BIOLOGICAL PSYCHOLOGY NOTES
(3.1.1) The Central Nervous System
Evaluate the role of the central nervous system (CNS) and neurotransmitters in
explaining human behaviour.
AO1 - Damage in the ventromedial prefrontal cortex leads to impairments in behavioural
control and decision making.
AO3 - Raine et al. (1997) found NGRIs had lower activity in prefrontal regions, supporting
research linking damage to the PFC and aggressive behaviour.
AO1 – Amygdala is known as the emotional centre, and lower metabolic activity or an
amygdala with a smaller volume is linked to less emotional control and hence aggression
AO3 – Pardini et al found that lower amygdala volume is linked to aggressive behaviour in
men
AO1 - Low serotonin has been linked to aggression, assault, arson, murder, and child
beating.
AO3 - Research linking neurotransmitters such as serotonin to aggressive behaviour in
humans is correlational so other factors may contribute to aggression.
AO1 - Recreational drugs such as heroin stimulate dopamine which is rewarding and so can
lead to repeated use and could progress to addiction.
AO3 - Olds and Milner (1954) found that when stimulating areas of the dopamine pathway
(e.g. septal regions) rats would continue to press a lever due to the rewarding effects of the
stimulation.
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
Neurons
Information is transmitted through electrical and Chemical Signals. These signals
between neurons occur via neurotransmitters diffusing across synapses (gaps),
forming specialized connections with other nerve or muscle cells.
The sensory neurone transmits impulses from the receptor to the CNS. The motor
neurone transmits impulses from the CNS to the effector
Relay neurons pass the impulse from the sensory neurons to the motor neurons
Relay neurons are found in the spinal cord or brain
The effector can be a muscle or a gland; the role of the effector is to carry out the
response
Impulses can travel only in one direction
Structure:
,Dendrite- receives signals from other neurons or
receptors
Myelin sheath- insulates (protects the axon). Allows
nerve impulses to transmit more rapidly along axon
Cell body- contains the nucleus and controls the
neuron
Axon- carries impulses away from the cell body down
the neuron
Axon terminal- end of axon
Terminal buttons- point at which axon terminals
pass nerve impulses from the cell body to the part that they control or activate
Neurotransmitters:
Neurotransmitters are chemical messengers that act between the neurons in the
brain.
They can either enable or inhibit an action potential from being sent.
They are released into the gap and taken up by the receptors of a past Synaptic
neuron.
This causes a message to be sent from one neuron to the next.
Types of neurotransmitters:
Acetylcholine: generally excitatory. involved in muscle contraction,
particularly in voluntary movement. important role in memory,
particularly in encoding memories. Alzheimer's disease has been associated with
deficient acetylcholine and some treatments target this by trying to stop the
breakdown of acetylcholine.
Dopamine: implicated heavily in motor control. For example, L-dopa, a drug
commonly used to treat Parkinson's disease, a degenerative disorder in which the
person loses the ability to control their body, involves increasing the amount of
dopamine
Serotonin: Mood regulator, aids digestion and sleeping. Carries messages
between nerve signals. neurotransmitter with widespread inhibitory effects on
transmission between neurons in the brain – it slows down and dampens neuronal
activity. Normal levels of serotonin associated with a reasonable degree of
behavioural self-control. Decreased serotonin may well disturb this link, reducing
self-control and leading to more impulsive behaviours including aggression
GABA: main function is to reduce or 'inhibit' other neurons by binding to receptors.
Abdou et al. (2006) researched the effects of directly administrating GABA to 13
participants in a stressful situation. They found that administration of GABA reduced
stress as compared to a placebo. This suggests that the natural function of GABA may
be as a stress reducer.
Glutamate: glutamate is the primary 'excitatory' neuron in the CNS. For example,
drugs that increase the amount of glutamate are stimulants. As such, both GABA and
glutamate balance to control the level of excitation in the brain. Too much
excitement is toxic to neurons and is involved in damage following brain injury.
Epinephrine/Adrenaline Epinephrine, more commonly known as adrenaline, has
an important role in the stress response. Adrenaline produces changes in heart
rate, breathing and muscle tension, among other changes that are designed to cope
with physical stressors. these changes occur even when we need to deal with non-
physical demands such as exams. It boosts our metabolism, focuses our attention,
activates our ‘fight or flight’, causing our heart to beat faster and increases blood flow
to brain and muscles.
, Epinephrine does have other beneficial effects such as increasing our alertness and
wakefulness. This is also part of the stress response, so that a person is aware of and
able to quickly process their environment.
Synaptic Transmission:
An electrical impulse travels along the pre-synaptic neuron. The impulse reaches the synaptic
vesicles to release a neurotransmitter. These diffuse across the synaptic gap and attach to
receptors on the post synaptic neuron.
(3.1.2) Recreational Drugs
AO1 - Recreational drugs are those that are used for personal enjoyment. Such drugs include
caffeine, nicotine, alcohol, cannabis, amphetamines, LSD, cocaine and heroin, but there are
others. By investigating the effect of drugs on the nervous system, we now understand that
they change the way they increase or decrease neurotransmitters at the synaptic gap.
AO3 – Application - Understanding how drugs work on a neural level can help understand
addiction and possible biological solutions to addiction and withdrawal. Therefore we can
develop treatment to understand how addiction occurs, heroin addiction.
AO1 - One pathway important to understanding the effects of drugs on the brain is called the
reward pathway which involves several parts of the brain, including the including
hippocampus and the prefrontal cortex. When activated by a rewarding stimulus (e.g.
cocaine), the reward pathway creates the experience of pleasure, and this encourages the
behavior to be repeated to recreate the reward. Most psychoactive drugs of addiction work
on the limbic system.
AO3 - Individual differences, Makes it difficult to generalize effect of drugs as there may
be different factors that affect the way in which the brain reacts to drugs
AO1 - Heroine/cocaine increases the amount of dopamine in the reward pathways by
boosting the activation of dopamine synapses, causing an intensely pleasurable experience or
feeling of euphoria. However, this causes the brain to produce less dopamine (down
regulation), so when the drug wears off the person now has less dopamine than they would
have for normal brain functioning. This causes an unpleasant experience ( dysphoria).
AO3 - Hard to measure, There is a complexity in how transmission works in the brain that is
hard to measure. Cannabis limits hippocampal activity, but also leads to more dopamine
activity. Neurotransmitters also work in several pathways within the brain. Therefore hard to
measure as drugs affect many parts of the brain. Difficult to be 100%
AO1 - Repeated use occurs to compensate for the lack of dopamine produced by the brain
and so leads to addiction. Gradually more of the drug needs to be taken to have the same
effects.
AO3 - Research support - There is a lot of evidence supporting the arguments of drug
effects on the brain. Olds & Milner (1954) found when stimulating the reward pathway,
rats would keep pressing the lever due to its stimulating effects. However . . . This study
was completed on rats, and therefore may not be applicable to the human population.
Modes of Action:
Alcohol: Has a depressant effect on the nervous system by increasing the action of GABA (an
inhibitory neurotransmitter) and serotonin
Cannabis: Inhibitory effects on release of a variety of neurotransmitters from CNS neuron
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