Neural control of pineal function in mammals and birds.

Pineal function in mammals is regulated by a system with four major neural components. The first is a retinohypothalamic projection from the ganglion cells of the retina to the suprachiasmatic nucleus of the hypthalamus. The suprachiasmatic nucleus appears to function as a circadian oscillating system projecting into the hypothalamus and this represents the second component. The third component is constituted of a brainstem pathway from the lateral hypothalamus to the intermediolateral cell column of the upper thoracic spinal cord. The fourth component is the preganglionic and postganglionic sympathetic system arising from the upper thoracic cord to innervate the superior cervical ganglion which, in turn, innervates the pineal gland. No direct neural control of the pineal gland has been demonstrated in birds.