The prefrontal cortex (PFC) is reciprocally connected to numerous subcortical arousal nuclei, including the serotonergic dorsal raphe (DR), noradrenergic locus coeruleus (LC), cholinergic system of the basal forebrain (BFCS), and dopaminergic ventral tegmental area (VTA). Thus, much like the dorsolateral prefrontal cortex is involved in recurrent networks across the cortex that are important for content of consciousness, the medial prefrontal cortex is involved in recurrent networks with subcortical regions that are important for the level of consciousness. Modified from [18].