1995 Fiscal Year Final Research Report Summary
Nociceptive processing systems in the Cingulate cortex
| Project/Area Number |
06671851
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Functional basic dentistry
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
TOKA Kazuo Department of Oral Physiology, Faculty of Dentistry, Tokyo Medical and Dental University Lecturer, 歯学部, 講師 (80134708)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Cingulate cortex / affective system / pain / analgesia / rat |
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| Research Abstract |
Extracellular recording was made from single cells in the anterior cingulate cortex (ACCX) which projected descendingly to the periaqueductal gray matter (PAG) in barbiturate-anesthetized rats. After mechanical stimulation (nonnoxious von Frey heir and noxious pinch), ACCX neuronms were divided into two types : one is wide dynamic range (WDR), and the other is noxious specific (NS) neurons. Almost all of these neurons were found in the layr V of the area 24. None of the low threshold mechanoreceptive neurons (LTM) neurons were found. Most units of the ACCX had broad receptive fields of the both sides, and those of the WDR neuron were significantly larger than those of the NS ones (Wilcoxon rank test, p<0.05). About a half of the WDR (46%) and a majority of the NS (89%) neurons excited to heat stimuli applied to their mechanical receptive fields. In the NS neurons, off-response was often obswerved after the cessation of the heat stimulation. Threshold value of the heat stimuli for the WDR neuron was 44.5-2.7 C (mean-SD,n=6), and that for the NS one was 46.4-2.1 (n=17). These results show that all the descending ACCX neurons are nociceptive, at least receiving mechanical and heat noxious inputs, suggesting that the ACCX plays a significant role for processing noxious information using negative feedback circuits involving in the PAG system.
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