TOPOGRAPHICAL DISTRIBUTION AND FUNCTIONAL-PROPERTIES OF CORTICALLY INDUCED RHYTHMICAL JAW MOVEMENTS IN THE MONKEY (MACACA-FASCICULARIS)
TOPOGRAPHICAL DISTRIBUTION AND FUNCTIONAL-PROPERTIES OF CORTICALLY INDUCED RHYTHMICAL JAW MOVEMENTS IN THE MONKEY (MACACA-FASCICULARIS)
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DOI：
10.1152/jn.1989.61.3.635
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发表时间：
1989-03-01
影响因子：
2.5
通讯作者：
SESSLE, BJ
中科院分区：
文献类型：
--
作者：
HUANG, CS;HIRABA, H;SESSLE, BJ
The lateral part of the pericentral cortex of both hemispheres in three awake monkeys was explored with intracortical microstimulation (ICMS) using short trains (T/S; 200-.mu.s pulses at 333 Hz for 35 ms, .ltoreq. 30 .mu.A) and long trains (C/S; 200-.mu.s pulses at 50 Hz for 3 s, .ltoreq. 60 .mu.A). In both hemispheres of one of these monkeys, the responsiveness of single cortical neurons to stimulation of the orofacial region was tested at the same intracortical sites where ICMS was applied. Movements were evoked from four physiologically defined cortical regions: the primary face motor cortex (MI), the primary face somatosensory cortex (SI), the principal part of the cortical masticatory area (CMAp) which was located in the precentral gyrus lateral to MI, and a deep part of the cortical masticatory area (CMAd) which was located in the inferior face of the frontal operculum. Two types of cortically induced movements were observed: a single twitch movement and EMG activity of the orofacial muscles that was evoked by T/S at a short latency (10-45 ms) and rhythmical jaw movements (RJMs) which were only evoked by C/S. RJMs were evoked at C/S frequencies ranging from 20 to 300 Hz. At movement threshold, the frequency of the cortically induced RJMs varied from 0.7 to 1.5 Hz and usually increased with the increase of C/S intensity up to 2 times movement threshold. The vertical amplitude of RJMs was also stimulus dependent, and at movement threshold it ranged from 3 to 9 mm. The movement patterns of the cortically induced RJMs remained constant during the course of C/S but could be differentiated in the frontal plane into ipsilateral- (RJMi), vertical- (RJMi), and contralateral- (RJMc) directed movements. These three different patterns of RJMs were associated with different patterns of masticatory muscle activity. Each cortical region contained many sites from which RJMs could be induced (so-called RJM sites). The RJMi sites were more numerous than RJMc sites in all regions except SI and were located anterolateral or lateral to the RJMc sites in each region; the RJMv sites were scattered throughout each cortical region. In MI, C/S elicited RJMs from 94 intracortical sites from which short-latency twitch movements could also be evoked by T/S. Most of these RJM sites were located in the rostral part of MI. Many neurons located at RJM sites in MI may receive mechanoreceptive afferent inputs which predominantly derive from an orofacial area closely associated with the twitch movements evoked by T/S at the site of neuronal recording. In CMAp, T/S evoked a short-latency muscle twitch movement at 53 intracortical sites, but C/S evoked RJMs from many more sites (426 in toto). The CMAp received mechanoreceptive afferents mainly from ipsilateral or bilateral intraoral regions. RJMs could be evoked from 26% of the sites receiving orofacial afferent inputs. In SI, although T/S was ineffective in evoking any short-latency muscle twitch, C/S evoked RJMs from 389 sites. SI predominantly received mechanoreceptive afferent inputs that were organized in a somatotopic pattern. RJMs were evoked from 14% of the sites receiving these afferent inputs. In CMAd, no short-latency muscle twitch was evoked by T/S, but C/S evoked RJMs from 368 sites. No afferent input could be demonstrated at these RJM sites. These findings of an extensive representation of RJMs in the pericentral region suggest that the cerebral cortex plays an important role in mastication in the primate. The input-output features further raise the possibility that the four cortical regions from which RJMs can be induced may be differentially involved in the production and patterning of mastication.
