurons might recieve many convergent fibers carrying mechanosensory informaton.
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