AP PSYCHOLOGY

Detailed explanation-1: -The ventrolateral preoptic (VLPO) nucleus in the anterior hypothalamus is the major area of the brain that controls sleep induction and maintenance. Its major neurotransmitter is GABA, and during the awake state, the GABA release from the VLPO nucleus is inhibited by norepinephrine (NE) from the locus ceruleus.

Detailed explanation-2: -Lesions in the region containing scattered VLPO neurons medial or dorsal to the cell cluster caused smaller changes in NREM sleep time (24.5 or 15%, respectively) but were more closely associated with loss of REM sleep (r = 0.74; p < 0.01). The insomnia caused by bilateral VLPO lesions persisted for at least 3 weeks.

Detailed explanation-3: -Most of the VLPO neurons are sleep-promoting neurons, which co-express -aminobutyric acid (GABA) and galanin, while TMN neurons express histamine (HA), a key wake-promoting neurotransmitter.

Detailed explanation-4: -The ventrolateral preoptic nucleus (VLPO) is a group of sleep-active neurons that has been identified in the hypothalamus of rats and is thought to inhibit the major ascending monoaminergic arousal systems during sleep; lesions of the VLPO cause insomnia.