Brain Flashcards
Describe dendrites within the structure of neuron
The cell body of the neuron contains the cell nucleus.
Attached to the cell body are dendrites (branches at the top) that receive messages from other neurone to trigger an action potential within the cell.
Describe the axon within the structure of the neuron
The axon is attached to the cell body, it is a long branch of nerve fibres that connect the cell body to the end of the neuron which passes the action potential towards the axon terminals.
Describe axon terminals within the structure of a neuron
At the end of the axon terminals are terminal buttons (where the nerve impulse becomes a chemical message).
Terminal buttons are bulb shape structures that contain tiny sacs called vesicles that store neurotransmitters ready for the next stage of neural transmission.
What is the role of the neuron?
The neurons role is to pass messages between neurons using neurotransmitters to enable behaviour, thinking and emotions to be transmitted and to enable the working of the brain.
Describe the role of neurotransmitters
Neutrals mutters are chemicals that pass messages from one neurone to the next. This allows the brain to process thoughts and memories.
What is dopamine?
It is a neurotransmitter associated with pleasure feelings. It is associated with addition, as individual’s carry out actions to achieve the pleasure feeling. It is linked to drug addiction.
What is serotonin?
It is a neurotransmitter associated with mood control. Low levels are associated with depression and anxiety. It is also involved with functions such as sleep and regulating body temperature.
What is reuptake?
The process when any neurotransmitters not absorbed by a receptor are absorbed again by the presynaptic neuron.
What is the function of synaptic transmission?
A neurotransmitter crosses the synaptic gap/synapse.
When the action potential reaches the axon terminal of the presynaptic neuron, the terminal button releases the neurotransmitter from the vesicles into the synaptic gap.
On the dendrites of the postsynaptic neuron are receptors which receive the neurotransmitters.
Receptors are shaped so only one type of neurotransmitter can fit into them.
When the receptor detects the neurotransmitter it is absorbed and the message is passed on.
What is the role of the central nervous system?
The central nervous system is made up of the brain and the spinal cord.
It guides our behaviour, co-ordinating the body’s activities.
The spinal cord connect the brain to the rest of the body and allows messages to be passed from the body to the brain and from the brain to other parts of the body.
Describe recreational drugs
Recreational drugs are those that are used in the absence of medical grounds, but are taken by users for pleasure.
They are referred to as psychoactive drugs because they have an effect on the central nervous system which changes our mood perception or conscious experience.
Examples include nicotine, alcohol, cocaine, cannabis
What is the general effect if recreational drugs on transmission in the CNS
Most drugs have a specific mode of action at the synapse.
Drugs hijack the rewards system and produce pleasurable feelings without any adaptive function.
Most psychotic drugs of addiction work on the dopamine system.
What is the dopamine system?
A pathway in the brain which operates neurotransmitter dopamine the release of which leads to feelings of pleasure.
Describe nicotines effect in the transmission process in the CNS and how it can lead to addiction
Nicotine mimics the actions of a natural neurotransmitter, acetylcholine.
Nicotine bonds to a certain type of acetylcholine receptor called nicotinic receptors.
This causes an impulse in the neuron releasing more neurotransmitters, in this case dopamine.
Over time the brain reacts to this increase in dopamine by decreasing the number of dopamine receptors on the post-synaptic neuron to counteract the effect.
When nicotine is no longer present, because of the reduced number of dopamine receptors on the post-synaptic neuron the level of dopamine drops lower than would be for normal brain functioning.
This means more dopamine is required to stimulate the postsynaptic neuron to a normal level leading to desensitisation.
This leads to addiction because nicotine is now needed just to maintain the normal levels of dopamine in the brain.
What is desensitisation?
When more of a substance is required to achieve the same stimulation due to changes at the synapse.
State two strengths of arguments about drugs effects on transmission
👍Supporting evidence shows how recreational drugs create excess dopamine to give a ‘high’. This includes studies that found a pleasure centre in the brain of rats and studies that found an effect of cannabis in the hippocampus of mice.
👍There is credibility suggesting that recreational drugs firstly create more dopamine in the reward system, so give pleasure, and secondly have a desensitising effect leading to a tolerance addiction. This is because we observe people who take recreational drugs who at first experience great pleasure but then become addicted an need more to experience the same effects.
State two weaknesses of arguments about drugs effects on transmission
👎It is hard to study the mode of action of recreational drugs at the synaptic level as brain scanning techniques need to be more sophisticated. For example the focus is currently is in transmitter that are more easily studied so they are the ones conclusions will be made about.
👎The majority of scientific studies on recreational drugs are carried out using animal era therefore suffer from low generalisability. There are differences in the functioning of animal brains in comparison to human brains, this means it is not always possible to conclude findings represent the more complex human brain.
How many lobes is the brain made up of? (Name them)
The temporal lobe
The parietal lobe
The occipital lobe
The frontal lobe
What can damage to the frontal lobe lead to?
Damage to the frontal lobe has been linked to aggression. For example Phineas Gage suffered damage to the prefrontal cortex following an accident which seemed to affect his temperament.
What is lateralisation?
When the brain is in two halves called hemispheres.
What does bilateral mean?
When brain structures are the same across two hemispheres, such as the lobes.
Describe the prefrontal cortex
It is a brain structure involved in aggression.
A lot of dopamine, serotonin and norepinephrine connections are found in the prefrontal cortex. These neurotransmitters link to emotions, which is evidence that this area of the brain has a role in emotions.
The prefrontal cortex is in both hemispheres of the brain. On the left side it appears to have a role in regulating negative emotions from the amygdala in the limbus system.
What can damage to the prefrontal cortex lead to?
Damage to the prefrontal cortex might leave someone unable to plan long-term and lead them to immediate rewards. It could also mean that they are unable to control aggressive reactions.
What is the difference between an active and a less active prefrontal cortex?
An active prefrontal cortex regulates aggressive behaviour.
In a less active prefrontal cortex aggressive urges continue.
What is the role of the limbus system?
The limbus system has a role of self preservation for example, structures in the limbus system control our temperature and our flight or fight response.
What system is the limbus system linked to?
It is linked to our autonomic systems which respond automatically to danger rather than in a planned way.
What is the role of the hypothalamus in the limbic system?
The hypothalamus has a balancing role. It regulates our hunger and thirst as well as our response to pain, anger and sexual satisfaction.
What is the role of the amygdala in the limbic system?
The amygdala is the centre for identifying threat and it’s role is self-preservation.
It is thought to have a role in arousal, aggression and the fight response.
Describe cocaines effect on the transmission process in the CNS
Cocaine blocks the binding site on the reuptake receptor and stops the reuptake of dopamine back into presynaptic neuron.
This means there is excess dopamine in the synapse that leads to over-stimulation at the postsynaptic receptors.
More dopamine than usual in the reward pathway leads to feelings of euphoria.
Over time the brain reacts to this over-stimulation of the dopamine receptors by reducing the number of receptors in the post-synaptic neuron to counteract the effect.
This means more dopamine will be required to stimulate the postsynaptic neuron to normal level leading to desensitisation.
This leads to addiction because cocaine is now needed just to maintain the normal levels if dopamine in the brain.
What happens if the amygdala is stimulated using an electric current?
Aggression is shown.
What happens when the amygdala is removed?
The subject becomes more passive and unresponsive to fear.
What does a reduction in the size of the amygdala lead to?
An individual is three times more likely to commit a violent crime.
State two strengths of using brain functioning as an explanation for aggression
👍There is supporting evidence linking brain structure to aggression from Raine et al’s (1997) study. They found murderers who pleaded not guilty on the grounds of insanity had less activity in the prefrontal cortex than a control group of non-murderers.
👍Brain structure studies have increased reliability with neuroimaging techniques such as PET and fMRI scans. Greater precision and standardisation of these techniques have allowed structures of the brain to be more accurately and consistently measured.
State two weaknesses of using brain functioning as an explanation for aggression
👎The findings if the animal studies cannot be generalised to humans because of fundamental differences between humans and animals and are therefore not representative. Animals do not have the same prefrontal cortex as humans for example is it smaller in animals.
👎There are ethical concerns with the use of animals in studies that may have caused physical and psychological harm. Some would argue that studies such as Downer’s that involved brain lesions in monkeys are immoral and harmful to the animals.
State the aim of Raine et al’s classic study
The study aimed to how that brains of murderers who pleaded not guilty by reason of insanity were different from brains of non-murderers.
State 4 procedure points of Raine et als classic study
- The experimental group included 41 criminals pleading NGRI who had been charged with either murder or manslaughter. The control group was also made up of 41 pps.
- Each murderer was matched to a pp from the control group in terms of sex and age as well as similarities in other ways eg there were 6 control group pps with schizophrenia.
- All pps were given a continuous performance task which consisted of a sequence of blurred numbers to focus on.
- After a further 32 mins on the CPT a PET scan was completed to measure the metabolic rate in different areas of the brain in order to look at activity levels in those areas.
State 2 results of Raine et al’s classic study
They found that murderers who pleaded NGRI had less activity in the prefrontal areas of the brain.
There was no difference in the activity of the temporal areas of the brain between the criminals and the control group.
State the conclusions of Raine et al’s classic study
These brain differences have been associated with behavioural changes that could be related to violent behaviour. For example, dysfunction in the prefrontal cortex has been linked to impulsivity, lack of self-control and inability to learn the consequences of behaviour.
State two strengths of Raine et al’s classic study
👎The sample was high in validity as it was the latest sample of secretly violent offenders to e studied in this way and compared to matched control reducing participant variables. The murderers had already been referred to the imaging centre to gain evidence for their NGRI pleas and so this was a naturally occurring behaviour rather than something that ha been introduced by the research process.
👍The study was highly objective as it used PET scanning which can be interpreted by a number of different researchers in the same way without introducing researcher bias to the results. This in turn increases the reliability of results as the scans are easy to replicate and the procedures for carrying out scans can e easily controlled.
State two weaknesses of Raine et al’s classic study
👎The study has low generalisability as the experimental group was so specific eg murderers pleading NGRI. The findings are not representative of all offenders, even though it was violence that was being studied.
👎There are ethical concerns as the murderers were pleading NGRI. We may need to question their capacity to provide consent for their participation in the study if indeed they were truly experiencing mental health issues.
What do genes do?
Genes guide a lot of our characteristics and how we are. 50% inherited from our mother and 50% inherited from our father, which make up our genotype.
Describe how characteristics are inherited through evolution
Evolution is how inherited characteristics in organisms change from generation to generation. Changes in inherited characteristics lead to differentiation between species, it can evolve in positive or negative ways.
