HCRT and multiple system atrophy: Furthermore, patients with MSA are known to show impairment of the neural systems involved in the maintenance of the waking state, including the cholinergic neurons of the mesopontine tegmentum[8], serotonergic neurons of the rostral raphe[9], hypocretin/orexin neurons of the lateral hypothalamus[10], and putative wake-active dopaminergic neurons in the ventral periaqueductal gray matter[11].