Multiple-Unit Activity in the Pineal Gland of the Japanese Quail: Spontaneous Firing and Responses to Photic Stimulations

Abstract

The present study was devoted to the recording ofspontaneous multiple-unit discharges in the pineal gland of the quail to investigate the influence of light stimulation on the multiunit pineal activity. The spontaneous rate of firing depended upon the size of the macro-microelectrodes (86 spikes/10 sec with 30 µm electrodes; 25 spikes/10 sec with 15 µm electrodes). Light flashes resulted in a marked inhibition of electrical discharges recorded from the same cell populations (54 vs 86 and 14 vs 25 spikes/10 sec). A bilateral section of optic nerves suppressed the inhibiting response of pineal activity to illumination and allowed the spontaneous firing rate to be increased almost 4-fold in blinded quail compared to intact controls.