Hypothalamus - definition
group of nuclei that lies just below the thalamus. The hypothalamus is crucial in the maintenance of homeostasis, as well as reproductive functions, fight-or-flight reactions, feeding, and sleep.
Learn more:
2-Minute Neuroscience: Hypothalamus & Pituitary Gland
2-Minute Neuroscience: HPA Axis
The hypothalamus is colored green in the image above.