The pretectum mediates rapid eye movement sleep regulation by light

A variety of sensory stimuli (e.g., visual, auditory, and thermal) are know n to induce rapid eye movement (REM) sleep in mammals. Studies have examine d the induction of REM sleep in albino rats by light-to-dark transitions, a phenomenon referred to as REM sleep triggering. Recent research has demons trated that aspiration lesions of the superior colliculus (SC) and pretecta l area attenuated REM sleep triggering. To define more specifically the are a or areas involved in mediating REM sleep responses to changes in illumina tion, fiber-sparing neurotoxic lesions were made to the pretectum (PT) or t he SC. Lesions of the PT attenuated REM sleep triggering, whereas lesions o f the SC did not. Thus, the role of the PT may be expanded to include the r egulation of REM sleep in response to photic stimulation in albino rats. Th ese findings provide a paradigm in which to study mechanisms of REM sleep g eneration and the effects of light on behavioral state.