AQA A Level Psychology Biopsychology
Terms in this set (23)
What is the nervous system
The nervous system is a specialised group of cells in our body and is our primary communication system, it collects processes and responds to different information and co-ordinates the working of different functions within the body. It is made up of both the central nervous system and the peripheral nervous system.
What is the central nervous system (CNS)
The CNS includes the brain and the spinal cord, the brain is the centre of all conscious awareness and it is the outer layer, the cerebral cortex, which distinguishes us from animals. The spinal cord is an extension o the brain and is responsible for our reflexes and movements.
The spinal cords main function is to relay information from the brain to the rest of the body.
The brain is made up of four main areas, the brain stem, the diencephalon, the cerebellum and the cerebral cortex.
The brain stem regulates automatic functions such as breathing and swallowing.
The diencephalon comprises the thalamus which takes nerve impulses from the senses to the brain and the hypothalamus that regulates body temp and hunger.
The cerebellum that controls motor skills and balance co-ordinating muscles to work together.
The cerebral cortex is divided into four lobes each with a different function:
The Parietal lobe for sensory information
The Occipital lobe for the processing of visual information
The Frontal lobe for thought and speech
The Temporal lobe for auditory information and memory
What is the peripheral nervous system (PNS)
The PNS is divided into two main sections the first being the somatic nervous system.
This is made up of 12 pairs of cranial nerves and 31 pairs of spinal nerves, containing both sensory and motor neurons it is also involved in reflex actions.
The autonomic nervous system is much more complex, it essentially regulates involuntary actions such as heart rate without any conscious awareness. It is made up of the sympathetic nervous system and the parasympathetic nervous system which have opposing effects on the body.
The sympathetic nervous system helps us deal with emergencies (fight or flight), it increases the heart rate, blood pressure and dilates pupils. It can also shut down non essentials like digestion.
The parasympathetic nervous system has the opposite effect of the fight or flight, as this response triggers homeostasis. This relaxes the individual after the emergency, slowing heart rate and non essentials back on.
What are neurons and outline the three main ones
Neurons are specialised cells designed for the transmission of information throughout the body, there are three types:
Sensory neurons, these carry impulses from receptors to the spinal cord/brain.
Relay neurons allow sensory and motor neurons to communicate with each other, located in the brain and spinal cord.
Motor neurons from synapses with muscles and when an impulse travels down the motor neuron it causes the muscle to contract.
Outline synaptic transmission
Action potential is the electrical signal that travels down the neuron to the axon ready to be passed on.
To cross a synaptic junction the end of an axon has many sacks of neurotransmitters known as vesicles which assist the message transfer. When the action potential reaches the synaptic vessels it causes them to release neurotransmitters, this is known as exocytosis.
The neurotransmitter diffuses across the synaptic junction and binds to receptor sites on the post synaptic knob. Once these sites are activated it produces either an excitatory or an inhibitory effect on the post synaptic knob.
This whole process takes a fraction of a second and is ended when the neurotransmitters are reabsorbed by the reuptake site.
As stated before based on the neurotransmitter released it can cause either an excitatory or an inhibitory effect. Excitatory neurotransmitters such as noradrenaline make it more likely for an excitatory signal to be sent to the post synaptic knob. This results in an excitatory post synaptic potential meaning the knob is more likely to fire.
The inhibitory neurotransmitters such as serotonin obviously have the opposite effect causing an inhibitatory post synaptic potential
Outline the endocrine system
The endocrine system works along side the nervous system and essentially is very similar in the sense that it controls vital functions in the body. However the endocrine system works much more slowly with much more powerful effects.
Instead of using nerves to transmit information it uses blood vessels to deliver hormones.
Endocrine glands produce and release hormones with the main ones being the pituitary gland and the adrenal glands.
The adrenal glands are on top of the kidneys. The outer part is called the adrenal cortex and the inner is the adrenal medulla. The adrenal cortex releases hormones which are essential to life whereas the adrenal medulla are not.
The adrenal cortex produces cortisol which regulates cardiovascular and anti-inflammatory functions.
The adrenal medulla releases adrenaline, which increases heart rate and thus blood flow to the brain, and noradrenaline which constricts blood vessels causing blood pressure to go up.
Outline the fight or flight response
When a person experiences a life threatening or stressful situation the body responds with what is known as the fight or flight response. It is an evolutionary adaptive survival mechanism enabling us to react quickly to certain stimuli.
However this response now days is activated too often to non life threatening situations such as exam stress.
It works by as follows, when faced with a stressful situation the amygdala is activated a signal is then sent to the hypothalamus which uses the sympathetic nervous system to communicate with the rest of the body.
It's response to acute stress takes the sympathomedullary pathway (SAM). When the SNS is triggered it sends a signal to the adrenal medulla which releases adrenaline into the blood. The adrenaline causes the heart to beat faster allowing for more blood into the brain. After a while the parasympathetic nervous system is triggered causing the stress response to be dampened down.
After 20 minutes if the stress is continued, it is then known as chronic stress and the response is different. Instead of the sympathomedullary pathway it takes the hypothalamic pituitary adrenal system (HPA).
The hypothalamus releases the chemical corticotrophin releasing hormone into the blood stream, this arrives at the pituitary gland causing it to release adrenocorticotrophic hormone. This is then targeted at the adrenal gland, specifically the adrenal cortex, causing the release of cortisol which gives a quick burst of energy and higher pain thresholds. However it can lower both the immune system and impair cognitive performance.
Evaluate the fight or flight response
:( - Research suggests that females have a different behavioural response to stress, known as tend and befriend. This is due to women's role as a PCG, they are thus more likely to protect themselves and their children through nurturing behaviours and forming alliances with other women. This suggests that therefore women may have evolved differently saying that the fight or flight response can not be applied to both genders.
:( - The flight part of fight or flight could be detrimental to the safety of women's offspring. Research conducted with rats found that women may release oxytocin which inhibits flight. This hormone has been shown to increase relaxation. This research further shows evidence for the fight or flight not being able to be applied to women.
:( - The fight or flight response is an evolutionary survival technique however modern day life can trigger this too frequently in inappropriate situations. This can be detrimental to out health and cause coronary heart disease. Furthermore too much cortisol can result in us being more prone to illness. Therefore the very process that is designed to save our lives could in fact cause illness.
:( - Research suggests that there are other responses before fight or flight. He said that humans are more interested in avoiding confrontation rather than fleeing it. This is known as the freeze response where by people are hyper vigilant and alert to any danger. The freezing focuses attention and helps people find new information in order to deal with the threat. This limits the value of insight psychologists have in accurately explaining response to stress.
Outline the localisation of the brain
The motor cortex is responsible for all voluntary movements and is located within the frontal lobe in the precentral gyrus. Both hemispheres have a motor cortex with each side controlling opposing sides of the body. Different parts of the motor cortex control different parts of the body.
The somatosensory cortex detects sensory information from all over the body, it is located within the parietal lobe in the postcentral gyrus.
The visual centre is located within the visual cortes inside the occipital lobe. nerve impulses from the retina travel along the optic nerve to the thalamus, passing on this information to the visual cortex.
Auditory cortex is concerned with hearing, it lies within the temporal lobes in each hemisphere of the brain. The pathway begins in the cochlea within the ear where sound waves are converted to impulses that travel down the auditory nerve to the auditory cortex.
There are two language centres, the first is responsible for speech production and is known as the Broca's area, it is said that this is in the posterior portion of the frontal lobe in the left hemisphere. The other is responsible for speech understanding and is called Wernicke's area, it lays within the posterior portion of the left temporal lobe.
Evaluate the localisation of the brain
:) - There is evidence that supports the localisation of function of language. Patients with damage to the areas where language centres are experience aphasia, this is an inability to understand and produce speech. Specific damage to Broca's area demonstrates the importance of this region for speech production and the same with Wernicke's area.
:( - Not all researchers agree that the brain has localisation of function. One researcher founded the equipotential theory. It states that basic motor and sensory functions are localised but higher mental functions are not and that if there is a brain injury intact areas of the rain will take over for specific functions.
:( - Some research shows us that how the brain communicate with each other is more important than the specific brain regions being responsible for functions. Wernicke stated that different brain areas must interact with each other to effectively function. This is supported by a case study done into a man who lose the ability to read which resulted from damage to the connection between the visual cortex and Wernicke's area. This suggests that complex tasks require different structures of the brain to deal with the same stimulus as opposed to localisation of function.
:( - Other research suggests that there are large individual differences in how peoples brains are activated in language activities. Research done by Harasty found that there were even gender differences in the size of the brain associated with language, and it was further found that women have proportionally larger Broca's and Wernicke's areas than men resulting in women using their language more. This therefore limits the value of the insight that psychologists have regarding the localisation functioning in the brain.
Outline lateralisation and the split brain research behind it
Lateralisation of the brain simply means that the brain is split into two halves via a corpus collosum (a bundle of nerve fibres). It is thought that each hemisphere has functional specialisms ie. language is mostly on the left side whereas motor skills are more on the right.
To test the abilities of each side of the brain two researchers conducted split brain research. They had participants who had had there corpus collosum cut for medical reasons. They would send information to one hemisphere at a time and see how they reacted to it.
The patients were flashed a word on a computer screen which was spaced apart so that they could flash it on one side of the screen and only one eye would see it and vice versa. When they flashed a word to the right side of the face and asked what they had seen they would successfully say the word. However when it was flashed on their right side they would say they had not seen anything however they could draw a picture of it.
This can be explained as when information goes through the right visual field it goes to the left hemisphere where there is a language centre and thus they can say what they have seen. However the information from the left visual field goes to the right where there is no language centre but there is the visuo-spatial centre meaning they can draw it
Evaluate the lateralisation of the brain
:( - The advantage of having hemispheric lateralisation is that it increases neural processing capacity. This is due to the fact that if we use just the left side for language then the right side would be free to do another task at the same time. However there is very little evidence to show that this happens.
:( - Lateralisation may be beneficial in some circumstances for example some people who are mathematically gifted will have superior right hemispheric skills however these people are also more likely to suffer from higher rates of allergies and general problems with their immune systems
:( - Lateralisation can change with age, research has shown that initial lateralised patterns in young people can change into bi-lateral patterns in healthy older adults. Specifically language became more lateralised to the left hemisphere in children but by the age of 25 lateralisation decreased with every year.
:( - The sample sizes in the original studies were often as small as three participants and also many had confounding variables before they became split brain and thus we must be cautious when generalising the findings to the whole population
Outline brain plasticity
Brain plasticity refers to the ability of the brain to change and adapt as a result of experience.
It is now believed that the brain continues to create neural pathways all the time and alter existing ones.
When people gain new experiences, nerve pathways that are used frequently create stronger and more connections and pathways that are rarely used become weaker and some may break down completely. Although this is seen as a huge benefit there is however a natural decline in cognitive performance with age, which may also be due to the the brains constant adaptation. To try and help elders reverse this a researcher found that teaching 60 year olds to juggle increased grey matter in the visual cortex. However, when they stopped practising the changes were again reversed.
A researcher found that playing video games requires complex cognitive and motor demands. A group of participants played Super Mario for 30 minutes a day for two months and found significant increase in grey matter in both the cortex and hippocampus.
Research has shown that meditation can change the inner workings of the brain. They found that when comparing monks to regular humans with no meditation experience that the monks had much greater activity of gamma waves than the students.
Outline functional recovery of the brain
It seems that stroke victims are able to regain functioning of the brain several months after a stroke. It seems that the brain can rewire itself so that other parts can take over from damaged areas, neurons around these areas form new circuits to working areas.
Wall found dormant synapses within the brain which are essentially spare unused synapses. When the brain is damaged areas around these dormant synapses seem to become very active and thus unmasking them. These new connections create a lateral spread of activation which over time develops new structures.
Stem cells are unspecialised cells that have the ability to be used in any part of the body and become specialised. There are three main ways to use them:
1) Implanted into the brain and replace dead cells
2) Transplanted stem cells secrete growth hormone that rescue dead cells
3) Transplanted stem cells form a neural pathway linking uninjured areas to injured areas
Evaluate plasticity of the brain
:) - Animal studies provide evidence for the brains ability to demonstrate plasticity based on the environment. A researcher found that rats who were put in a rich environment compared to those which were in a simple cage with no stimulating structures had an increased number of neurons specifically in the hippocampus. (difficult to extrapolate)
:) - However there has also been research done onto humans as well that also provides evidence for brain plasticity. Maguire used an MRI scan to see how much grey matter there was in the brain of London taxi drivers. He found that the posterior hippocampus volume was significantly larger compared to a control group. Demonstrating a positive correlation between rich stimuli and plasticity.
Evaluate functional recovery of the brain
:) - Animal studies provide evidence for functional recovery of the brain after trauma. A psychologist transplanted stem cells directly into damaged areas of the rats brain, he found after just three months there was neuron development compared to the control group who had no change. There was also a stream of stem cells moving towards other injured brain sites, this all therefore suggests the brains ability to recover after trauma.
:( - Functional recovery of the brain may be an ability that we lose as we get older. Neural routine is much greater within children than adults and this lead to psychologists suggesting that the best way to recover from a brain injury after childhood is to develop behavioural coping strategies to help deal with the traumatic injury.
Outline the four main ways of directly studying the brain
Functional Magnetic Resonance Imaging (FMRI)
This technique measures changes in the brain whilst a person is doing a task. Using a strong magnetic flux it tracks ion movement within the brain, which is within the blood. If a part of the brain becomes more active then more oxygen is required, oxygen travels within the blood and thus it links ion levels to brain activity.
An EEG measures electrical activity in the brain. Electrodes are places all over the scalp to detect any small electrical impulses. There are four different EEG patterns that are usually detected:
Alpha waves when awake, Beta when physiologically aroused (also seen in REM) and Delta+Theta waves seen in sleep.
Event-related Potentials (ERP)
Similar to EEG's however this looks at the brain reacting to a stimulus instead of just stand alone. It looks at very quick high voltage changes within the brain, it is difficult to isolate the other electrical activity and thus to remove background noise the target stimulus is presented many times to the patient and the response is averaged out and background noise removed. There are two types of waves occurring after presentation of stimulus: Sensory ERP's before 100ms and Cognitive ERP's after 100ms of stimuli.
Post Mortem Examinations
These are used after a patient has died to physically see the neurobiology of a particular behaviour. For example Broca's work analysing the brains of people who had speech problems led him to discover the important area responsible for speech.
Evaluate each way of studying the brain
:) - Non invasive and does not expose brain to potentially harmful radiation as is the case with other scan methods
:) - Offers a more objective and reliable measure of psychological processes than is possible with verbal reports. It is a useful way of investigating psychological behaviour using a quantitative report
:( - A FMRI measures changes in ion level rather than directly measuring brain activity it is not then a direct measure of neural activity. This means it is not a truly quantitative measure of mental activity in these brain areas
:( - People argue that FMRI overlooks the networked nature of the brain and rather just looks at the localised activity. It is communication within the brain that is key, not just each area working separately
:) - An advantage of the EEG technique is that it provides a constant recording of the brains activity rather than just a still image. This means the researcher can more accurately measure brain activity in a particular task
:) - EEG's are good for clinical diagnosis for example epilepsy can be diagnosed easily as when someone is experiencing a seizure the EEG reading should suddenly change
:( - EEG's can only see what is going on in superficial areas of the brain and not the deeper regions and thus it cant see important areas such as the hippocampus
:( - Although there are many seperate electrodes as part of an EEG a lot of the time a group of electrodes will detect the spike in voltage change and thus it is hard to say exactly where the change originates from
:) - As ERP's provide a continuous measure of brain activity in response to a stimuli it makes it possible to determine exactly how a stimulus affects the brain and thus drawing a cause and effect relationship
:) - An ERP can measure the reaction to stimuli without the need for the patient to learn any techniques, and thus be fairly covert.
:( - As ERP's are so small and difficult to pick out from other electrical activity within the brain it means many trials must be done and thus this places limitations on what it can truly answer or prove
:( - Similar to EEG's, ERP's only detect significantly strong voltages and thus many of the recordings gained are only from superficial regions of the brain
:) - This allows for a more detailed anatomical examination of the brain of areas that through other methods would not be possible as they are too deep within the brain, for example the hippocampus
:) - Harrison claims that post mortem studies have played an extremely important role in our understanding of schizophrenia. He suggests that as a result of pot mortem's we have discovered abnormalities within the brain that change levels of dopamine which is associated with disorders
:( - There are many confounding variables that may have affected the brain when conducting a post mortem, such as the time between death and doing it, the point at which they are at in their illness etc. This means that when extrapolating the findings it must be done with caution
:( - This technique is retrospective as the patient is already dead and thus it makes it impossible for the psychologist to follow up on anything between the physical side and the cognitive side of the patient
Outline the three biorhythms
Biorhythms are biological processes that show cyclical variation over time and reflect the influence of earths rotation on animals
These follow day and night and are 24 hours, the ones psychologists are most interested in is the sleep wake cycle
These last less than 24 hours and the main example is the stages of sleep that humans undergo which is around 90 mins long
These are longer than 24 hours with the main example being woman's menstrual cycle which lasts 28 days
Outline and evaluate circadian rhythms
Circadian rhythms last approximately 24 hours with the sleep wake cycle, body temperature and hormone cycle being the best known. They are often referred to as a body clock to help animals meet the varying demands of day and night.
Circadian rhythms are driven a suprachiasmatic nuclei, located in the hypothalamus, which is known as master circadian pacemaker. This pacemaker is constantly reset by light through a process called photoentrainment, light sensitive cells within the eye detect brightness and then send this information to the SCN, which in turn controls the activity of the circadian rhythm.
The sleep wake cycle is affected by this external cue however it is also said that there is an endogenous clock that is free running and works within 24-25 hours.
Another circadian rhythm is the body temperature rhythm, its thought to be at a lowest temperature of 36 degrees at 430am and 38 degrees at 6pm.
:) - Michel Siffre conducted an experiment which provides evidence for circadian rhythms existing despite isolation from light. He spent long periods of time living in caves with no external cues and found that his natural circadian rhythm settled at just over 24 hours. Further research where participants were placed in a WWII bunker also found that their circadian rhythms stayed at between 24-25 hours
:( - However critics were quick to point out a huge flaw in his research. Although they were not exposed to natural light they were exposed to light from torches which has the same effect as natural effect. A researcher wanted to prove that fake light could act as an external zeitgeber thus they shone a torch on the back of peoples leg and found it could alter circadian rhythms between 22-28 hours. This suggests that the free running part of circadian rhythms were not properly measured
:( - An important criticism is that most of the findings into circadian rhythms are not absolute and found many different individual differences within participants varying from 13-65 hours. This suggests that there must be other factors other than a free running endogenous clock that may have effected their sleep wake cycles.
:) - Finally to overall evaluate, there are significant real world applications that research into circadian rhythms has found. Circadian rhythms has shown to directly affect digestion, heart rate and hormones, and therefore we can clearly see it can be used with Chronotheraputics which is the study of timing affects on medication. For example certain drugs that are released and consumed at times of the day where hormones are at peaks
Outline and evaluate infradian and ultradian rhythms
Ultradian rhythms span for less than a day, an example would be the five stages of sleep which lasts for around 90 mins before it repeats itself.
The first two stages are light sleep with the brain producing beta and alpha waves and eventually theta when you start to fall deeper into sleep. The third and fourth stages consist of mainly delta waves resulting in the person being very difficult to wake up but still conscious, in this sleep is where its thought growth hormone is released to repair the body. The final stage, stage 5 is REM sleep with EEG activity resembling that of an awake brain.
:) - Research suggests that in REM sleep people dream. Researchers woke up participants during the night when their brain activity was characteristic of REM sleep. They found that participants were highly likely to be dreaming at this time, with some having matching eye movements in sync with the dream
:( - However these findings were not absolute as there was found to be widespread individual differences because some dreams were recorded outside REM sleep and some dreaming just didn't occur in REM sleep. This suggests that other factors may have affected their dreaming so it suggests more research is needed on topic before firm conclusions are drawn.
Infradian rhythms span over times longer than a day but less than a year, on example would be the menstrual cycle whereby ones a month females pituitary gland will release hormones which cause a follicle to ripen an egg. When the egg is ready progesterone is released to help the womb before pregnancy. After two weeks if there is no fertilisation progesterone levels decrease and the womb is shed.
Another infradian rhythm is seasonal affective disorder, which is a depressive condition during the winter months that is due to fewer hours of sunlight. It is thought that more darkness increases melatonin which makes the individual display depressive symptoms.
:( - Although the menstrual cycle is said to be an endogenous system that is naturally controlled by hormones research has shown otherwise. One researcher found that women who live together ten to synchronize their menstruation each month. Sweat from one group of women rubbed on the upper lips of another group resulted in both groups menstruating at the same time. This is due to the pheromones present in the sweat, this suggests that exogenous cues altered the women's infradian rhythm.
:( - SAD could in fact not just be an infradian rhythm but rather a disrupted circadian rhythm due to external zeitgeber's such as decreasing sunlight hours. During winter people have to get up at the same time due to school/work etc. however they may choose to sleep earlier as it will have been dark for longer. This may lead to confusing the body into thinking time is shifting and thus causing negative symptoms similar to that of jet lag.
Finally to overall evaluate there are many different real world applications that research into biorhythms has allowed for. Because of research done into SAD, phototherapy has been established, this is where strong lights are used which are person looks at during the evening to change levels of melatonin and serotonin. This therefore means that research to support biological rhythms is an important area of applied psychology which can benefit society.
Outline endogenous pacemakers and exogenous zeitgebers
One of the most important endogenous pacemakers is the suprachiasmatic nucleus which is a tiny cluster of nerve cells located in the hypothalamus, connected to the eye. This acts as the master clock linking other brain regions that control sleep and arousal. Neurons within the SCN sync with each other so that target neurons elsewhere int he body receive timed signals.
In the morning light penetrates the eyelid to the retina which stimulates the SCN to cause the pineal gland to regulate the amount of melatonin being produced. Thus the more light the less of this chemical and the more awake someone will feel.
Light is the most dominant exogenous zeitgeber in humans, with the ability to entrain and reset internal clocks. It also has the power to entrain other oscillators, as a ket ingredient of the protein clock, crypto-chrome is light sensitive. The eye contains special light detecting cells called melanopsin which are responsible for carrying signals to the SCN to help set the bodies daily cycle.
As well as light, other social cues also play a role in our circadian rhythms, meal times for example act as an exogenous zeitgeber as the cells in the liver are likely to be reset by eating.
Aschoff found that jet lag could be reduced if we spent more time outside at their destination traveled to, and not this being due to the light but rather the social cues around you allowing your body to adjust quicker
Evaluate endogenous pacemakers and exogenous zeitgebers
:) - Burgess found that bright light exposure before an east west flight can help minimize jet lag. Participants rhythms were shifted back by 2 hours per day for three days. Other research suggests the spectral composition of light is very important and that exposure to warm light over 5 weeks was much more effective then blue light. This confirms light as an external zeitgeber
:( - Evidence for the SCN was found when conducting an experiment on hamsters. Psychologists removed the SCN and found that their usual circadian rhythm disappeared and when it was put back it was re-established. However critics are quick to point that a weakness of this research is that it was done on animals that are quantitatively different to humans and thus must be very cautious when extrapolating the findings this therefore means the research can be criticized for anthropomorphism
:( - It is more appropriate to suggest that circadian rhythms are multi dimensional in the sense that it can be influenced by both endogenous and exogenous factors. To think of it as a blended system allows us to look at the role of both nature and nurture, thus this approach is less reductionist
:) - Overall to evaluate there are many real world applications within this area of psychology. This research can be used to help reduce the potential of major industrial accidents which could save both lives and money, such as Chernobyl.