A Circadian Pacemaker for Visual Sensitivity?a

Abstract
Visual signal detectability oscillates as a circadian rhythm, capable of free-running in constant conditions, and entrainment by external lighting schedules. These functions persist after lesioning of the suprachiasmatic nucleus (SCN), implicating a separate pacemaker for visual sensitivity. Its locus, physiology, and mode of interaction with the SCN have yet to be established.