|Brain: Basal forebrain|
The Basal Forebrain
|Latin||pars basalis telencephali|
The basal forebrain is a collection of structures located rostrally and ventrally to the striatum. It is considered to be the major cholinergic output of the central nervous system (CNS). It includes a group of structures that lie near the bottom of the front of the brain, including the nucleus accumbens, nucleus basalis, diagonal band of Broca, substantia innominata, and medial septal nuclei. These structures are important in the production of acetylcholine, which is then distributed widely throughout the brain.
Acetylcholine affects the ability of brain cells to transmit information to one another, and also encourages plasticity, or learning. Thus, damage to the basal forebrain can reduce the amount of acetylcholine in the brain and impair learning. This may be one reason why basal forebrain damage can result in memory impairments such as amnesia and confabulation. One common cause of basal forebrain damage is aneurysm of the anterior communicating artery.1 Research, conducted by investigators from Children's Hospital Boston and the University of Helsinki, ties together previous observations about sleep and finds that nitric oxide production in the basal forebrain is both necessary and sufficient to produce sleep.2
This structure is defined, in part, as the place where adenosine acts on A1 receptors of cholinergic neurons. This results in hyperpolarization of cholinergic neurons, which inhibits the release of acetylcholine. Acetylcholine is known to promote wakefulness in the basal forebrain. Inhibition of acetylcholine release in the basal forebrain by adenosine causes slow wave sleep.
The basal forebrain and adjacent areas are a focus for sleep research. Stimulating the basal forebrain gives rise to Ach release, which induces wakefulness and REM sleep.