The Brain (A2 only)

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The Brain

The brain can be split into different areas which all perform different functions specific to their location.

The two hemispheres

The longitudinal fissure is the deep groove that separates the brain into two halves or hemispheres: the left hemisphere and the right hemisphere.
There is evidence that each hemisphere has a specialised function - referred to as lateralisation.
- For example, we know that the left hemisphere controls the right half of the body and vice-versa.
The two hemispheres are connected by the corpus callosum, which allows the two hemispheres to communicate with each other.

Forebrain

The forebrain contains the cerebral cortex and a number of other structures that lie beneath the cortex (called subcortical structures): thalamus, hypothalamus, pituitary gland, and the limbic system.
- The cerebral cortex (the outer surface of the brain) is associated with higher level processes such as consciousness, thought, emotion, reasoning, language, and memory.
- The thalamus is a sensory relay for the brain. All of our senses, apart from smell, are routed through the thalamus before going onto other parts of the brain.

The limbic system

The limbic system is involved in processing emotion and memory.
The limbic system is made up of a number of different structures, but three of the most important are the hippocampus, the amygdala, and the hypothalamus.
The hippocampus is essential for learning and memory.
The amygdala is involved in our experience of emotion and in tying emotional meaning to our memories.
The hypothalamus regulates some homeostatic processes. It also provides an interface between the nervous system and the endocrine system and regulates sexual motivation and behaviour.

Hindbrain and Cerebellum

The brain can be split into different areas which all perform different functions specific to their location.

Hindbrain

The hindbrain is located at the back of the head and looks like an extension of the spinal cord.
It contains the medulla, pons, and cerebellum.
The medulla controls the automatic processes of the autonomic nervous system, such as breathing, blood pressure, and heart rate.
The pons connects the brain and spinal cord and is involved in regulating brain activity during sleep.
The medulla, pons, and midbrain together are known as the brainstem.

Cerebellum

The cerebellum receives messages from muscles, tendons, joints, and structures in our ear to control balance, coordination, movement, and motor skills.
The cerebellum is also thought to be an important area for processing some types of memories.
- In particular, procedural memory, or memory involved in learning and remembering how to perform tasks, is thought to be associated with the cerebellum.

Lesion studies

Much of what we know about the functions of different areas of the brain comes from lesion studies. These examine the changes in the behaviour and ability of people who have had damage to the brain.
For example, researchers study the behavioural changes caused by strokes to learn about the functions of specific brain areas.
A stroke is caused by an interruption of blood flow to a region in the brain. A stroke causes a loss of brain function in the affected region.
If the damage is in a small area, researchers can link any resulting behavioural changes to a specific area.

The Basal Ganglia

The basal ganglia are a set of brain areas located at the base of the forebrain. Together, they play an important role in the learning and control of our actions.

Location

The basal ganglia are located at the base of the forebrain.
They are close to and interconnected with the thalamus and the cerebral cortex.
The basal ganglia consist of several components. These include: striatum, substantia nigra, putamen and caudate nucleus.

Striatum

The striatum affects motivation and whether we find actions rewarding or not.

Substantia nigra

The substantia nigra, literally meaning ‘black substance’,
This area appears darker than surrounding brain tissue, and plays a role in reward seeking and addiction.