BRS

Chapter 13 Diencephalon: Thalamus and Hypothalamus

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■ includes two major nuclei: 1. Lateral preoptic nucleus

■ the anterior telencephalic portion. 2. Lateral hypothalamic nucleus (Figure 13.4) ■ when stimulated, induces eating. ■ lesions cause anorexia and starvation.

B. Medial hypothalamic area (Figure 13.5) ■ includes the periventricular area that borders the third ventricle. ■ divided into four regions, from anterior to posterior: 1. Preoptic region ■ the anterior telencephalic portion.

Thalamus Mammillothalamic tract Dorsal hypothalamic area Dorsomedial nucleus Lateral hypothalamic area Ventromedial nucleus Supraoptic nucleus

L

V

L

V

F X

F X

MD

MD

P

V

O

T

Lesions (black) in ventromedial nuclei

Lesions (black) in extreme lateral part of hypothalamus

Voracious appetite (and rage)

Loss of appetite

Third ventricle

VL

F X

Medial nuclei Intralaminar nuclei Of thalamus Lateral nuclei

MD

Reticular nucleus of thalamus

VP

Mammillothalamic tract

Stimulation of this region (dorsomedial nucleus) or Destruction of this region (ventromedial nucleus)

Internal capsule

Dorsal hypothalamic area

Third ventricle Fornix (column) Lateral nucleus Arcuate nucleus Median eminence

Produces

Rage

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FIGURE 13.4. Coronal section through the hypothalamus at the level of the dorsomedial, ventromedial, and lateral hypo thalamic nuclei. The column of the fornix separates the medial from the lateral hypothalamic areas. FX, fornix; MD, medial dorsal nucleus of thalamus; OT, optic tract; VL, ventral lateral nucleus of thalamus; VP, ventral posterior nucleus of thalamus.