Beyond the role in motor function, entopeduncular nucleus, a critical neural hub in psychiatric disorders and sleep regulation

The entopeduncular nucleus (EP) has traditionally been categorized as a primary motor output nucleus within the basal ganglia, homologous to the human globus pallidus internus (GPi). However, recent research suggests that its role is far broader, acting as a critical integrative hub that bridges limbic, associative, and motor circuitry. This review synthesizes mounting evidence that the EP is deeply involved in psychiatric disorders—such as depression, anxiety, addiction, and OCD—as well as the regulation of sleep and circadian rhythms.

The EP's versatility stems from its complex connectivity and neurochemical diversity. It receives input from the striatum and modulates downstream targets through GABAergic, glutamatergic, and neuromodulatory signaling. A central mechanism identified is the EP-lateral habenula (LHb) pathway, which functions as a key mediator of aversive processing and addiction-related behaviors. When this circuit is disrupted, it contributes to the negative emotional states observed in substance withdrawal. Furthermore, EP projections to the thalamus regulate thalamocortical gating; dysfunction here is linked to the cognitive and sensory processing deficits characteristic of schizophrenia and the compulsive behavioral patterns seen in OCD.

Beyond psychiatric regulation, the EP exerts significant control over sleep architecture. Evidence highlights that the endocannabinoid system within the EP, particularly through cannabinoid receptor 1 (CB1R), plays a vital role in promoting non-rapid eye movement (NREM) sleep. Moreover, specific neuronal subpopulations within the EP are active during REM sleep, suggesting a role in post-sleep mood regulation. These findings have sparked interest in neuromodulation techniques, such as deep brain stimulation (DBS). While DBS of the EP is an established intervention for motor symptoms in Parkinson's disease, its therapeutic potential for treatment-resistant depression and other neuropsychiatric conditions is an active, albeit early, area of clinical exploration.