Intro | Amygdala | Brainstem | Cerebellum | Cerebrum | Corpus Callosum | Reticular Formation | Hippocampus | Hypothalamus | Medulla | Pituitary Gland | Pons | Spinal Cord | Thalamus
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Part 3: Multiple-Choice Self-Test
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The Hypothalamus is a tiny structure located at the base of the forebrain below the thalamus. It is included in the Limbic System. This regulating structure underlies behavior that seeks to satisfy both our basic biological needs (such as hunger, thirst, temperature control) and survival reactions (the four "F's" - fighting, fleeing, feeding and sex drive). The hypothalamus exerts this control in part via its effects on the pituitary gland and the autonomic nervous system. Electrical stimulation of the lateral region of the hypothalamus in animals induces constant eating and excessive weight gain. More discussion of the hypothalamus can be found with Figure 12.
The medial forebrain bundle (a bundle of axons that passes though the hypothalamus) is rich in dopamine neurons that, when stimulated result in reinforcing or pleasurable feelings. The rewarding and pleasurable effects of some drugs such as the opiates (heroin and morphine) and stimulants (amphetamines and cocaine) many result from stimulation of this dopamine system.
The hypothalamus is divided into distinct nuclei that underlie its various, specific functions. For example, one of these nuclei appears to be distinctly different in appearance and function when comparing across sex. The medial preoptic area is two to three times larger in the human male than the female. This size difference occurs in response to higher levels of testosterone during the third and fourth months of pregnancy. The preoptic nucleus is responsible for regulation of body temperature. Shivering and sweating are the behaviors used to control extreme cold and heat, respectively.