ABSTRACT
The importance of the hypocretin/orexin (hcrt/orx) system (1,2) in promoting wakefulness has been amply documented in mice, dogs and humans (3-6). The way by which the hcrt/orx system exerts its action is however still a matter of debate and has been our major subject of interest using an in vitro electrophysiological approach that followed essentially two lines. First, we studied the actions of hcrt/orx upon neurons that one could subdivide into three categories: those of the preoptic area associated with promoting sleep, those of major diencephalic structures associated with promoting wakefulness (basal forebrain, tuberomammillary nuclei and intralaminar thalamic nuclei) and finally those of the cerebral cortex. Second, we investigated the intrinsic properties of hcrt/orx neurons that could be relevant to their ability to promote wakefulness.
