The ventromedial nucleus (sometimes referred to as the ventromedial hypothalamus or VMH) is a nucleus of the hypothalamus

Hypothalamus

The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...

.

Division

It has four subdivisions:

• anterior (VMHa)
• dorsomedial (VMHdm)
• ventrolateral (VMHvl)
• central (VMHc).

These subdivisions differ anatomically, neurochemically, and behaviorally.

Function

The ventromedial nucleus (VMN) is most commonly associated with satiety. Early studies showed that VMN lesions caused over-eating and obesity in rats. However, the interpretation of these experiments has since been discredited, as the blunt method of electrolytic lesioning destroyed not only the VMN cell bodies themselves, but also numerous fibre tracts passing through this region of the hypothalamus. In particular, it seems the over-eating was due, at least in part, to disruption of axons between the arcuate nucleus and other hypothalamic and brainstem nuclei, rather than directly mediated by the VMN.

VMH is also important in 'playing' behaviour seen in mammals. Lesions to VMH along with the hippocampus, amygdala, the cerebellum and the lateral hypothalamus will all reduce play behaviour.

The VMHdm has a role in the male vocalizations and scent marking behaviors.

The VMHvl plays a role in sexual behaviors in females (lordosis

Lordosis behavior

Lordosis behavior, or mammalian lordosis, is a sexual response in mammals, such as mice and cats, that consists of a ventral arching of the spine. During lordosis, the spine curves so that the apex points in the ventral direction. That is, the spine arches inward toward the abdomen.Lordosis aids in...

), thus stimulating their sexual arousal.

External links

• Diagram of Ventromedial motor tract at lemoyne.edu
• New Scientist: Seat of female libido revealed (June 26, 2006)