forebrain

Meaning: The forebrain (prosencephalon) is the largest division of the brain and supports higher cognition, emotion, memory, and regulation of the internal environment. It develops into the telencephalon (cerebral cortex, basal ganglia, and limbic structures such as the amygdala and hippocampus) and the diencephalon (thalamus and hypothalamus). Textbooks group the subcortical parts slightly differently, but all of these structures are forebrain.

On the MCAT: Expect function-to-structure matching and lesion reasoning. The thalamus relays most sensory input to the cortex (smell is the usual exception). The hypothalamus regulates hunger, thirst, body temperature, and hormone release through the pituitary. The amygdala is tied to fear and aggression. The hippocampus is needed to form new explicit memories, so damage causes anterograde amnesia. The frontal lobe handles planning, judgment, and motor output. The parietal lobe handles touch, the temporal lobe hearing and language comprehension, and the occipital lobe vision.

Common confusion: Students place the cerebellum, pons, or medulla in the forebrain. They are hindbrain structures (the cerebellum for balance and coordination; the pons and medulla for breathing and heart rate). The midbrain handles reflexive orienting to sights and sounds. Also keep thalamus (relay) and hypothalamus (homeostasis) distinct.