The Structure and Function of the Brain
Mapping the Brain: Structure and Function
The human brain is the most complex organ in the body. Psychologists divide the outer surface of the brain — the cerebral cortex — into regions to work out which parts control which behaviours, a principle called localisation of function. The cortex is split into four main lobes: frontal, temporal, parietal and occipital. A separate structure, the cerebellum, sits at the back and base of the brain. Each region has its own specialist job.
The brain’s four lobes and the cerebellum each have a distinct role: frontal (movement, planning, personality), temporal (hearing, language), parietal (touch and body senses), occipital (vision), and cerebellum (balance, coordinated movement).
The Frontal Lobe
The frontal lobe sits at the front of the brain, behind the forehead. It contains the motor cortex, which sends signals to the muscles to produce voluntary movement, such as reaching for a pen. The front-most part of the frontal lobe, the prefrontal cortex, is involved in planning ahead, making decisions and controlling impulses — it plays a large part in personality and self-control.
The Temporal Lobe
The temporal lobe is located at the side of the brain, roughly level with the ears. It contains the auditory cortex, which processes sound, and areas responsible for understanding spoken and written language. The temporal lobe also contributes to forming new long-term memories.
The Parietal Lobe
The parietal lobe lies just behind the frontal lobe, towards the top and back of the head. It contains the somatosensory cortex, which receives information about touch, temperature, pressure and pain from across the body. This lobe also helps the brain build a sense of where the body is in space.
The Occipital Lobe
The occipital lobe sits at the very back of the brain. It contains the visual cortex, which receives signals from the eyes and works out colour, shape, movement and depth. Almost all visual processing happens in this single lobe, even though what we “see” feels instant and effortless.
The Cerebellum
The cerebellum is a separate, cauliflower-shaped structure tucked underneath the occipital lobe, at the back and base of the brain. It fine-tunes movement, keeps the body balanced, and helps build smooth, automatic motor skills through repeated practice — such as learning to ride a bike or type without looking at the keys.
Localisation of function means specific mental abilities map onto specific brain regions rather than being spread evenly across the whole brain. Damage to one lobe tends to disrupt the specific ability linked to that lobe, while leaving other abilities intact.
Evidence for Localisation of Function
Psychologists have built up evidence for localisation of function from two main sources. Case studies of people with brain damage show that injury to a specific lobe produces a specific pattern of difficulty — damage near the occipital lobe disrupts vision, while leaving hearing and movement unaffected. Modern brain-scanning technology can also show which regions become more active during particular tasks, such as the occipital lobe lighting up when a person looks at a picture.
Although the cerebellum makes up only a small proportion of the brain’s overall volume, it is thought to contain a very large share of the brain’s total neurons, reflecting how much fine-detail coordination it manages. It works constantly in the background, comparing the movement the body intended to make with the movement that is actually happening, correcting small errors before we even notice them.
Damage to the cerebellum does not usually stop someone from moving altogether. Instead, movement becomes jerky, poorly timed and difficult to control — reaching for a cup might overshoot, or walking might become unsteady. This shows that the cerebellum’s job is refinement and timing, not simply switching movement on and off.
Localisation of function is a useful model, but real behaviour is rarely produced by just one lobe working alone. Understanding a sentence, for example, draws on the temporal lobe for recognising words and the frontal lobe for working out meaning and forming a response — the lobes work as a connected network rather than in isolation.
Evidence from brain injury also shows the brain can be flexible. After damage to one area, healthy regions sometimes adapt and partly take over lost functions, especially in younger patients. This flexibility, known as brain plasticity, suggests the strict view of fixed, unchanging localisation may be too simple on its own.