Inhibition of nociceptive neurons in the intralaminar nuclei by electrical stimulation of the periaqueductal gray of the cat

Abstract

Nociceptive neurons were recorded from the intralaminar nuclei of the cat. We investigated the effects of stimulating either the periaqueductal gray (PAG) or the nucleus raphe dorsalis (NRD) on responses obtained from these neurons. Conditioning electrical stimulation of either PAG or NRD inhibited responses to some nociceptive neurons. The same conditioning stimulation also inhibited short latency responses to electrical stimulation of the mesencephalic reticular formation on these inhibited nociceptive neurons. These data suggest that PAG or NRD stimulation-produced inhibition of these neurons may be partially mediated by an ascending pathway, in addition to the well-known descending pathways.