synapses to specific receptor sites. Low levels of neurotransmitters at
synapses, have been found to cause low mood and depression. The re-
uptake of the neurotransmitter into the synapse causes the
neurotransmitter to become inactive. This means the level of the
chemical messenger at the synapse is lowered, causing low mood. Anti-
depressants such as Prozac act as re-uptake inhibitors; blocking re-uptake
and so increasing the amount of neurotransmitter at the synapse. It is also
believed by biologists that depression may be an inherited condition
passed down in the genes. However traumatic events are also known to
affect the nervous system and can cause these biological differences. In
some cases it may be to do with inheritance/biology, but it can also be to
do with people being exposed to certain levels of stress, traumatic events
and differing life experiences. Biology doesn’t explain why anti-
depressants work for some people and not others. Treatment often
involves dealing with biology and psychology through means of anti-
depressants and therapy.
Pleasure drugs such as alcohol, heroin and nicotine can also affect
mood and behaviour. They all affect the nervous system and activity
levels at the synapses which is known to affect mood. Alcoholics tend to
have lower levels of the neurotransmitter serotonin in their central
nervous system and alcohol temporarily increases these levels, which can
cause risk taking behaviour, make the person more confident and also
cause over anxiety. The low level of serotonin in alcoholics and the
‘high’ they then experience may be why they become addicted to this
drug-like substance. This is very similar to drugs such as cocaine.
Cocaine “blocks the re-uptake of dopamine and thereby increases the
amount of dopamine at synapses.” (Mapping Psychology 1, p258). After
taking the drug; users describe a period of euphoria, reflecting the
increase in levels of the neurotransmitter at the synapses. When the levels
of neurotransmitter at the synapse decreases rapidly it then creates a
feeling of dysphoria in the user causing low mood. This shows how
certain drugs can in effect alter the biology of our bodies, to affect mood
and behaviour.
Studies on the brain have been carried out to look at how the brain
affects behaviour, the main example being the study of brain damage
(lesion). Research has found that damage to particular areas of the brain
can affect personality and the behaviour exhibited. Phineas Gage has
been a major example of how personality can be changed by lesion. In
1848 he was involved in an accident and a tamping iron passed through
his brain. He survived the accident, but with severe damage to his frontal
lobes. The only changes observed outwardly where in his personality,
where he became stubborn, egocentric and rude; rather unlike how he
was previous to the accident. (Mapping Psychology 1, p266) This seems
to show that damage to the frontal lobes affects characteristics displayed.
However it is difficult for biologists to define which specific areas of the
brain affect personality because brain lesion in different people always
affects slightly different parts of the brain.
PET scans can show the levels of activity within different areas of the
brain and scientists have looked at comparing the brain activity of violent
criminals against that of non-offenders. The participants carry out
different tasks while brain activity is recorded. It has been found that
violent criminals have less activity in the areas of the brain which are
thought to help inhibit actions. This seems to support the argument that
behaviour is linked to biology, however it is unlikely to explain all
criminal behaviour and crimes.
Hormones are another example of how biology can affect
behaviour and mood. Hormones are ‘chemical messengers which are
released into the blood stream and carried to a receptor site elsewhere in
the body. Hormones which affect the nervous system, can affect mood
and behaviour. High levels of the hormone testosterone can produce
aggression, anti-social behaviour, domination and increased sex drive; in
humans and animals. Yet the environment can also affect hormone levels
e.g. Stress and anxiety can influence hormone levels, which then in turn
can alter behaviour. So biology can affect how we react in certain
situations, but in turn certain situations can alter our biology which
affects how we behave.
Another way of how the environment affects behaviour is the example of
homeostasis and temperature. Homeostasis is the body’s way of
maintaining a constant internal environment. When the external
environment becomes too hot the body sweats and makes blood vessels
close to the skin surface dilate to loose heat. However not all animals are
able to regulate their body temperature so when they get too hot, their
bodies rely on their behaviour to help them cool off e.g. finding shade
under a rock. The external environment affects their behaviour and
determines their actions.
Therefore it seems that biology does offer a significant contribution
to the understanding of behaviour, however other factors also need to be
considered such as social context and the environment. In this essay I
have given examples to show how biology can be significant in affecting
behaviour, but how it is not the only factor. The contribution
that biology offers is likely to change over time, as scientific and
psychological knowledge and understanding increases. As we learn more
about the biology of the brain, it is likely biology will become more and
more relevant, yet it is unlikely it will ever explain all situations.
(1098 words)
References:
Mapping Psychology 1, Exploring Psychology, The Open University, 2002, Dorothy Meill, Ann Phoenix and Kerry Thomas
