[The basal forebrain. Neuroanato-physiology and neurologic applications]

The Basal Forebrain region comprises the heterogeneous set of telencephalic structures on the medial and ventral aspects of the cerebral hemisphere. Basal Forebrain structures include the septal areas, olfactory tubercule, substantia innominata, and parts of the amygdala. The basal forebrain region is the site of a system of cholinergic neurons projecting to the entire cortical surface. The Basal Forebrain is a site of convergence of sleep and thermoregulatory functions. Portions of the basal forebrain play prominent roles in the control of the body temperature. The medial preoptic/anterior hypothalamic areas have both thermosensiting and thermointegrating functions. Cholinergic neurons intrinsic to the Basal Forebrain play a fundamental role in sleep onset and maintenance. Neurons of the nucleus basalis of Meynert undergo a profound degeneration in patients with Alzheimer's disease and provide a pathological substrate of the cholinergic deficiency in their brain. Behavior changes and amnesic syndrome may complicate surgery for ruptured anterior communicating artery aneurysms. Disruption of the blood supply through the perforating branches of the anterior communicating artery may probably cause the amnesic syndrome.