The structure of the brain and how it affects behaviour
Ψ The brain is a complex structure that controls everything about us, from our reflex
actions and movements to our thoughts and emotions.
Ψ There are more than 80 billion neurons in the brain alone.
Ψ The brain has been split into separate areas for studying. The outer layer is known as the
cortex, a deeply folded surface that covers four ‘lobes’ or sections (frontal, temporal,
parietal, and occipital). See figure 1.
Ψ Psychologists are interested in how the different areas of the brain and their particular
functions might affect our behaviour. Research into the link between the brain and the
body dates right back to the time of Philosopher and Scientist, Rene Descartes
Ψ Descartes argued that human beings are made up of 2 parts- the ‘body’ and the ‘mind’. He
assumed that the ‘mind’ could influence the ‘body’ via the pineal gland. Can you give an
example of when your mind has affected your body?
Ψ Later Philosophers and Psychologists went on to suggest that this influence also works
the other way; the body will also affect the mind, and therefore our behaviour.
Ψ Another early example comes from the work of Paul Broca (1824-1880), who showed that
a small area of the brain (now known as Broca’s area) is responsible for the production of
speech. Damaging this area means that the person can understand language, but they
cannot speak it.
Ψ The Hypothalamus is another important area as it links the nervous system to the
hormonal system. It is a regulatory system which controls the four Fs of life… Fighting,
Fleeing, Feeding, and Mating. See figure 2.
Ψ The Hippocampus is located in the temporal lobe and is
involved in long-term memory and learning.
This idea that specific areas of the brain are related to specific functions is known as
localisation. Functions are localised to particular parts of the brain.
What happens when the brain is altered in some way?
One way of seeing how behaviour and functions are localised is to look at case studies of
people who have suffered some kind of brain damage.
Example: Phineas Gage (1848)… Outline the case below:
We can use the idea of localisation to explain what had happened…
Draw the path of the rod onto the picture.
It is important to remember that not all of the brain’s functions are localised in this way.
Memory, for example is extremely complex, and research has so far not found a specific
section of the brain where memories may be stored.
Ψ The brain is not only split into four sections, it also has two hemispheres or halves, the
left and the right. The right hemisphere controls the left side of your body and the left
side of the brain controls the right side. The corpus callosum is the bundle of nerves in
the middle, which allows the two halves to communicate.
Left brain activities include:
Right brain activities include:
How might this assumption (the importance of the brain’s structure) explain memory loss?
What might be happening in the brain? (4)
Extension: Outline this assumption as an explanation of human behaviour. Why are
psychologists interested in looking at the brain? (4)