cortex

Meaning: In psychology the cortex is the cerebral cortex, a thin, folded layer of gray matter (neuron cell bodies) covering the cerebrum. Folding into gyri (ridges) and sulci (grooves) increases surface area. Each hemisphere has four lobes: frontal (voluntary movement through the motor cortex, planning and judgment through the prefrontal cortex), parietal (touch and body position through the somatosensory cortex), temporal (hearing, language comprehension, memory), and occipital (vision). Association areas combine information from several senses.

On the MCAT: Passages describe a lesion, stroke, or imaging study and ask which function is lost or active. Expect Broca's area (speech production, frontal lobe) versus Wernicke's area (comprehension, temporal lobe), both usually in the left hemisphere. Prefrontal damage that changes personality and impulse control (Phineas Gage) is another common case. In the motor and sensory homunculus, body parts needing fine control get more cortex. Each hemisphere mostly handles the opposite side of the body.

Common confusion: The cortex is not the whole brain. Structures beneath it, such as the thalamus, hippocampus, and amygdala, contribute to sensory relay, memory formation, and emotion, so those functions are not purely cortical. The cerebellum, not the cortex, fine-tunes coordination and balance.