EFFECTS OF LIMBIC SYSTEM STIMULATION ON NEUROSECRETORY NEURONS OF SUPRAOPTIC NUCLEUS

Abstract

This chapter discusses that electrical stimulation of structures in the olfactory system affected the majority of neurosecretory cells in supraoptic nucleus (SON). The observations that some neurons are “driven” by stimulation of olfactory tubercle, prepyriform cortex, and some amygdaloid nuclei indicate that there are strong connections between these areas for impulse transmission. The long latency of these “evoked” responses suggests rather long polysynaptic pathways to SON. However, in the majority of SON neurons, the effect exerted by electrical stimulation of the olfactory system was inhibitory in nature and often its latency was shorter than that of the excitatory response. Even in those neurons receiving excitatory input, their spontaneous discharges were inhibited for several 100 msec following excitation of a short period. Morphological studies indicate that direct descending pathway from the olfactory bulb passes via the olfactory paleocortex—pyriform cortex and olfactory tubercle—and the medial forebrain bundle to the lateral preoptic hypothalamic area.