Structure of the brain

The brain is a complex and fascinating organ, it carries out complicated tasks and deals with lots of information from the surroundings. It perceives sensations, alerts us about danger and learns all the time. It prioritises, filters, plans and coordinates. It registers, recalls, analyses and concludes!

The outer layer of the brain is called the Cortex and this has areas for specific tasks. There is a sensory area (deals with incoming sensations), a motor area (deals with movements and actions), a speech area and many other specialist areas. A particular area of the brain called the prefrontal cortex (PFC) is particularly well developed and enlarged in humans. Located at the front end of the brain, the PFC is the centre for performing executive function and complex tasks. It also plays a role in inhibiting impulsive action and moderating social behaviour.

The lower extension of the brain is called the brainstem. This has 3 main structures - the midbrain, pons and medulla. The midbrain in involved in regulating important functions including heart rate, blood pressure and breathing.

The brainstem leads to the spinal cord which travels through the bony protection offered by the spine. The spinal cord carries messages between the body and the brain. There are powerful nerve fibres that do this function within a fraction of a second. Sometimes the body needs to respond instantly and automatically, for instance when we touch a hot object. This automatic function is performed at a local level within the spinal cord and called reflex action.

Another important structure in the brain is the thalamus. It functions as the relay centre for sensations reaching the brain. It has connections with other parts of the brain.

The building blocks of the brain and spinal cord are nerve cells called neurons. They carry messages in the form of electrical impulses. These messages include sensory information such as touch, temperature, pain and pressure. They also include information to muscles to make a particular movement.

Understanding the structure and function of the brain helps clinicians to make sense of a symptom. Disorders affecting the brain can be due to a localised problem (tumour) or a systemic problem (hypertension). Conditions affecting the brain structure are called organic disorders and there is evidence of tissue damage. Sometime the brain structure is preserved but the messages are not transmitted properly, this is referred to as a functional neurological disorder.