[Effects of stimulation of the rabbit caudate nucleus on units responsive to noxious stimuli in the parafascicular nucleus of the thalamus].
摘要
The discharges of parafascicular units excited by noxious stimuli(PfPE)andinhibited by those(PfPI)in 51 conscious and curarized rabbits were recorded.Theeffects of stimulation of the dorsal part of the head of caudate nucleus(DHCN)on thespontaneous and nociceptive discharges of these units were studied.(1)Among the 28PfPE units,the spontaneous discharges of 19 units were inhibited by caudate stimu-lation,those of 2 units were enhanced,while those of the remaining 7 units showed nochange.Among the 6 PfPI units,the spontaneous discharges were enhanced in 5 unitsand unchanged in 1 unit.(2)Among the 38 PfPE units,the nociceptive discharges wereenhanced in 2 units,inhibited in 30 units,while showed no change in 6 units.This in-hibitory effect occurred immediately at the beginning of the stimulation of DHCN andlasted for 700—1600 ms in 8 out of 12 of the 30 inhibited units.Among the 10 PfPI units,nociceptive discharges were enhanced in 7 units and no effect was observed in 2 units.The results described above suggest that DHCN plays a modulatory actionin the integration of pain information in PfPE and PfPI units and that this actionmay be carried out via both direct and indirect pathways,according to the relativelyshort latent period and long duration of this inhibitory effect.