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Titolo:
THALAMIC VPM NUCLEUS IN THE BEHAVING MONKEY .3. EFFECTS OF REVERSIBLEINACTIVATION BY LIDOCAINE ON THERMAL AND MECHANICAL DISCRIMINATION
Autore:
DUNCAN GH; BUSHNELL MC; OLIVERAS JL; BASTRASH N; TREMBLAY N;
Indirizzi:
UNIV MONTREAL,FAC MED DENT,CTR RECH SCI NEUROL,DEPT STOMATOL,CP 6128,SUCC A MONTREAL H3C 3J7 QUEBEC CANADA INST NATL SANTE RECH MED RECH NEUROPHYSIOL PHARMACOL F-7514 PARIS FRANCE
Titolo Testata:
Journal of neurophysiology
fascicolo: 5, volume: 70, anno: 1993,
pagine: 2086 - 2096
SICI:
0022-3077(1993)70:5<2086:TVNITB>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
SUPERIOR COLLICULUS; INTRALAMINAR THALAMUS; MEDIAL THALAMUS; NEURONS; RAT; RESPONSES; RESPONSIVENESS; SUBMEDIUS; CORTEX; COMPARTMENTS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
43
Recensione:
Indirizzi per estratti:
Citazione:
G.H. Duncan et al., "THALAMIC VPM NUCLEUS IN THE BEHAVING MONKEY .3. EFFECTS OF REVERSIBLEINACTIVATION BY LIDOCAINE ON THERMAL AND MECHANICAL DISCRIMINATION", Journal of neurophysiology, 70(5), 1993, pp. 2086-2096

Abstract

1. The present study evaluates the necessity of the ventroposterior medial thalamic nucleus (VPM) for discrimination of the intensity of noxious heating, innocuous cooling, and innocuous tactile (airpuff) stimulation of the maxillary skin. 2. Two rhesus monkeys were trained to detect small differences (< 1.0-degrees-C) in the intensity of noxious heat (near 46-degrees-C) and innocuous cold (near 30-degrees-C) as well as differences in the force of an airpuff applied to the skin over the maxilla. As a control the monkeys also detected small differences in the intensity of a white light. Lidocaine hydrochloride (2%) was microinjected into regions of thalamus where single-unit recordings had identified neuronal responses to the noxious heating and/or cooling stimuli. The effectiveness of the anesthetic blockade was monitored by multiunit recordings using microelectrodes positioned 1-3 mm from the orifice of the injection cannula. The monkey's ability to detect near-threshold changes in stimulus intensity was compared before and after each injection. 3. During six experimental sessions, single injections of 1-4 mul lidocaine near the dorsomedial border of VPM did not significantly alter the monkey's ability to detect small changes in the intensity of noxious heat, cool, airpuff, or visual stimuli despite neurophysiological evidence that spontaneous neuronal activity was blocked within parts of VPM. 4. During three experiments, dual simultaneous microinjections of lidocaine (delivered through 2 microcannulae separated by approximately 1 mm) resulted in profound deficits in noxious heat discrimination, with lesser deficits in cool and airpuff discrimination; visual discrimination was never altered. Monitoring of adjacent microelectrodes revealed that although activity ventral to the injection sites was blocked, activity in medial thalamic nuclei, implicated in nociceptive processing, was probably not altered by these injections. 5. These data suggest that VPM is important for the perception of noxious and innocuous thermal stimuli as well as for the perception of tactile stimuli. However, considering the ineffectiveness of small single microinjections of lidocaine, it appears that some critical proportion of VPM must be inactivated to disrupt thermal or tactile discrimination, possibly because of overlapping receptive field properties of neurons in different areas of the nucleus.

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Documento generato il 04/07/20 alle ore 03:54:11