(P1) biological psychology Flashcards
(121 cards)
1
Q
what is lateralisation
A
If we look at a human brain, or the brains of most other animals, we can see that there are two distinct halves, and that the organ is roughly symmetrical. In technical terms, there are two hemispheres in the human brain. ‘Lateralisation’ refers to the tendency of the different hemispheres of the brain to take care of slightly different functions. For example, the language areas are found in the left hemisphere in the majority of people.
The most basic manifestation of lateralisation is that, broadly, the left hemisphere corresponds to the functioning of the right side of the body and vice versa (this ‘crossover’ is sometimes called ‘contralateralisation’). If you tread on something sharp with your right foot, it is in your left hemisphere that the damage is registered and the sensation of pain is produced (to alert you to the fact that something bad has happened and to do something about it). Conversely, if you reach out with your left hand to pick something up, it is your right hemisphere which is sending out the signals to the muscles that cause your arm to move. If one hemisphere of the brain is damaged, then the first sign is often a change in the functioning of the opposite side of the body.
Lateralisation goes beyond sensing and moving the body. Many other psychological processes show some degree of lateralisation. For example, in 90% of right handed people, language processing (speaking and understanding the speech of others) is done by the left hemisphere of the brain. There is also evidence that, generally, the left hemisphere deals with information by breaking it down into simpler parts, whereas the right hemisphere prefers to process information in a holistic way. That said, the two hemispheres are in constant communication with each other through a ‘bridge’ between the two hemispheres called corpus callosum.
2
Q
what is localisation?
A
‘Localisation’ refers to the tendency of different areas within the brain to be responsible for different functions. In the outside layer of a mammal’s brain (the cerebral cortex) we can identify many different small areas that take care of different psychological processes. At the front of the cortex there are areas responsible for planning and problem solving. Further back we find areas responsible for moving and sensing the body. Around the sides we can identify areas that are important for memory, and, at the back, there are the areas that process visual information from the eyes.
3
Q
what is the nervous system?
A
The nervous system is a network of specialised cells capable of transmitting information around the body. It co-ordinates the behaviour of the organism.
4
Q
what is the central nervous system?
A
The central nervous system processes information. It consists of the brain and spinal cord.
5
Q
overview of neurons and neural transmission
A
The nervous system is made up of several types of cell. The most important type is the neuron. Neurons generate electrical signals called action potentials. These signals start at one end (the dendrites) and finish at the other (the terminals). A neuron generates action potentials all the time. The number of action potentials generated each second is called its firing rate.
Although all action potentials are identical, the neuron can vary its firing rate to be faster or slower. It does this in response to the signals it receives from other neurons that connect to it. In turn, the firing rate of the receiving neuron influences the firing rates of other neurons it is connected to.
6
Q
neuron
A
the main cell of the nervous system
7
Q
role/function of the neuron
A
the neuron’s role is to pass messages between other neurons using neurotransmitters to enable behaviour, thinking and emotions to be transmitted and to enable the working of the brain.
the electrical impulses travelling down the axon trigger the release of neurotransmitters from the terminal at the end of the axon.
the neurotransmitters are then released into the synaptic gap to be picked up by receptors on the dendrites of other neurons or to be re-uptaken for reuse. this is known as synaptic transmission.
8
Q
action potential
A
the electrical signals that are sent from the dendrites to the terminals of a neuron.
9
Q
dendrites
A
the tree-like structures that receive signals from other neurons.
10
Q
axon
A
the long, branching structure that transmits the action potential to the terminal, allowing neural signals to be sent over (potentially) long distances.
11
Q
terminal
A
the structure where action potentials finish, and chemical signals are sent to other neurons.
12
Q
myelin sheath
A
a fatty substance wrapped around the axons of some neurons. It allows action potentials to travel faster.
13
Q
ions
A
charged particles. The movement of ions allows the action potential to happen.
14
Q
firing rate
A
the frequency with which a neuron produces action potentials. A neuron’s firing rate increases or decreases in response to the signals it receives from other neurons at its dendrites
15
Q
role/function of neurotransmitters
A
role of neurotransmitters is to carry messages from one neuron to another.
- if the neurotransmitter released from the terminal of an axon is not taken up by the dendrites of an adjacent neuron, the message stops.
16
Q
process of neural transmission
A
The nervous system, which gives rise to and organises our thinking, emotion and behaviours, is a network of specialised cells called neurons. A neuron is specialised in two ways. First, it can transmit electro-chemical signals, called action potentials, from one end (its dendrites) to the other (its terminals). Second, it can form connections with other neurons. These connections are called synapses.
A neuron constantly transmits action potentials. Each action potential is the same as all the others, so a neuron cannot transmit action potentials of different strengths or speeds. However, a neuron can vary the frequency with which it transmits action potentials. This frequency is called the neuron’s firing rate. Variations in the firing rate are caused by chemical messages received at its synapses from other neurons (the upstream neurons). These messages may cause the neuron to increase or decrease its firing rate. As it varies its firing rate, the neuron can, in turn, influence the firing rates of all the neurons it sends messages to (the downstream neurons).
When a neuron is not transmitting an action potential it is ‘at resting potential’. During resting potential there is a difference in electrical charge between the inside and the outside of the neuron. The difference in charge is caused by there being different concentrations of ions (charged particles) on either side of the neuron’s cell membrane. The outside has a higher concentration of positive ions than the inside, so the membrane is polarised - there is a positive charge outside compared to the inside. Most of the time, the cell membrane is impermeable to these ions, so the difference in charge is maintained.
An action potential starts when the neuron is stimulated by chemical messages received from upstream neurons at its synapses. If enough stimulation occurs, the neuron opens tiny ion channels in its membrane. Because there is a higher concentration of positive ions outside the neuron, the opening of the ion channels causes positive ions to flood into the neuron by diffusion. Because of this influx of positive ions, the difference in charge across the cell membrane is reversed (depolarised) in that region. This local reversal of the charge across the cell membrane is the action potential.
As soon as the action potential has occurred in one area of the neural membrane, the membrane at the immediately adjacent site also becomes disturbed, and the ion channels open. This causes the membrane to depolarise and, through this process, the action potential propagates along the cell membrane in the direction of the terminal in a chain reaction, a bit like toppling dominoes. At the same time, where the membrane has been depolarised, the ion channels close, and tiny pumps start working, moving the ions back to where they started. While this is happening, another action potential cannot occur. This is called the refractory period.
Overall, the propagation of an action potential from the dendrites to the terminals is a bit like a ‘Mexican wave’ in a crowd at a sports event. People standing up and sitting down in a sequential way creates the appearance of a ‘wave’ in the crowd that travels around the stadium. What is important to appreciate is that the only movement that actually occurs is the people standing up and sitting down a moment later - but this creates the ‘wave’ that seems to move right around the crowd. By analogy, the people sitting down represent the neural membrane at the resting potential. The people standing up represent the depolarised portion of the neural membrane and the ‘wave’ represents the action potential as it propagates along the neuron.
Some neurons have a myelin sheath wrapped around their axon. The myelin is a fatty substance that prevents an action potential from propagating. However, there are little breaks in the myelin at regular intervals along the sheath. These are called the nodes of Ranvier. At each node, the neural membrane is exposed. This allows an action potential to ‘jump’ quickly from node to node in a process called saltatory conduction. Saltatory conduction speeds up the propagation of an action potential quite significantly, so a myelin sheath allows a neuron to send messages faster than an unmyelinated one. This is an advantage where axons have to stretch over long distances (e.g. in the arms and legs) so myelinated neurons are found more in the spinal cord and the peripheral nervous system than in the brain.
17
Q
draw the structure of a neuron
A
18
Q
explain the process of synaptic transmission
A
A synapse is the junction between two neurons. Neurons influence each others’ firing rates by sending chemical signals at their synapses. The action potentials reaching the terminals on the presynaptic neuron cause the release of a chemical called a neurotransmitter. The higher the firing rate, the more neurotransmitter is released. The neurotransmitter drifts across the synaptic gap and binds to receptors on the postsynaptic neuron. This causes its firing rate to change (either up or down).
Following release, neurotransmitter in the synaptic gap is broken down by enzymes or recycled by a reuptake pump. Some important neurotransmitters are dopamine, serotonin and GABA.
19
Q
synapse
A
junction between two neurons*
20
Q
synaptic transmission
(short definition)
A
the process in which one neuron signals to another neuron to increase or decrease its firing rate.
21
Q
presynaptic membrane
A
the end structure of a neuron, where action potentials stop, and chemical signals are sent out.
22
Q
postsynaptic membrane
A
the areas on a neuron’s dendrites, where chemical signals are received from other neurons.
23
Q
synaptic gap
A
the space between the presynaptic and postsynaptic membrane. It is filled with fluid.
24
Q
neurotransmitters
A
chemicals that convey a message from the presynaptic to the postsynaptic neuron.
25
**vesicles**
tiny ‘bubbles’ inside the presynaptic terminal where neurotransmitter is held before release.
26
**reuptake**
a process in which excess neurotransmitter it taken back into the presynaptic terminal and recycled.
27
evidence for neurotransmitters (link to schizophrenia/depression)
Abnormal levels of different neurotransmitters are implicated in a range of atypical behaviours. Having too much or too little of a particular neurotransmitter could cause activity to increase or decrease in the brain structures that used that neurotransmitter.
In clinical psychology, schizophrenia (a disorder in which a person experiences hallucinations and delusions) has been linked with excessive dopamine activity. Depression (a disorder where the person experiences low mood and negative thinking) has been linked with too little serotonin activity.
28
**hindbrain**
a set of brain structures at the top of the spinal cord, mainly dealing with survival functions like breathing, heartbeat and consciousness.
29
**midbrain**
a set of brain structures above the hindbrain, mainly responsible for movement and for homeostasis (keeping the internal environment stable).
30
**limbic system**
a set of brain structures linking the midbrain and the forebrain, mainly responsible for emotional responses including fear and anger. It plays an important role in aggression.
31
**forebrain**
a set of brain structures in the upper and outermost parts of the brain. It includes areas important for ‘higher’ mental functions like thinking, language and memory.
32
what is **brain scanning?**
Brain scanning refers to a set of technologies for producing images of the structure and functioning of the brain. Three important ones are CAT/CT, PET and fMRI. All of them generate cross-sectional images of the brain but they do so in different ways so they have different strengths and weaknesses. CAT scans are fast and cheap, but they only show brain structure, not activity. PET and fMRI show brain activity, but take longer and cost more than CAT scans.
A researcher wanting to investigate the brain needs to select the best technique to fulfil the aim of her study; there is no automatic ‘best’ technique to use. What turns out to be the best technique depends on what the research is trying to find out, who she is doing this with and under what conditions.
33
**brain scanning/imaging**
using technology to produce images of brain structure and/or activity without needing to open up the skull.
34
**CAT scan**
an imaging technology that uses X-rays to generate pictures of brain structure.
- x-rays
- greyscale image showing high level of detail of structures in the brain **(0.5mm spatial resolution)**
- temporal resolution: N/A as it DOES NOT show function/brain activity
- can image bone, soft tissue and blood vessels simultaneously
- CT scanner relatively cheap (£1 million for the scanner) and quick (5 mins)
35
**PET scan**
an imaging technology that generates images of brain activity by tracing the uptake of glucose in different brain areas.
- radioactive tracer is injected
- records brain activity
- non-invasive (nothing enters the body)
- **spatial resolution** 6mm (not very refined detail in images)
- PET has a temporal resolution of 5-15 mins (longer than fMRI)
- PET scanners are expensive (£2-3 million) and running costs are higher because you need facilities to make short-lived radioactive isotopes.
36
**fMRI scan**
an imaging technology that generates images of brain structure and activity by tracking the movement of water/blood in different brain areas.
- tracks brain activity
- response of brain tissues to a strong magnetic field
- **spatial resolution of 1.5mm**
- **temporal resolution** of 20 seconds
- very succeptible to motion-related artifacts (errors) as it is sensitive to movement, meaning images may blur.
- fMRI scanner costs £1.9 million and scan takes longer (30-40mins)
37
**spatial resolution**
how much fine detail is presented in the scan image. A scanner with a higher spatial resolution shows a more detailed image.
38
**temporal resolution**
how well the scanner tracks changes in brain activity over time. A scanner with a higher temporal resolution is more responsive to short-term changes in brain activity.
39
evidence for **brain scanning techniques**
**Raine et al. (1997)** used PET scans to compare murderers with ordinary people. They found that the murderers had different patterns of brain activity in the forebrain and the limbic system.
**Hirvonen et al. (2011)** used PET scans to show that long-term users of cannabinoid drugs show changes to the brain.
**Gazer et al. (2000)** used MRI scans to show that schizophrenia patients had reduced volumes of brain tissue compared to a comparison group.
**Carlsson et al. (2000)** used a range of studies, including brain imaging to show that schizophrenia is related to abnormalities in brain systems that use dopamine and glutamate as their main neurotransmitter.
40
what is biological psychology?
the study of the biology of behaviour. it focuses on the nervous system, hormones and genetics. biological psychology examines the relationship between the mind and body, neural mechanisms and the influence of heredity on behaviour.
41
what are the **basic assumptions** of biological psychology?
- thinking and behaviour can be explained in terms of biological factors (all thinking and behaviour is caused by the central nervous system, CNS).
- human genes have evolved over millions of years to adapt behaviour to the environment
- patterns of behaviour can be inherited, therefore, most behaviour will have an adaptive/evolutionary purpose.
42
why are brains studied in **biopsychology?**
the brain is the seat of consciousness. the brain is where our decisions originate and where processes that lead to our feelings and memories take place. it is where your self is located.
psychology is the study of the mind (the Greek word *psyche* means ‘mind’) but **neuropsychologists** are interested in the brain because it shapes the mind. we know that changes to the brain produces changes in mental state. this can be seen when people take drugs or suffer from brain damage (e.g. a stroke.)
43
how has brain imaging technology evolved?
brain research used to be limited to examining the dead brains of corpses. this was unhelpful because dead brains liquify within hours. however, since then the invention of **brain imaging technology** has revolutionised psychological understanding of the brain because now we can study live brains to understand thinking or remembering.
44
what **creatures** have a central nervous system (CNS)?
vertebrates.
this is a category that includes humans and all other mammals, reptiles, birds and fish but not (for example) insects.
45
what is the **peripheral nervous system (PNS)?**
as well as the CNS. you have other nerves in your body. this is the **peripheral nervous system (PNS)**, which stretches out from your brain and spinal cord into every other part of your body. the peripheral nervous system includes **sensory nerves**, which carry information back to the brain as sensations (the ‘five senses’) and **motor nerves** which carry messages from the brain, telling muscles to move and glands to release their hormones.
46
what are the two hemispheres of the brain linked by?
a bridge of nerve fibres called the **corpus callosum**. the corpus callous allows the left and right hemispheres to communicate with each other.
47
what is the **left hemisphere** of the brain responsible for?
the left hemisphere is responsible for linear thinking mode. this involves:
- right hand control
- writing
- language
- scientific skills
- mathematics
- lists
- logic
48
what is the **right hemisphere** of the brain responsible for?
the right hemisphere of the brain is responsible for holistic thinking mode. this includes:
- left hand control
- emotional expression
- spatial awareness
- music
- creativity
- imagination
- dimension
- whole picture things
49
cerebral cortex
humans have a complex outer layer called the **cortex**. the cortex handles a lot of ‘higher’ brain functions, such as conscious thought and interacting with the world around us. it is divided into a number of areas with different functions, the most important being the **four lobes**.
- cerebral cortex is only fully developed in humans
50
what are the 4 **lobes** in the brain?
**frontal lobe:** handles most of our conscious planning, especially an important part of it called the **pre-frontal cortex**
- behaviour
- intelligence
- memory
- movement
**temporal lobe:** handles most of our memory functions.
- behaviour
- memory
- speech
- hearing
- vision
**occipital lobe:** at the back of the brain, but it processes sight and our sense of ur environment.
**parietal lobe:** controls language, but also specialises in touch and directing bodily movements.
51
what is the **limbic system**
the limbic system handles memory but also raw appetites and desires- sleep, hunger, aggression and sex. it is thought to be the source of all of our basic emotions. this is the part of the brain we share with most other animals. a set of brain structures linking the midbrain and the forebrain, mainly responsible for emotional responses including fear and anger. It plays an important role in aggression.
it contains the:
- frontal lobe
- thalamus
- hippocampus
- amygdala
- hypothalamus
- offactory bulb
52
thalamus
sometimes called the brain’s ’switch board’, since it handles all the messages coming in from the brain and routes them to where they need to go.
53
amygdala
The amygdala is the shape of an almond. It is the brain's "emotion centre". It handles emotional responses to things, especially anger and fear. If it is working properly, we should only fear things that are dangerous. it is responsible for interpreting threat and provocation.
**Raine et al. (1997)** noticed that the amygdala in murderers functioned erratically; this suggests they might not have felt fear or aggression at appropriate times. Other studies on animals have shown that, when the amygdala is damaged, the animal stops showing fear of threatening stimuli.
54
hypothalamus
The hypothalamus is the shape and size of a pea. It regulates hunger, thirst, sexual arousal and sleep. Animals with damage to the hypothalamus have been known to lose all interest in food or else to start eating compulsively.
- also part of the **endocrine system**, it regulates hormone production in the body.
55
hippocampus
The hippocampus is shaped like a sea horse (it's name means "sea horse"). It is important for forming new memories: it is the brain's "memory factory". Damage to the hippocampus destroys the ability to form new long term memories. A famous example of someone with this problem was H.M. (Henry Molaison), whose hippocampus was removed during brain surgery. Schmolck et al. (2002) found that semantic long term memory was located outside the hippocampus, in the medial temporal lobe.
56
olfactory bulb
This brain structure processes smell. Its link to the limbic system explains how smells can trigger hunger (bacon frying) or sexual arousal (perfume) but also fear (as when animals pick up a threatening scent)
57
motor neurons
motor neurons receive messages from the CNS and generate movements.
58
sensory neurons
transmit information about the 5 senses (sight, sound, touch, taste, smell) from your sense organs to the rest of the brain
59
inter-neurons
inter neurons take messages between other neurons
60
describe the structure of a neuron
The neuron has a cell body with a **nucleus** in the middle. Round the outside of this are branch-like **dendrites** (the name comes from the Greek word for "tree") which pick up information from other cells and turn it into an electric signal. This electrical charge travels down the **axon**, which is the long "tail" of the cell, until it gets to the **axon terminals**, which look a bit like fingers. These terminals pass the information on to the dendrites of the next cell in the chain. The space between the axon terminal and the dendrite of the next cell is the **synaptic gap**.
61
what are the three different types of **neurotransmitters?**
**Noradrenaline** (also called norepinephrine) produces attention and triggers the "fight or flight response". People with ADHD (attention deficit hyperactivity disorder) seem to benefit from being prescribed noradrenaline
**Dopamine** is linked to feelings of pleasure and seems to play a part in addiction. Drugs that block dopamine receptors seem to help reduce symptoms in schizophtrenia.
**Serotonin** is the neurotransmitter for happiness to drugs which boost serotonin (by inhibiting serotonin re-uptake) can reduce depression
62
noradrenaline
**Noradrenaline** (also called norepinephrine) produces attention and triggers the "fight or flight response". People with ADHD (attention deficit hyperactivity disorder) seem to benefit from being prescribed noradrenaline-
- alertness
- concentration
- energy
63
dopamine
**Dopamine** is linked to feelings of pleasure and seems to play a part in addiction. Drugs that block dopamine receptors seem to help reduce symptoms in schizophtrenia.
- pleasure
- reward
- motivation/drive
64
serotonin
**Serotonin** is the neurotransmitter for happiness to drugs which boost serotonin (by inhibiting serotonin re-uptake) can reduce depression
- obsessions + compulsions
- memory
65
what are **hormones?**
hormones carry blood all around your body and take effect much more slowly, usually over minutes or hours. they are produced by a set of glands in the body called the **endocrine system**. Hormones are carried through the body in the blood. When they reach their target cells, they bind to the cell and change its function. Cells respond in particular way to particular hormones. Some hormones reach the brain and bring about mood changes by altering the production or re-uptake of neurostransmitters - for example, testosterone is linked to feelings of aggression.
66
difference between **neurotransmitters** and **hormones**
Neurotransmitters travel tiny distances and take effect in a fraction of a second. Hormones are different. They are carried by your blood all around your body and take effect much more slowly, usually over minutes or hours.
67
list the 5 main hormones and their functions
**thyroxine, produced in the thyroid gland-** promotes general metabolism in the body. lack of thyroxine results in hyperthyroidism which can also cause goitre.
**insulin, produced in the pancreas-** promotes metabolism of glucose. less secretion of insulin can cause diabetes.
**adrenaline, produced in the adrenal gland-** prepares the body for a fight or flight response by increasing the blood flow to limbs and facial muscles.
**testosterone, produced in the testes (male)** promotes development of secondary sexual characters and production of sperms.
**oestrogen, produced in the ovaries (female)** promotes development of secondary sexual characters and production of eggs.
68
define ‘aggression’
(also mention physical + social aggression)
Aggression is a form of **self-assertion** (putting yourself forward or standing up for yourself). However, it is done through causing harm to yourself, to other people or to your environment. This can be physical harm involving breakages and bruises or mental harm, involving fear and anxiety.
**Physical aggression** is violence.
**Social aggression** includes rumour spreading, insults and breaking off friendships. Threatening someone is aggressive because it causes them fear and anxiety, even if no violence occurs.
69
**nativist (nature)** view on aggression
Nativists (nature) argue that aggression is **innate** - it comes from within us. We are born with aggressive urges which never entirely go away, although self-discipline and a good upbringing might help us to control or re-direct these urges.
In this topic there are **two** nativist views:
(1) the biological view that aggression is an **evolutionary adaptation** and the (2) psychodynamic theory of aggression by **Sigmund Freud**
70
**nurturist (nurture)** view on aggression
Nurturists (nurture) argue that aggression comes from our **environment** and no one is born aggressive. Aggressive behaviour is learned or else produced by social pressures. Put anyone in the right situation and they will behave aggressively, but anybody's aggressive behaviour can be reduced or removed if they are put in better surroundings.
In the *Social Approach*, **Milgram** shows how an authority figure will produce aggression (delivering electric shocks); **Sherif** shows how out-group discrimination turns into aggression in the Robbers Cave study
In the *Learning Approach*, **Bandura** shows how aggression is transmitted through aggressive role models; it may also be conditioned through reinforcement **(Skinner)** or association **(Pavlov)**
71
hindbrain
a set of brain structures at the top of the spinal cord, mainly dealing with survival functions like breathing, heartbeat and consciousness.
72
midbrain
a set of brain structures above the hindbrain, mainly responsible for movement and for homeostasis (keeping the internal environment stable).
73
forebrain
a set of brain structures in the upper and outermost parts of the brain. It includes areas important for ‘higher’ mental functions like thinking, language and memory.
74
evidence for **brain structure: localisation**
**Phineas Gage** was a railway worker who received a substantial brain injury when an explosion caused a metal bar to be shot through his head. He survived, but suffered damage to the right frontal lobes of his brain. Gage’s personality changed following the injury. He became more impulsive and there was some memory impairment. This led later researchers to conclude that specific brain areas were responsible for specific psychological functions, an idea we now know as ‘localisation of function’.
**Broca (1861)** studied a patient (‘Tan’) who was unable to speak. ‘Tan’ died, and during post-mortem examination, Broca discovered that Tan had an area of brain damage in his left frontal lobe. He concluded that the ability to speak is linked to that specific region, adding weight to the idea that function is localised in the brain. This region is still referred to as ‘Broca’s area’ and patients who understand language but cannot speak are said to have ‘Broca’s aphasia’.
75
describe the structure of the brain
The brain can be subdivided into a large number of structures, each with a different function. The brain can be divided into the hindbrain (mainly survival functions), the midbrain (movement and homeostasis), the limbic system (emotions) and the forebrain (our ‘higher’ mental functions). The cerebral cortex is the outermost layer of the brain. It has many different areas, each taking care of a different function (e.g. language, sensation, movement, vision, thinking and problem solving).
76
define **‘drug’**
a substance put into the body deliberately in order to change its functioning
77
define **’psychoactive drug’**
a substance that changes the functioning of the brain. bringing about changes in thinking, feeling and behaviour.
78
define **’recreational drug’**
a psychoactive drug taken for non-medical reasons because the user wants or needs to feel the effects.
79
define **’agonist’**
(in relation to drug use)
any drug that increases activity at a specific type of synapse
(e.g. cocaine is a dopamine agonists)
80
define **’antagonist’**
any drug that decreases activity at a specific type of synpase.
81
define **’tolerance’**
(in relation to drug use)
a process in which the brain becomes more used to a drug, so more is needed to produce the same effect.
82
define **’dependance’**
(in relation to drug use)
a state where a user is unable to function fully unless they take a specific drug.
83
give an overview of recreational drugs and synaptic transmission
psychoactive drugs are drugs that change a person’s thinking, feeling or behaviour because they change the functioning of the brain. recreational drugs are psychoactives that people may take for non-medical reasons, usually because they bring about a pleasurable state. most recreational drugs work by changing what happens at synapses, for example, by increasing the level of neurotransmitter present in the synaptic gap by ‘pretending to be’ the real neurotransmitter or by blocking the action of the neurotransmitters.
- three recreational psychoactives are **cocaine, heroin and cannabis**
although each works in a different way, they all cause an increase in dopamine activity. the rise in dopamine activity affects a set of brain structures called the **reward pathway** in the **limbic system**. this provides an incentive to continue taking the drug because it feels rewarding to do so.
84
name 3 **recreational psychoactives**
heroin
cannabis
cocaine
85
what is **heroin?**
heroin is an illegal, highly addictive drug processed from **morphine**, a naturally occurring substance extracted from the seed pod of certain varieties of poppy plants. it is typically sold as a **white/brownish powder** that is ‘cut’ with sugars, starch or powdered milk.
can be taken via:
- injection
- snorting
- smoking
86
what effects does **heroin** have on the body?
(how does it work: synaptic transmission)
heroin binds to and activates specific receptors in the brain called mu-opioid receptors (MORs). the **neurotransmitters** bind to these receptors throughout the brain and body to regulate pain, hormone release and feelings of well-being. when MORs are activated in the reward centre of the brain, they stimulate the release of the neurotransmitter **dopamine**, causing a reinforcement of drug taking behaviour as it elicits a pleasurable response/feeling.
87
what are the **short-term** effects of **heroin** use?
once heroin enters the brain, it is converted into morphine and binds rapidly to opioid receptors. people who use heroin typically report a surge of **pleasurable sensation**. a ‘rush’. the rush is typically accompanied by a:
- warm flushing of thee skin
- dry mouth
- heavily feeing in the extremities
*nausea, vomiting and itching may also occur
after the **initial** effects, users usually will be drowsy for several hours, mental function is clouded, heart function slows and breathing is also severely slowed (sometimes enough to be life-threatening).
88
how can **opioids** act in the brain and nervous system?
- opioids can depress breathing by changing neurochemical activity in the brain stem, where automatic body functions such as breathing and heart rate are controlled.
- opioids can reinforce drug taking behaviour by altering activity in the limbic system. which controls emotions.
- opioids can block pain messages transmitted through the spinal cord from the body.
89
what are the **long-term** effects of **heroin** use?
repeated heroin use changes the physical structure and physiology of the brain, creating long-term imbalances in neuronal and hormonal systems that are not easily reversed.
- studies have shown some deterioration of the brain’s white matter, which may affect **decision-making abilities**, the ability to **regulate behaviour** and responses to stressful situations.
- heroin also produces profound degrees of tolerance and physical dependance. with physical dependance, the body adapts to the presence of the drug and **withdrawal** symptoms occur if use is reduced abruptly.
90
treatments for opioid use disorder/addiction
(pharmacological treatments: methadone)
**pharmacological treatments (medications)**
when people are addicted to opioids like heroin and they first quit, they undergo several **withdrawal** symptoms (pain, diarrhoea, nausea and vomiting), which may be severe. mediations can be helpful at this stage to ease craving and other physical symptoms that may prompt a person to relapse.
medications developed to treat opioid use disorders, work through the same opioid receptors as the addictive drug, but are safer and less likely to produce the harmful behaviours that characterise a substrate use disorder. three types of medications include:
**(1) agonists:** which activate opioid receptors
**(2) partial agonists:** which also activate opioid receptors but produce a smaller response
**(3) antagonists:** which block the receptor and interfere with the rewarding effects of opioids.
Methadone (Dolophine® or Methadose®) is a slow-acting opioid agonist. Methadone is taken orally so that it reaches the brain slowly, dampening the "high" that occurs with other routes of administration while preventing withdrawal symptoms. Methadone has been used since the 1960s to treat heroin use disorder and is still an excellent treatment option, particularly for patients who do not respond well to other medications. Methadone is only available through approved outpatient treatment programs, where it is dispensed to patients on a daily basis.
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what is **marijuana/cannabis? **
marijuana is a **greenish-gray** mixture of the dried flowers of Cannabis saliva. it is a ** cannabinoid**. It can be taken via:
- smoking
- water pipes
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what are the **effects** of **cannabis** ?
When marijuana is smoked, THC and other chemicals in the plant pass from the lungs into the bloodstream, which rapidly carries them throughout the body to the brain. The person begins to experience effects almost immediately (see "How does marijuana produce its effects?"). Many people experience a pleasant euphoria and sense of relaxation. Other common effects, which may vary dramatically among different people, include heightened sensory perception (e.g., brighter colors), laughter, altered perception of time, and increased appetite.
If marijuana is consumed in foods or beverages, these effects are somewhat delayed—usually appearing after 30 minutes to 1 hour—because the drug must first pass through the digestive system. Eating or drinking marijuana delivers significantly less THC into the bloodstream than smoking an equivalent amount of the plant. Because of the delayed effects, people may inadvertently consume more THC than they intend to.
Pleasant experiences with marijuana are by no means universal. Instead of relaxation and euphoria, some people experience anxiety, fear, distrust, or panic. These effects are more common when a person takes too much, the marijuana has an unexpectedly high potency, or the person is inexperienced. People who have taken large doses of marijuana may experience an acute psychosis, which includes hallucinations, delusions, and a loss of the sense of personal identity. These unpleasant but temporary reactions are distinct from longer-lasting psychotic disorders, such as schizophrenia, that may be associated with the use of marijuana in vulnerable individuals. (See "Is there a link between marijuana use and psychiatric disorders?")
Although detectable amounts of THC may remain in the body for days or even weeks after use, the noticeable effects of smoked marijuana generally last from 1 to 3 hours, and those of marijuana consumed in food or drink may last for many hours.
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how does **cannabis** work in the body?
THC’s chemical structure is similar to the brain chemical anandamide. Similarity in structure allows the body to recognize THC and to alter normal brain communication.
Endogenous cannabinoids such as anandamide (see figure) function as neurotransmitters because they send chemical messages between nerve cells (neurons) throughout the nervous system. They affect brain areas that influence pleasure, memory, thinking, concentration, movement, coordination, and sensory and time perception. Because of this similarity, THC is able to attach to molecules called cannabinoid receptors on neurons in these brain areas and activate them, disrupting various mental and physical functions and causing the effects described earlier. The neural communication network that uses these cannabinoid neurotransmitters, known as the endocannabinoid system, plays a critical role in the nervous system’s normal functioning, so interfering with it can have profound effects.
For example, THC is able to alter the functioning of the hippocampus (see "Marijuana, Memory, and the Hippocampus") and orbitofrontal cortex, brain areas that enable a person to form new memories and shift his or her attentional focus. As a result, using marijuana causes impaired thinking and interferes with a person’s ability to learn and perform complicated tasks. THC also disrupts functioning of the cerebellum and basal ganglia, brain areas that regulate balance, posture, coordination, and reaction time. This is the reason people who have used marijuana may not be able to drive safely (see "Does marijuana use affect driving?") and may have problems playing sports or engaging in other physical activities.
People who have taken large doses of the drug may experience an acute psychosis, which includes hallucinations, delusions, and a loss of the sense of personal identity.
THC, acting through cannabinoid receptors, also activates the brain’s reward system, which includes regions that govern the response to healthy pleasurable behaviors such as sex and eating. Like most other drugs that people misuse, THC stimulates neurons in the reward system to release the signaling chemical dopamine at levels higher than typically observed in response to natural rewarding stimuli. The surge of dopamine “teaches” the brain to repeat the rewarding behavior, helping account for marijuana’s addictive properties.
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what are the **long-term** effects of cannabis on the brain?
*has a lot of cognitive effects
Memory impairment from marijuana use occurs because THC alters how the hippocampus, a brain area responsible for memory formation, processes information. Most of the evidence supporting this assertion comes from animal studies. For example, rats exposed to THC in utero, soon after birth, or during adolescence, show notable problems with specific learning/memory tasks later in life. Moreover, cognitive impairment in adult rats is associated with structural and functional changes in the hippocampus from THC exposure during adolescence.
As people age, they lose neurons in the hippocampus, which decreases their ability to learn new information. Chronic THC exposure may hasten age-related loss of hippocampal neurons. In one study, rats exposed to THC every day for 8 months (approximately 30% of their lifespan) showed a level of nerve cell loss at 11 to 12 months of age that equaled that of unexposed animals twice their age.
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overview of aggression and brain structure and functioning
biopsychologists believe that aggression originates in the nervous system. because of localisation of function, it is possible that there are specific brain areas that are responsible for aggressive behaviour.
**limbic system-** a set of brain structures that include the amygdala. it is important in the generation and regulation of emotional responses.
**amygdala-** a brain structure that is important for experience fear in response to threats and also in recognising fear in other people. there are two amygdalae, one in each cerebral hemisphere.
**hypothalamus-** a brain structure involved in many homeostatic functions like eating. in predatory animals, the hypothalamus is involved in generating predatory aggression and hunting responses.
**pre-frontal cortex-** the front most, outer most area of the brain. one of its functions is to decide whether or not to act on impulses generated elsewhere in the brain.
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the **cerebral cortex** and its link to aggression
as **Phineas Gage** suggests, the brain’s **frontal lobe** plays an important part in decision-making and self-restraint. in particular, a region called the **pre-frontal cortex** seems to be particularly important. if it is damaged or malfunctions, aggression is a possible side-effect.
another brain structure that plays a role in aggression is the **corpus callosum** that links the left and right hemisphere. the two hemispheres need to communicate over long-term planning and thinking through consequences. damage to the corpus callous might also lead to more reckless behaviour.
*It's important to note that damage to the frontal lobe or corpus callosum doesn't create aggression itself. It just makes you less self-controlled and more inclined to act on the spur of the moment, especially in unfamiliar or confusing situations. This MAY turn out to mean aggressive behaviour, but it doesn't have to.
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the **limbic system** and its link to aggression
The **limbic system** is a sub-cortical area - part of the "old brain" that we share with other animals. It is also the brain's emotion centre where our most basic urges and desires (appetite, sleep, sex drive, fear) are regulated. For example, the thalamus is the brain's "switchboard" which receives signals and sends messages out to all the other areas. The **hypothalamus** has an important role in producing hormones.
However, the most important part of the limbic system for understanding aggression is the **amygdala**. The amygdala takes information from the thalamus and interprets it as a threat or not; it produces fear or aggression, the famous "fight or flight" response. Of course, if the amygdala malfunctions, then things which are threatening will not produce a fear response - or else harmless events will be interpreted as a threat, producing aggression. The case of Charles Whitman might be an illustration of this.
The relationship between the **amygdala** and the **frontal lobe** is very important. If the pre-frontal cortex is healthy, then willpower can resist the amygdala's urges of fear or aggression. In Adrian Raine's murderers, the amygdala behaved erratically and the pre-frontal cortex was under-active - a dangerous combination.
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aggression and its link to **hormones**
**low cortisol + high testosterone** = aggression
**Testosterone** is the hormone linked to aggression. Testosterone is produced in spurts, so the testosterone levels can rise suddenly and have an effect within minutes. It also varies seasonally in some animals, which is why red deer become aggressive in the mating period in the Spring. Males produce more testosterone than females (although female ovaries do produce testosterone) - and this is an explanation for why males are are aggressive than females on average.
A study of prisoners **(James Dabbs et al., 1987, 1995)** found testosterone levels were higher in those who had been convicted of a violent crime. Those with high testosterone levels were rated higher by other prisoners for being "tough".
Another hormone linked to aggression is **cortisol**. Cortisol is a hormone produced in the adrenal glands. While it is responsible for "waking us up" in the morning, its main job is managing stress levels. Cortisol seems to inhibit aggression, the same way that testosterone increases it (Van Goozen et al., 2007). Virkkunen (1985) report low levels of cortisol in violent offenders and Tennes & Kreye (1985) report low levels of cortisol in aggressive school children.
People with lower levels of cortisol are more aggressive because it means their **autonomic nervous system (ANS)** is under-aroused; aggressive behaviour is an attempt to create stressful situations which provoke cortisol release, stimulating the ANS.
There's also evidence linking aggression to HIGH levels of cortisol (eg. Gerra et al., 1997). Clearly, cortisol is complicated and does a lot of different things in the brain.
Animal studies also support the link between hormones and aggression. Rachel Adelson (2004) used rats as test subjects and used electricity to stimulate the hypothalamus; this led to the release of a stress hormone called corticosterone, which is part of the aggressive response.
If the rats had their adrenal glands removed and couldn't produce their own hormones, their aggression faded. However, when they were then injected with corticosterone, the hypothalamus activated. This shows a "feedback loop" in aggression: the hypothalamus triggers the release of the hormone but the hormone also activates the hypothalamus. This might explain the phenomenon of rage, when aggression spirals out of control.
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aggression and neurotransmitters
**low serotonin + high dopamine** = aggression
**Serotonin** is a neurotransmitter linked to mood and sadness. Treatment for depression often involves medicines that boost serotonin levels in the brain. However, low serotonin levels are also associated with increased aggression. This is because serotonin seems to inhibit aggression.
There is also a link between **dopamine** and aggression. Dopamine is a neurotransmitter linked to attention and pleasure. Increased dopamine levels are associated with increased aggression and anti-psychotic drugs (which reduce dopamine levels in people suffering from schizophrenia) seem to reduce aggressive moods and behaviours.
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evaluating (AO3) biological explanation of aggression
**Credibility**
**Raine et al. (1997)** used a PET scanner to compare brain functioning in murderers with a control group of non-offenders. They found that the murderers had differences of brain activity, particularly in the prefrontal cortex and the limbic system. This suggests that violent crime may be linked to unusual brain functioning.
**Swantze et al. (2012)** did a correlation study comparing the volume of PPs’ amygdalae with their self-reported levels of aggression. They found a significant correlation. This supports the view that individual differences in aggression are reflected in individual differences in the structure of the brain.
**Gorka et al. (2013)** compared how PPs’ brains reacted to pictures of angry and fearful faces between people who had and had not been drinking alcohol. Alcohol reduced the reactivity of the amagdalae and the right orbitofrontal cortex. This suggests that alcohol changes a person’s perception of threat and fear. This, in turn, might explain why people who have been drinking alcohol are liable to become aggressive and violent.
Since the 1990s, this research has been supported by new brain imaging techniques like PET and MRI. These scans show a correlation between unusual brain activity and aggressive or antisocial behaviour, such as Adrian Raine's observation that there was 11% less activity in the pre-frontal cortex of patients suffering from Antisocial Personality Disorder compared to a Control Group.
This evidence supports the nativist viewpoint that aggression is innate, present from birth and an unavoidable (and even a positive) part of human behaviour.
**Objections**
Although brain imaging techniques are reliable, there may be validity problems with these too. This is because the same structures in the brain (and the same neurotransmitters) seem to do different jobs. For example, the amygdala regulates both aggression and fear. Dopamine is associated with both pleasure and aggression and both high and low levels of dopamine are linked to aggressive behaviour.:
**Differences**
There are many studies supporting the idea that aggression is a learned behaviour. Bandura's "Bobo Doll" studies show that children imitate the aggressive behaviours they see in role models. Classical and Operant Conditioning both offer explanations for aggressive behaviour.
- **Classical Conditioning** shows that aggression is an unconditioned response to some stimuli (like threat) but may become a conditioned response to a neutral stimuli (like social embarrassment, unfamiliar people or drunkeness). This ties in with the Biological Approach because it assumes that unconditioned aggression is an instinctive response, but conditioned aggression is learned.
- **Operant Conditioning** shows that aggression is learned through reinforcement, either positive reinforcement (aggressive behaviour may bring you admiration and respect) or negative reinforcement (aggressive behaviour may make unpleasant things stop, by scaring people away).
Strict **Behaviourists** like B.F. Skinner would argue that ALL behaviour is learned and that human beings are born as *tabula rasa* (a bank slate), with aggression being added later.
**Biological determinists** would argue that ALL behaviour is hereditary and that human beings are born with a genetic destiny they cannot help but obey.
Most psychologists take a middle way between these extremes. Genetics gives us **predispositions** to behave a certain way, but we can resist these impulses if we try. We learn **specific behaviours**, but our genes give us broad instructions that affect what we learn and how easily we learn it.
- For example, Watson & Rayner conditioned Baby Albert to fear a white rat, but their experiment depended on the fact that Albert found something naturally frightening (a loud noise).
**Applications**
If the nativist viewpoint is correct, then aggressive behaviour is natural and unavoidable. It might be possible to identify people with extreme aggression at an early age, either by genetic screening, testing for testosterone or serotonin levels or by trying to identify those with an under-active pre-frontal cortex or malfunctioning amygdala. These individuals could be carefully monitored and perhaps kept away from jobs or roles where they might present a danger to the public (working with children or in hospitals, for example). There might be some jobs that would suit them well (the Armed Forces, perhaps, or contact sports like boxing or rugby).
Most psychologists adopt an **interactionist** approach, accepting that aggression is produced by nature and nurture. This is the view taken by Mara Brendgen; even though her twin study suggests that physical and social aggression both have a biological connection, she concludes that education at an early age may help children control their behaviour better.
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brain and aggression
(flowchart)
1. info from environment via senses
2. OFC exercises inhibitory control (stop/go)
3. amygdala interprets info as a threat (fear) or provocation (anger)
4. hypothalamus (activates aggressive behaviour)
5. hippocampus stores memory from previous experiences
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define **hormone**
chemical messenger that may alter the structure or functioning of an organ or organ system. Hormonal messages tend to be longer lasting than neural messages, and they often affect a much larger area.
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**endocrine gland**
a biological structure that releases one or more hormones. Collectively, the system of glands and hormones is called the endocrine system.
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**testosterone**
an androgen hormone, found in males and females but usually at a higher level in males. It affects the development of the sex organs, bone structure and skeletal muscles. It also may affect behaviour in various ways.
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define **organising effect**
(in relation to hormones)
the effect a hormone has in influencing the structure of an organ. Exposure to testosterone during development alters the structure of parts of the hypothalamus, amygdala and hippocampus.
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define **activating effect**
(in relation to hormones)
the effect a hormone has in influencing the functioning of an organ. In the brain, testosterone can act like a neurotransmitter, binding to receptors in the amygdala and enhancing its activity.
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evidence for aggression and hormones
**Neave & Wolfson (2003)** measured testosterone levels in male footballers before (1) a ‘home’ match; (2) an ‘away’ match; and (3) a training session. They found that testosterone levels rose significantly more before a ‘home’ match. They link this with the territorial aggression found in many species, and suggest it may partly explain the ‘home advantage’ that sports teams enjoy.
**Dabbs et al. (1995)** measures prisoners’ salivary testosterone levels and correlated this with their record of offending and their disciplinary record in prison. Those with the highest testosterone levels also were more likely to have committed violent offences and tended to have more prison rule violations on their record.
**Tricker et al. (1996)** did an experimental study in which men were randomly assigned to receive either a drug to increase their testosterone levels or a placebo. Measures of aggression were taken from the men themselves and also the people around them. No effect of testosterone was found, suggesting that the relationship between testosterone and aggression is not a straightforward causal one.
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**evolutionary psychology**
the view that genes are a significant influence on thinking, emotions and behaviour and have been shaped by evolutionary processes.
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mendelian trait
a characteristic that is influenced by a single gene (e.g. eye colour)
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polygenetic trait
a characteristic that is influenced by many genes acting all together (e.g. skin colour). most psychological traits (e.g. iQ, personality and aggression level) are polygenetic.
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family history study
a method for estimating the size of a genetic influence by seeing whether a trait runs in the family.
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adoption study
a method for estimating the size of a genetic influence by seeing whether adopted individuals are more similar to their biological or adoptive parents/siblings.
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twin study
a method of estimating the size of a genetic influence by seeing whether identical twins are more similar than non-identical twins on a particular trait.
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evidence for **adoption + twin studies**
**van den Oord et al. (1994)** found that adopted Dutch children aged 10-15 years were more similar in aggression to their biological than their adoptive siblings, suggesting that genes contribute to individual differences in aggression.
**Brendgen et al. (2005)** found that identical twins were more similar in aggression than non-identical twins. This shows that genes contribute to individual differences in aggression but Brendgen et al. also found that environmental influences outside the home also influence aggression levels.
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hostile aggression
aggression where the aim is to hurt the target
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instrumental aggression
aggression that is used to achieve another aim or goal.
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species
a group of organisms that are sufficiently similar genetically to produce offspring through interbreeding
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evolution
the gradual change in the characteristics of a species over time
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adaption
the process by which a species evolves to match the demands of its environment.
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gene
a sequence of DNA that codes for a particular characteristic in an organism
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allele
a genes that can exist in two or more version’s which give rise to variations in a particular characteristic (e.g. coding for brown or blue eyes).
