Unit activity of bulbar raphe nuclei and reticular formation in cats

Abstract

Spontaneous activity and single unit responses of the bulbar raphe nuclei (NR) and mesencephalic reticular formation (MRF) were studied in unanesthetized cats. In addition to the general features, a number of special features of the unit activity of these two structures were discovered: a) in most cases NR neurons respond predominantly or entirely to cutaneous stimulation of 3 to 4 limbs; b) spontaneous activity (SA) of NR neurons is more regular and less variable in time than that of MRF neurons. Under the influence of various peripheral stimulations the spontaneous activity of NR neurons briefly increases in frequency without any change in firing pattern, whereas the increase in frequency of MRF neurons occurs for much longer and is accompanied by marked changes in spontaneous activity c) NR neurons respond to all peripheral stimuli used by an absolutely uniform, short and compact volley of spikes, whereas MRF neurons respond differently to each stimulus, with various numbers of spikes and different firing patterns. These peculiarities of NR unit activity are evidently attributable to its simpler synaptic organization than that of MRF.