The Cerebral Cortex: Functional Areas

All 9 Terms & Definitions

Primary motor cortex (M1)

A strip of cortex on the precentral gyrus (just anterior to the central sulcus) that controls voluntary movement. Neurons in M1 project directly to motor neurons in the spinal cord via the corticospinal (pyramidal) tract. The body is somatotopically mapped — the motor homunculus — with disproportionately large representations for the hands, face, and lips reflecting their fine motor control demands.

Primary somatosensory cortex (S1)

Located on the postcentral gyrus (just posterior to the central sulcus, Brodmann areas 1, 2, 3), S1 receives tactile, proprioceptive, and temperature information from the body via the thalamus. Like M1, it contains a somatotopic map (the sensory homunculus). Areas with high receptor density and fine discriminative ability (fingertips, lips, tongue) have disproportionately large cortical representations.

Primary visual cortex (V1)

Located in the medial occipital lobe (Brodmann area 17, striate cortex), V1 is the first cortical region to process visual information arriving from the retina via the lateral geniculate nucleus of the thalamus. V1 contains a retinotopic map — a systematic representation of visual space. It is organised in columns responsive to orientation, ocular dominance, and spatial frequency. V1 damage causes blindness in the corresponding part of the visual field.

Primary auditory cortex (A1)

Located in the superior temporal plane (Heschl's gyrus, Brodmann areas 41–42), A1 receives auditory input from the medial geniculate nucleus of the thalamus. It is tonotopically organised — different frequencies are processed in different regions. In most people, A1 is larger on the left (planum temporale asymmetry), which relates to left hemisphere dominance for language.

Broca's area

Located in the left inferior frontal gyrus (Brodmann areas 44–45, pars triangularis and pars opercularis). Critical for speech production and syntactic processing. Damage produces Broca's (expressive) aphasia: effortful, non-fluent speech with preserved comprehension. Named after Paul Broca, who linked this region to speech loss in 1861. Modern neuroimaging shows Broca's area is part of a broader network for language, not a simple 'speech centre'.

Wernicke's area

Located in the left posterior superior temporal gyrus (Brodmann area 22). Critical for language comprehension. Damage produces Wernicke's (receptive) aphasia: fluent but meaningless speech (word salad), severely impaired comprehension. Named after Carl Wernicke, who described the syndrome in 1874. The arcuate fasciculus — a white matter tract — connects Broca's and Wernicke's areas; damage causes conduction aphasia (impaired repetition with preserved fluency and comprehension).

Prefrontal cortex (PFC)

The most anterior portion of the frontal lobe, comprising the lateral, medial, and orbitofrontal PFC. Associated with executive functions: planning, working memory, cognitive flexibility, inhibition of impulses, and decision-making. Also involved in personality, social cognition, and emotional regulation. The PFC is the last cortical region to fully myelinate (not until the mid-20s), which partly explains adolescent impulsivity and risk-taking.

Parietal association cortex

The posterior parietal cortex (Brodmann areas 5, 7, 39, 40) integrates spatial, somatosensory, and visual information to construct a representation of the body in space and guide attention and action. Damage to the right posterior parietal cortex causes hemispatial neglect (ignoring the left side of space). The angular gyrus (area 39) and supramarginal gyrus (area 40) are involved in reading, mathematical cognition, and tool use.

Default mode network (DMN)

A set of cortical regions — including the medial PFC, posterior cingulate cortex, and angular gyrus — that are most active during rest, mind-wandering, self-referential thought, and episodic memory retrieval. Discovered via the observation that these regions show consistent deactivation during externally-directed tasks. The DMN is altered in Alzheimer's disease, depression, and schizophrenia. It is thought to support self-modelling and simulation of past and future events.