Brain Structure and Function

The brain is not one uniform mass carrying out a single job. It contains different regions that are particularly important for different functions. The three regions required here are the cerebral cortex, the cerebellum and the brain stem.

The cerebral cortex: higher mental functions

The cerebral cortex is the highly folded outer layer of the brain. It is divided into two hemispheres. Its folding allows a large amount of cortex to fit within the skull.

The cortex is involved in higher-level functions, including:

• intelligence — reasoning, learning and solving problems;
• memory — storing and recalling information;
• language — understanding and producing communication;
• consciousness — awareness of oneself and the surroundings.

It is also involved in conscious thought. These functions are connected: using language, for example, can involve memory, understanding and deliberate thought rather than just one completely independent process.

The cerebellum: controlled, co-ordinated movement

The cerebellum is involved in conscious movement and muscular activity. It co-ordinates the actions of muscles so that movements are controlled and smooth, and it helps maintain balance.

Consider reaching for a cup. The movement is conscious, but many muscles must contract by appropriate amounts and in the correct sequence. The cerebellum helps co-ordinate this activity. Its role is therefore more specific than simply saying that it “controls the body”: it is particularly important in balance and the co-ordination of movement.

The brain stem: maintaining vital automatic activity

The brain stem, which includes the medulla, regulates unconscious activities such as heart rate and breathing rate. These processes must continue even when a person is asleep or not deliberately thinking about them.

Regulation means that the rates can be adjusted as the body's needs change. During exercise, for example, working muscles require increased delivery of oxygen and faster removal of carbon dioxide. Heart rate and breathing rate rise without the person having to control every heartbeat or breath consciously.

Connecting each structure with its function

A useful way to distinguish the regions is by the kind of control involved:

• the cerebral cortex supports higher mental activity and conscious awareness;
• the cerebellum co-ordinates balance and conscious movement;
• the brain stem regulates vital, normally unconscious activities.

These are specialised regions within one interconnected brain, not three separate control systems. Their activities contribute together to an organised response—for instance, consciously deciding to move involves the cortex, while the cerebellum helps co-ordinate that movement and the brain stem continues regulating heart and breathing rates.

This content is specified for separate science only in OCR Biology B.