Suppression of pineal multiunit response to flash after habenular lesion in quail.

Habenular nuclei were completely destroyed in male photostimulated and nonphotostimulated quail (Coturnix coturnix japonica). Lesion of the nuclei habenulae led to a markedly increased pineal multiunit activity (MUA) pattern in both long and short daily photoperiods compared to control values. Intact, as well as habenular lesioned birds, showed a lower level of pineal MUA under long-day rearing than under short-day rearing. The decrease in pineal firing rates found in controls under repetitive flash-light stimulations was suppressed in quail bearing habenular lesions. Data are compared to results obtained in sympathectomized and blinded birds. It is suggested that some acute photic information might reach the pineal organ through retinal receptors and habenular pathways. However chronic influence of lighting on pineal MUA, mediated by the retina, does not seem to involve habenular or cervical sympathetic pathways in quail.