What are the Functions of the Hypothalamus?

The hypothalamus acts as the ‘head ganglion’ of the autonomic nervous system. The basic drives of life – hunger, thirst and sex, originate in the hypothalamus. The hypothalamus is central to the maintenance of homeostasis.

The functions of the hypothalamus include:

(1) Autonomic control. Its anterior and medial parts (preoptic and supra-optic areas) control the parasympathetic activity, while the posterior and lateral parts of the hypothalamus regulate the sympathetic activity.

(2) Control of pituitary. The hypothalamus regulates the function of posterior lobe through the hypothalamo- hypophysial tract, and modulates the secretion of anterior lobe hormones through the hypothalamo-hypophysial portal system.

(3) Temperature regulation. The hypothalamus is the principal integrating center for thermoregulation, bringing about a balance between heat production and heat loss.

(4) Regulation of feeding behavior. The ventromedial nucleus acts as a satiety center, whereas the lateral nucleus serves as the feeding or hunger center.

(5) Regulation of sexual behavior. The tuberal region of hypothalamus maintains the basal secretion of gonadotropin releasing hormone (GnRH), and its connection with the preoptic area is essential for the cyclical surge of gonadotropin before ovulation.

(6) Emotional behavior. While emotions are mainly regulated by the limbic cortex, the physical adjuncts of emotions (palpitation, cutaneous flushing, piloerection, sweating etc.) are mediated by the hypothalamus through the autonomic nervous system. Stimulation of the ventromedial nucleus produces aggressive behavior and that of the lateral nucleus induces a flight response. The lateral hypothalamus close to the feeding center represents a ‘pleasure-center’, because electrical stimulation of this area encourages the animal to seek more of such stimulation. The medial hypothalamus seems to act as a ‘punishment center’, since the experimental animal avoids further stimulation.

(7) Circadian rhythm. The suprachiasmatic nucleus of hypothalamus is central to the maintenance of all circadian rhythms.

(8) Sleep and wakefulness. The anterior hypothalamus is considered to be a sleep facilitator center while the posterior hypothalamus acts as a waking center.