Multiple unit activity patterns of neuronal populations in gonadotropic areas of the quail hypothalamus: spontaneous and photically-induced firing.

Multiple-unit activity (MUA) was obtained from neuronal pools in the gonadotropic hypothalamus of quails. A special device allowed for exploration of various hypothalamic structures in unanesthetized birds. All recording sessions were made in the dark. Spontaneous and flash light-evoked MUAs were recorded from both tuberal and dorsal gonadotropic areas, either in the morning or in the afternoon, and were compared to extragonadotropic firing patterns. Firing rates (spikes/10 sec) and integrated MUA (200 addresses) provided distinctive spontaneous neuronal activities for various cell clusters. These spontaneous salient features appeared to be changeable throughout the photoperiod. Flash stimulations resulted in a marked increase in MUA recorded from the gonadotropic regions of the hypothalamus.