Biopsychology: Paper 2 (16 markers) Flashcards
(98 cards)
1
Q
A01: Outline the full process for acute stress in the fight or flight response
A
- In acute stress, the amygdala processes fearful and threatening stimuli.
- The amygdala sends a stress response to the hypothalamus , which activates the sympathetic nervous system (SNS), which delivers more blood to areas of the brain that require oxygen.
- The SNS then triggers the adrenal medulla to secrete the hormones called adrenaline and noradrenaline.
- The realise of adrenaline triggers the body’s fight or flight response by increasing the heart rate and expanding the air passages of the lungs.
- Also, the noradrenaline constricts blood vessels which maintain blood pressure in times of stress.
- Lastly, after the threat has passed, the parasympathetic nervous system is activated, which calms the body down after the fight or flight response. For example, it slows down the heart rate and restores digestion.
2
Q
A01: Outline the full process of the fight of flight response to chronic stress
A
- A major component of the chronic stress response is the hypothalamic-pituitary-adrenal axis (HPA axis).
- When a chronic stressor (an example could be exam stress) is perceived, the hypothalamus secretes CRH: a hormone that is the main organiser of the body’s response to stress.
- Next, the hormone CRH causes the pituitary gland to release a hormone called ACTH, which plays a role in maintaining blood pressure.
- The release of ACTH then triggers the adrenal cortex to produce cortisol, which is known as the stress hormone, which regulates the stress response of the body by keeping inflammation down.
- Lastly, the hypothalamus then maintains the levels of cortisol keeping it stable by utilising a negative feedback loop.
- For example, if cortisol levels get too high then a signal is sent to the hypothalamus, which inhibits ACTH, inhibiting the release of cortisol.
- Therefore, this reduces the cortisol levels back down to normal.
3
Q
A03: Why does the fight of flight response not tell the whole story?
A
- Gray argues that the first response to danger is to avoid confrontation.
- This is demonstrated by the ‘freeze response’, in which humans are hyper alert as they assess the situation and determine the best action to take for the particular threat that is imposed on them.
- Therefore, the ‘fight or flight response’ does not show an accurate representation of the body when faced with a threat.
4
Q
A03: Why is the fight of flight response not required in modern life?
A
- While the fight or flight response may have been a useful survival mechanism for our ancestors, who faced genuinely life-threatening situations (e.g. from predators), modern day life rarely requires such an intense biological response.
- The problem for modern humans arises when the stress response is repeatedly activated. E.g. increased blood pressure that is characteristic of the SNS activation can lead to physical damage in the blood vessels and eventually to heart disease.
- This suggests that the fight or flight response is a maladaptive response in modern-day life.
5
Q
A03: Why does research into the fight of flight response suffer from beta bias?
A
- Early research into the fight or flight response was typically conducted on males (androcentrism) and this meant researchers assumed that the findings could be generalised to females. This means research into the fight or flight response suffers from beta bias as psychologists assumed that females responded in the same way as males.
6
Q
A03: What research shows that women actually have a different fight or flight response?
A
- The fight or flight response is typically a male response to danger and more recent research suggests that females adopt a ‘tend and befriend’ response in stressful/dangerous situations due to the release of oxytocin in response to stress (which is associated with maternal bonding and a mother’s natural protective urges)
- According to Taylor et al. (2000), women are more likely to protect their offspring (tend) and form alliances with other women (befriend), rather than fight an adversary or flee.
- Furthermore, the fight or flight response may be counterintuitive for women, as running (flight) may put their offspring at risk of danger.
- Therefore, women deal with stress through different system responses than fight or flight responses, in which they are more likely to ‘tend and befriend’ due to the excretion of oxytocin.
7
Q
A03: How does genetic data show that it is unlikely women have the same flight or fight response as men?
A
- In fact, this is supported by genetic data.
- Lee and Harley (2012) found the SRY gene, exclusively on the male Y chromosome, associated with aggression and priming for a fight-or-flight response to stress.
- They conclude that the absence of this gene in females, together with the action of oestrogen and oxytocin, mean that the response is not likely to occur in females - showing that the fight or flight response is not an adequate explanation for female responses.
8
Q
A03: How does contradictory research show that men actually go through the same ‘tend and befriend’ response as women?
A
- However, a strength of the fight or flight response is that there is evidence for positive rather than ‘fight or flight’ behaviours.
- Von Dawans et al (2012) challenge the view that, under stress, men respond only with fight or flight, whereas women are more prone to ‘tend and befriend’.
- It was found that acute stress can actually lead to greater cooperative and friendly behaviour, even in men. This could explain the human connection that happens during times of crisis such as the 9/11 terrorist attacks.
- One reason stress may lead to greater cooperative behaviour is because human beings are fundamentally social animals and is the protective nature of human social relationships that has allowed our species to thrive.
9
Q
A01: What is localisation of function?
A
Localisation of function refers to the principle that specific functions have specific locations within the brain. According to this theory, if a certain area became damaged, the function associated with that area will also become damaged.
10
Q
A01: How has research found that different locations of the brain are associated with different functions?
Provide an example and what they found.
A
- Scientists such as Broca and Wernicke discovered that certain parts of the brain are associated with particular physical and psychological functions using case studies.
- For example, Broca used postmortem to study the speech area of the brain. He had a case of a patient called Tan who had a speech difficulty who was found to have a lesion in the left hemisphere of his brain due to Syphilis.
- This led Broca to conclude that this area was responsible for speech production, calling it the Broca’s area and that the left side of the brain had been responsible for language and speech.
Before these discoveries, scientists supported the holistic theory of the brain – that all parts of the brain were always involved.
11
Q
A01: Where is the Somatosensory Area located and what is its function?
A
- The somatosensory area is located in the parietal lobe and receives incoming sensory information from the skin to produce sensations related to pressure, pain, temperature, etc.
- Different parts of the somatosensory area receive messages from different locations of the body.
12
Q
A03: What is evidence to support the existence of the somatosensory area performing its designated function?
A
Robertson (1995) found that this area of the brain is highly adaptable, with Braille readers having larger areas in the somatosensory area for their fingertips compared to normal sighted participants, showing that the somatosensory area has a specific function for sensory information within the brain.
13
Q
Case studies such as Broca’s are limited as they are based on a small and unique sample…
A03: Localisation of Function
A
One limitation is that case studies are based on a small and unique sample. This is a limitation because these results cannot be generalised to other people as case studies are unique to the individual and cannot be replicated for verification. Therefore, we cannot be sure if the brain works to the localisation theory in all individuals.
14
Q
Functional recovery limits the idea of the brain being localised…
A03: Localisation of Function
A
One limitation of localisation is the notion of functional recovery. This is a limitation because after brain trauma, the brain is able to rewire and reorganise itself in order to recover lost function, which can involve another part of brain taking over that function.
This is illustrated in the case study of Jodie Miller, who had hemispherectomy. While she had almost all of her right hemisphere removed, she was able to walk within 10 days.
Therefore, this suggests localisation is not fixed to specific areas for specific function; functional recovery supports holistic theory suggesting the brain is working as whole unit.
15
Q
Contradictory evidence on Broca’s findings…
A03: Localisation of Function
A
Although there is evidence from case studies to support the function of the Broca’s area, more recent research has provided contradictory evidence.
Dronkers et al. (2007) conducted an MRI scan on Tan’s brain, to try to confirm Broca’s findings. Although there was a lesion found in Broca’s area, they also found evidence to suggest other areas may have contributed to the failure in speech production.
This is a limitation because these results suggest that the Broca’s area may not be the only region responsible for speech production and the deficits found in patients with Broca’s aphasia could be the result of damage to other neighbouring regions.
16
Q
Biologically reductionist…
A03: Localisation of Function
A
One limitation is that critics argue that theories of localisation are biologically reductionist in nature and try to reduce very complex human behaviours and cognitive processes to one specific brain region.
This is a limitation because critics suggest that a more thorough and holistic understanding of the brain is required to truly understand complex cognitive processes like language.
17
Q
Different areas of the brain interact with each other rather than act independently..
A03: Localisation of Function
A
One limitation is that some psychologists suggest that it is more important to investigate how the brain areas communicate with each other, rather than focusing on specific brain regions. Wernicke claimed that although the different areas of the brain are independent, they must interact with each other in order to function.
An example to demonstrate this is a man who lost his ability to read, following damage to the connection between the visual cortex and the Wernicke’s area, which was reported by Dejerine.
This is a limitation because this suggests that interactions between different areas produce complex behaviours such as language.
Therefore, damage to the connection between any two points can result in impairments that resemble damage to the localised brain region associated with that specific function. This reduces the credibility of the localisation theory.
18
Q
A wide range of evidence to support the idea that different areas of the brain have different functions…
A03: Localisation of Function
A
Furthermore, advances in brain imaging techniques such as PET scans have led scientists to be able to discern and describe the neurological basis of mental processes. For example, in Tulving et al’s research involving tasks that required the use of episodic and semantic memory were able to show how these different types of long-term memory may be located on opposite sides of the pre-frontal cortex, whilst procedural memory may have been located in the cerebellum.
For example, Paterson used brain scans to demonstrate how Wernicke’s area was active during a listening task (where people had to understand what’s being said) and Broca’s area was active during a reading task.
These are strengths because there is a wide range of evidence to support the idea that different areas of the brain have different functions.
19
Q
Individual differences are not taken into account…
A03: Localisation of Function
A
One limitation is that some psychologists argue that the idea of localisation fails to take into account individual differences.
Research for this comes from Herasty who found that women have proportionally larger Broca’s and Wernicke’s areas than men, which can perhaps explain the greater ease of language use amongst women.
This is a limitation however because it suggests a level of beta bias in the theory: the differences between men and woman are ignored, and variations in the pattern of activation and the size of areas observed during various language activities are not considered.
20
Q
What is Hemispheric Lateralisation?
A01: Lateralisation and Split-Brain Research
A
Hemispheric lateralisation refers to the fact that one side of the brain controls the opposite side of the body, and each hemisphere of the brain is responsible for different functions.
Research has shown that the left hemisphere of the brain is responsible for language and speech whereas the right hemisphere of the brain is responsible for recognition and visual-motor tasks.
21
Q
What is an easy way to remember the functions of each hemisphere?
A
Left hemisphere of the brain– processes Language
Right hemisphere of the brain– processes Recognition; identification of something (such as faces and objects)
22
Q
What is the difference between what the left and right hemisphere control?
(in terms of body and visual fields)
A
The left hemisphere receives information from and controls the right-hand side of the body and receives information from the right visual field.
The right hemisphere receives information from and controls the left-hand side of the body and receives information from the left visual field.
23
Q
Why were split-brain patients used in Sperry and Gazzaniga’s Split Brain Research and why had they been different from normal people in terms of information processing in their hemispheres?
A01: Lateralisation and Split-Brain Research
A
In split-brain patients, the corpus colosseum (which normally allows for communication between the left and right hemispheres) was cut out due to seizures.
They took advantage of the fact that information from the left visual field went to the right hemisphere and information from right visual field went to the left hemisphere of the brain.
As their corpus collosum had been severed, communication between these two hemispheres had been prevented meaning that information can only be processed in the hemisphere that received it.
24
Q
What happened in Sperry and Gazzaniga’s Split Brain Research and what did they find?
A01: Lateralisation and Split-Brain Research
A
Sperry presented them with information on the right and left visual fields, ensuring a barrier was put between the patient’s eyes so that the hemisphers processed information individually.
When he presented information on the right visual field, which is sent to the left hemisphere of the brain, they weren’t able to recognise what they seen but could speak what they had seen.
When presented information on the left visual field, which is sent to the right hemisphere of the brain, they could recognise what they seen, but cannot speak what they had seen.
Therefore, research has shown that the left hemisphere of the brain has a specific localised function for language whereas the right hemisphere of the brain has a specific localised function for visual-motor tasks and recognition.
25
Age affects hemispheric lateralisation
A03: Lateralisation and Split-Brain Research
One limitation is that research has found that hemispheric lateralisation decreases with age. As we grow up our brain becomes more lateralised as the left hemisphere is used more for speech production.
However, as we pass the age of 25, we become more bilateral, and the functions of each hemisphere not limited to one half of the brain.
This is a disadvantage to the theory as it shows that lateralisation is not constant throughout our lives and specific functions of the separate hemispheres become less important over time.
26
Brain is plastic --> lateralisation (hemispheres performing different functions from each other) not fixed.
A03: Lateralisation and Split-Brain Research
However, one limitation of split-brain research is that research has found language may not be restricted to the left hemisphere.
Turk et al discovered a patient who suffered damage to the left hemisphere but developed the capacity to speak in the right hemisphere, eventually leading to the ability to speak about the information presented to either side of the brain.
This is a limitation as it suggests that perhaps lateralisation is not fixed and that the brain can adapt following damage to certain areas.
27
Low mundane realism
A03: Lateralisation and Split-Brain Research
- The experimental procedure used in split brain patients is unlike how these individuals would process information and act in normal day to day life (Tasks are artifiical and lack mundane realism) resulting in low external validity.
- In real life, both hemispheres would have access to information by moving the head.
28
Split-brain patients are a unique and rare small sample size.
A03: Lateralisation and Split-Brain Research
Unfortunately, much of the research into lateralisation is flawed because the split-brain procedure is rarely carried out now, meaning patients are difficult to come by.
Such studies often include very few participants, and often the research takes an idiographic approach.
Therefore, any conclusions drawn are representative only of those individuals who had a confounding physical disorder that made the procedure necessary. This is problematic as such results cannot be generalised to the wider population.
29
Very scientific ---> high internal validity & can be replicated.
A03: Lateralisation and Split-Brain Research
One strength is that Sperry’s procedure was closely controlled
This is a strength because Sperry’s research used scientific methods and empirical data that were not affected by any extraneous variables.
For example, Patients were given eye patches, and images were flashed up for a very brief time (fractions of a second), meaning there was no possibility of looking over and using the other visual field. This strengthens the internal validity of the studies.
30
Research support from brain scans in normal participants.
A03: Lateralisation and Split-Brain Research
One strength is research shows that even in normal brains, the two hemispheres process information differently. For example, Fink et al used PET scans to identify which brain areas were active during a visual processing task.
When 'normal' participants were asked to attend to global elements of an image (such as looking at a picture of a whole forest) regions of the right hemisphere were much more active.
When required to focus in on the finer detail (such as individual trees) the specific areas of the left hemisphere tended to dominate. This suggests that, at least as far as visual processing is concerned, hemispheric lateralisation is a feature of the normal brain as well as the split-brain.
31
Research support from animal studies regarding multi-tasking
A03: Lateralisation and Split-Brain Research
Gazzaniga and Sperry's research is supported by a study from Rogers which found that brain lateralisation improves our ability to multi-task.
He saw that chickens were able to both gather food and be aware of predators at the same time. Using only one hemisphere to engage in a task leaves the other hemisphere free to engage in other functions.
This shows that brain efficiency is improved by brain lateralisation and our hemispheres being able to work simultaneously.
32
Animal studies cannot be generalised to humans.
A03: Lateralisation and Split-Brain Research
However, because this research was carried out on animals, it is impossible to conclude the same of humans.
This is because chickens do not have a corpus collosum and have a different structure of their brains from human.
This is therefore a limitation because research from animals cannot be generalised to humans. In fact, despite animal studies, very little empirical evidence has been provided to show that lateralisation provides any advantage to the functioning of the brain in humans.
33
What is Brain Plasticity?
A01: Plasticity and Functional Recovery of the Brain
Brain plasticity refers to the brains ability to change and adapt in both its structure and function because of experiences and new learning.
These changes could be as a result of damage, or to meet the cognitive needs of learning new skills
34
What is synaptic pruning?
A01: Plasticity and Functional Recovery of the Brain
This means nerve pathways that are used frequently develop stronger connections whereas neurones that are rarely or never used eventually die in a process called synaptic pruning.
Thus brain plasticity makes the brain a more efficient communication system over time.
35
Why do children learn a language faster than adults?
A01: Plasticity and Functional Recovery of the Brain
This process of synaptic pruning is highly active in the brains of newborns and children
In fact, infants have the highest amount of neural synapses as an infant than any other period of an individual's lives meaning that their brain is more plastic.
Many of these synaptic connections are pruned meaning fewer but stronger connections are formed as we grow older.
This explains why children find it easier to learn languages than adults due to this higher plasticity.
36
How does the Brain recover function after trauma?
A01: Plasticity and Functional Recovery of the Brain
Stroke victims have been able to regain functioning.
Although some parts of the brain may be damaged or even destroyed because of trauma, other parts of the brain appear able to take over the functions that were lost as the brain re-wires itself over time.
These regenerative developments in the brain arise from the brain’s plasticity.
37
What is Neural Unmasking?
Fully outline this process.
A01: Plasticity and Functional Recovery of the Brain
Wall discovered 'dormant synapses' in the brain—connections that exist anatomically but remain inactive due to low neural input.
Surrounding brain damage can increase input, activating these dormant synapses.
This activation leads to connections in normally inactive brain regions, creating a lateral spread of activation which fosters new structure development in the brain over time.
38
Brain Plasticity can also have negative consequences...
A03: Plasticity and Functional Recovery of the Brain
However, brain plasticity can be negative. This is a limitation because the brain’s ability to rewire itself can sometimes have maladaptive consequences. For example, research from Medina shows that prolonged drug use has shown to result in poorer cognitive functioning as well as an increased risk of dementia later in life.
39
Support for the existence of negative brain plasticity comes from the existence of pornography...
A03: Plasticity and Functional Recovery of the Brain
Overuse of pornography can lead to creating negative functional and structural changes in the brain due to the damaging of dopamine receptors, leading to negative effects such as desensitisation to rewards.
For example, Max Planck Institute for Human Development found a negative correlation between pornography use and the volume of the striatum, an area of the brain that makes up part of the reward system.
40
Individual differences in functional recovery...
A03: Plasticity and Functional Recovery of the Brain
While there is evidence for functional recovery, it is possible that this ability can deteriorate with age. Elbert et al. concluded that the capacity for neural reorganisation is much greater in children than in adults, meaning that neural regeneration is less effective in older brains. This may explain why adults find change more demanding than young people.
Therefore, to improve lateralisation and split-brain research we must consider individual differences when assessing the likelihood of functional recovery in the brain after trauma.
41
Positive effects of brain plasticity: Research support from Taxi Drivers.
A03: Plasticity and Functional Recovery of the Brain
Moreover, Maguire’s research on London taxi drivers found that they had more volume of grey matter in the posterior hippocampus than those in a matched control group as taxi drivers must memorise a large variety of routes on the London map to become an efficient taxi driver.
42
Research support for educational attainment affecting functional recovery.
A03: Plasticity and Functional Recovery of the Brain
Evidence from Schneider shows that a person's educational attainment could influence the degree to which a person’s brain recovers its functionality. He found that the more time that brain injury patients had spent in education, the greater the chance that their brain had recovered to full functionality. For example, two fifths of patients who recovered to full functionality had more than 16 years of education compared to about 10% with patients who had less than 12 years of education.
43
Real life applications of brain plasticity and functional recovery.
A03: Plasticity and Functional Recovery of the Brain
A strength of brain plasticity is its practical application. Understanding the process of recovery has contributed to neurorehabilitation. The techniques include movement therapy and electrical stimulation of the brain to treat cognitive problems experienced by a stroke.
This shows that although the brain may be able to fix itself to a point, this process requires further intervention if it’s to be successful.
Thus, one strength is that it has helped create interventions that can support recovery in those with brain processes.
44
Research support for brain plasticity from animal studies: Neurones and Environment
A03: Plasticity and Functional Recovery of the Brain
Furthermore, there is research support for brain plasticity from animal studies. Kempermann investigated whether an enriched environment could alter the number of neurones in the brain.
He found evidence of an increased number of new neurones in the brains of rats housed in complex environments compared to rats housed in laboratory cages, specifically the hippocampus which is associated with the formation of new memories.
45
Research support from animal studies: Kitten & Functional Recovery
A03: Plasticity and Functional Recovery of the Brain
Hubel and Wiesel sewed 1 eye of a kitten shut and analysed the response.
The area of the visual cortex associated with the shuteye was still working and carried out processing information in the open eye.
This is a strength as it demonstrates how the loss of function leads to compensatory activity in the brain (evidence of neural plasticity.)
46
Research support for brain plasticity: Video Games
A03: Plasticity and Functional Recovery of the Brain
Research from Kuhn shows that playing video games activates many different complex motor and cognitive demands.
He compared a control group with a video game training group that was trained for two months in Super Mario. He found a significant increase in grey matter in brain areas such as the cortex, hippocampus and cerebellum, which was not evident in the control group who didn’t play Super Mario.
Therefore, they concluded that the video game training resulted in new synaptic connections in brain areas such as spatial navigation and motor performance, which were skills that were important in getting better at the game.
47
Danelli
- Case of 14 year old EB. At the age of 2 and a half, EB had hemispherectomy of the left side of his brain to remove a tumour (basically brain surgery).
- This removed the language areas of Broca's and Wernicke's Areas.
- After sturgey, EB lost all language abillity but was able to recover this language abillity after 2 years.
- FMRI scans actually showed that the right hemisphere followed a 'left-like blueprint' for language and could perform language tasks usually taken up by the right side of the brain.
48
Phineas Gage: Case Study for Localisation of the Brain
- He had experienced huge changes to personality as result of damage to frontal lobe after experiencing an iron rod that pierced his skull.
- Before the accident, he was calm and reserved and after the accident, he became rude, hostile and quick tempered.
- Demonstrates that there are localised areas of brain as the area that Gage damaged links to reasoning, control and mood.
48
Phineas Gage: Case Study for Brain Plasticity and Functional Recovery
- Shows the brain's resilence
- An iron rod pierced through his brain and a 'teacup' of his brain exited the top of his skull.
- He still miraculously survived and was able to walk after 24 days, recovered physically and had slight memory loss but still was able to live for 12 years after.
49
How do EEGs study the brain?
A01: Ways of Studying the Brain
EEGS record the electrical activity of neurons. Electrodes are placed on the scalp to record changes. Computers then analyse readings from the electrodes and produce a graph.
Brain wave patterns coming from the activities of target neurons can be seen on the screen and turned into a brain map or an overall account over time.
Different frequencies of brain waves are found. Brain waves can be rhythmic and even (healthy) or arrhythmic and uneven (unhealthy).
We can use EEGs to show abnormal activity in the brain such as arrhythmic brain waves to detect disorders such as epilepsy, making it an easy and safer way to diagnose disorders.
50
How do fMRIs study the brain?
A01: Ways of Studying the Brain
A technique, which uses a magnetic wave, for measuring changes in brain activity when performing a task.
Measures changes in blood flow in particular areas of the brain, which indicates increased neural activity in that area.
If a particular area of the brain becomes more active, there is an increase demand for oxygen and the brain responds to this by increasing blood flow.
Therefore, researchers can produce maps which show the areas of the brain involved in a particular mental activity.
51
How do ERPs study the brain?
A01: Ways of Studying the Brain
ERPS are very small voltage changes in the brain that are triggered by specific events or stimuli because of cognitive events.
Scientists use ERPS to isolate a specific event by presenting the event several times and the responses are then statistically averaged together.
Any extraneous neural activity that is not related to the specific stimulus will not occur consistently, whereas activity linked the stimulus will.
This has the effect of cancelling out the background neural ‘noise’, making the specific response to the stimulus in question stand out more clearly.
52
How do Post-Mortem examinations study the brain?
A01: Ways of Studying the Brain
Surgical dissection of the brain of person who has died from natural events like accidents.
Documents changes in behaviour and compares behaviour before damage
Looks at symptoms of the person when they were alive to see where the damage area is.
53
Can you give an example of when and how post-mortem was used to study the brain and improve our understanding of it?
A01: Ways of Studying the Brain
Broca used post-mortem to study the speech area of the brain. He had a case of a patient called Tan who had a speech difficulty who was found to have a lesion in the left hemisphere of his brain due to Syphilis. Discovered the language function on the left side of the brain.
54
What are two strengths of fMRIS?
- High spatial resolution.
- Does not rely on radiation.
A03: Ways of Studying the Brain
Produce images that have very high spatial resolution. This is a strength because it depicts detail by the millimetre, providing a very clear picture of how brain activity is localised.
Unlike other scanning techniques such as PET, it does not rely on the use of radiation. This is a strength because if administered correctly fMRIs are virtually risk-free, non-invasive and straightforward to use.
55
What are two limitations of fMRIs?
- Only measures changes in blood flow.
- Poor temporal resolution.
A03: Ways of Studying the Brain
fMRIs only measures changes in blood flow in the brain, it isn't a direct measure of neural activity in particular brain areas. This is a limitation because this means fMRIs are not a truly quantitative measure of mental activity in these brain areas.
Poor temporal resolution mean there is around a 5-second time-lag behind the image on screen and the initial firing of neuronal activity. This is a limitation because it detects changes in brain activity slowly meaning it is hard to accurately predict the onset of brain activity.
56
What are two strengths of EEGs?
- High temporal resolution
- Useful in clinical diagnosis, but how?
A03: Ways of Studying the Brain
EEG technology has extremely high temporal resolution. This is a strength because today's EEG technology can accurately detect brain activity at a resolution of a single millisecond, and this had been successfully applied to improve our understanding of the sleep stages accurately to a single millisecond.
Useful in clinical diagnosis such as recording abnormal neural activity associated with epilepsy. This is a strength because conditions such epileptic seizures are caused by disturbed brain activity meaning that when the normal EEG reading suddenly changes, we can detect this and thus provide an appropriate diagnosis as to whether someone experiencing seizures has epilepsy.
57
What is a limitation of EEGs?
- Low spatial resolution
A03: Ways of Studying the Brain
Low in spatial resolution. This means that EEGs records the activity of many thousands of neurons rather than a single neuron in one specific location of the brain. This is a limitation because the EEG signal is not useful for pinpointing the exact source of neural activity, and as a result does not allow researchers to distinguish between activities originating in different but adjacent locations.
58
What are two strengths of ERPs?
- More specificity than raw data from EEGs
- Measures processing of stimuli even when a behavioural response is absent.
A03: Ways of Studying the Brain
Use of ERP’s addresses issues of EEGs as they bring more specificity than raw data from EEGS, while maintaining its high temporal resolution. This is a strength because it has led to their widespread use in the measurement of cognitive functions and deficits (such as maintenance of working memory) in research.
Can measure the processing of stimuli even in the absence of a behavioural response. This is a strength because ERP recordings make it possible to monitor 'covertly' the processing of a particular stimulus without requiring the person to respond to them.
59
What are two limitations of ERPs?
- Background noise/extraneous material need to eliminated
- Only sufficiently strong voltage changes are recorded.
A03: Ways of Studying the Brain
Background noise and extraneous material must be eliminated to collect pure data and establish an ERP. This is a limitation because this is very difficult to do as for example other thoughts cannot be removed when a participant is asked to perform a particular task. Therefore, it may require many trails.
Only sufficiently strong voltage changes generated across the scalp are recordable. This is a limitation because important electrical activities occurring deep in the brain are not recorded, meaning that the generation of ERPs tends to be restricted to the neocortex.
60
What are two strengths of Post-Mortem Examinations?
- Detailed examinations
- Provides a foundation for early understanding of key processes in the brain.
A03: Ways of Studying the Brain
Provide a detailed examination of the anatomical structure and neurochemical aspects of the brain that is not possible with other scanning techniques. This is a strength because post-mortem examinations can access areas like the hypothalamus and hippocampus, which other scanning techniques cannot. This therefore provide researchers with an insight into these deeper brain regions, which often provide a useful basis for further research.
Vital in providing a foundation for early understanding of key processes in the brain. This is a strength because Broca used postmortem to study the speech area of the brain. He had a case of a patient called Tan who had a speech difficulty who was found to have a lesion in the left hemisphere of his brain due to Syphilis. Discovered the language function on the left side of the brain.
61
What are two limitations of Post-mortem Examinations?
- Ethical issues
- After death brain can decay in some places.
A03: Ways of Studying the Brain
Post-mortem studies raise ethical issues of consent from the patient before death. For example, HM lost his ability to form memories and was therefore not able to provide consent, nevertheless, post-mortem research has been carried out on his brain.
After death the brain can start to decay in some places. This is a limitation because observed damage to the brain may not be linked to the deficits under review but to some other unrelated trauma or decay (neuronal changes during and after death). Therefore, there is a potential that abnormalities in the brain may not be the cause of a particular behaviour and could be caused by a different illness, meaning that it is low in internal validity.
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A01: Circadian Rhythms
How do Circadian Rhythms tell us when to sleep?
Circadian rhythms dictate when we should be awake and sleeping.
Light and darkness are external signals that determine when we feel the need to sleep and when to wake up.
The circadian rhythm keeps us awake if there is daylight, prompting us to sleep as it becomes dark.
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How does Circadian Rhythms affect our sleep drive?
A01: Circadian Rhythms
The circadian rhythm also drops and rises at different times of the day, so our strongest sleep drive usually occurs in two dips between 2-3 am and between 1-3 pm.
The sleepiness we experience during these circadian dips is less intense if we have sufficient sleep and vice versa.
When we have been awake for a long period of time, homeostasis tells us that the need for sleep is increasing because of the amount of energy used up during wakefulness.
This homeostatic drive for sleep increases gradually throughout the day, reaching its maximum in the late evening when most people fall asleep.
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Research support for the existence of Circadian Rhythms...
A01: Circadian Rhythms
Siffre
Investigated the effect of the removal of light (exogenous zeitgeber) on the circadian rhythm of the sleep cycle and wake cycle.
He spent 6 months in a cave without light and sound and continued to fall asleep and wake up on a regular schedule.
His free-running biological rhythm settled to around 25 hours despite removing the exogenous zeitgeber, light, highlighting circadian rhythms persistence despite the removal of light (exogenous zeitgebers.)
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Generalisation issues
A03: Circadian Rhythms
One limitation is that use of case studies and small samples has generalisation issues.
This is because studies of the sleep/wake cycle tend to involve small groups of participants, e.g. Siffre (only himself as a participant).
This is a limitation because people may not be representative of the wider population which limits the generalisations made to the wider population.
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Individual Differences.
A03: Circadian Rhythms
There may be individual differences within these small sample sizes as sleep/wake cycles may actually vary widely from person to person.
For example, Siffre did the cave study again at the age of 60 and found that his internal clock ticked much more slowly when he was a young man, suggesting age can affect circadian rhythms.
In addition, a study by Jeanne Duffy et al., 2001, revealed that some people have a natural preference for going to bed early and rising early (known as 'larks') whereas others prefer the opposite ('owls').
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Extraneous variables not controlled --> low internal validity.
A03: Circadian Rhythms
One limitation is that there is poor control in studies-confounding variables.
This is because although participants in the all the studies were deprived of natural light, they still had access to artificial light. For example, Siffre turned a lamp on when he woke up, which remained on until he went to bed.
It was assumed this would have no effect on the free-running biological rhythm however, it was later shown that participants circadian rhythms could be changed using artificial light. Therefore, extraneous variables could have affected the circadian rhythms of the participants in these studies, making the research low in validity.
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Understanding of consequences of disruption to circadian rhythms ---> improve efficiency and positive implications on economy.
A03: Circadian Rhythms
One strength of research into circadian rhythms is that it provides an understanding of the adverse consequences that occur when they are disrupted (desynchronisation).
For example, night workers engaged in shift work experience a period of reduced concentration around 6 in the morning (a circadian trough) meaning mistakes and accidents are more likely (Boivin et al., 1996).
Research has also pointed to a relationship between shift work and poor health - shift workers are 3x more likely to develop heart disease than people who work more typical work patterns (Knutsson, 2003).
This shows that research into the sleep/wake cycle may have real-world economic implications in terms of how best to manage worker productivity and prevent harmful effects of a disruption to circadian rhythms ensuring that in the long term, workers can prosper and positively impact the economy by being able to work more (without having to take off time for sickness) and be more efficient.
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Real life applications into teenager's academic performance.
A03: Circadian Rhythms
One strength is that research into circadian rhythms has real life applications.
A number of researchers such as Wolfson and Carskadon recommend that the school day start a couple of hours later to fit in with the typical teenage chronotype (sleep pattern).
Hormonal shifts in the teenage body mean that getting to sleep becomes more difficult and therefore adolescent students tend to be rather sleepy at the start of the school day.
This is a strength because research into circadian rhythms has shown benefits for academic and behavioural performance when lessons start later in the day, including reduced dependence on caffeine
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Does not account for social cues
A03: Circadian Rhythms
However, this research is flawed as it does not account for the existence of social cues. This is a limitation because shifting the start of the day is disruptive for parents and teachers, and it limits the number of extracurricular activities after school.
Also, critics of the proposal suggest that a later school day would not actually reduce sleep deprivation, it would simply mean that teenagers would stay up later and still be exhausted!
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Evolutionary theory
A03: Circadian Rhythms
The evolutionary explanation for the day night cycle of humans and other animals specialised for the day activity is that we are not specialised for night time activity and thus we have a sleep period at night to protect us from accidental harm and predators.
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Real life applications to prevent disruption to circadian rhythms (blue light)
A03: Circadian Rhythms
As we known the psychological effects of exposure to light, particularly blue light, can disrupt our natural melatonin levels making our bodies think it is daytime when it is not, thus disrupting our circadian rhythms.
This understanding of the effects of light is a strength because research into the connection between blue light and sleep has allowed psychologists to provide people with advice on how to maintain a healthy sleep pattern such as by avoiding blue light at least two to three hours before sleep to ensure a healthy circadian rhythm is maintained.
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What are ultradian rhythms?
What happens during the cycle example given?
A01: Ultradian and Infradian Rhythms
Ultradian rhythms span a period of less than a day. One example of this rhythm are the five stages that make up a person’s sleep.
Each cycle repeats itself about 90-100 minutes throughout the night, with different durations.
- In the first stage, a person enters a light sleep, with brain waves still going at a high speed.
- At stage two, breathing pattern and heart stats to slow.
- As a person enters deep sleep in the third and fourth stages their brainwaves slow and their breathing and heart rate decreases as they start to generate delta waves.
- During the fifth stage called REM sleep, dreaming occurs the most and the EEG pattern resembles a waking person.
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What are infradian rhythms?
Provide an example.
A01: Ultradian and Infradian Rhythms
- Infradian Rhythms have a duration greater than 24 hours. An example in this in humans would include the female menstrual cycle in humans (monthly cycles)
- There are considerable variations in this length of this cycle, some women experience a relatively short 23 day cycle whereas some have a cycle as long as 36 days. Average appears to be 28 days
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What is the Basic Rest Activity Activity Cycle?
A01: Ultradian and Infradian Rhythms
- The ultradian rhythm is also sometimes known as BRAC, Basic Rest-Activity Cycle.
- We move progressively from a state of alertness into a state of physiological fatigue approximately every 90 minutes.
- Research suggests that the human mind can focus for a period of about 90 minutes, and towards the end of these 90 minutes the body begins to run out of resources, resulting in loss of concentration, fatigue and hunger.
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Research support suggests that the menstrual cycle ( an example of an infradian rhythm) is, to some extent, governed by exogenous zeitgebers (external factors).
--> Cave
A03: Ultradian and Infradian Rhythms
Reinberg (1967) examined a woman who spent three months in a cave with only a small lamp to provide light.
Reinberg noted that her menstrual cycle shortened from the usual 28 days to 25.7 days.
This result suggests that the lack of light (an exogenous zeitgeber) in the cave affected her menstrual cycle, and therefore this is a strength as it demonstrates the effect of external factors on infradian rhythms.
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Further evidence to suggest that exogenous zeitgebers can affect infradian rhythms.
---> Sweat rubbed on lips
(2 marks)
A03: Ultradian and Infradian Rhythms
Russell et al. (1980) found that female menstrual cycles became synchronised with other females through odour exposure. In one study, sweat samples from one group of women were rubbed onto the upper lip of another group.
Despite the fact that the two groups were separate, their menstrual cycles synchronised.
This suggests that the synchronisation of menstrual cycles can be affected by pheromones, which have an effect on people nearby rather than on the person producing them.
These findings indicate that external factors (such as exogenous zeitgebers) must be taken into consideration when investigating infradian rhythms and that perhaps a more holistic approach should be taken, as opposed to a reductionist approach that considers only endogenous influences.
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There are methodological limitations of synchronisation studies.
A03: Ultradian and Infradian Rhythms
There may be many factors that may affect the menstrual cycle, including stress, diet, exercise etc.
These are confounding variables and may explain why other studies have failed to replicate the findings of Russell et al (1980).
This is a problem because it suggests that the original study may be flawed due to lack of control and shows low reliability of the findings.
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Practical Applications - Sleep Calculators
A03: Ultradian and Infradian Rhythms
One strength is that research into sleep has had many practical applications.
This is useful because psychologists have tried to find ways to reduce the effect that social cues have on natural wake. Research has found that people tend to feel tired after they wake up not due to having a lack of sleep but rather because they have woken up mid sleep cycle, in which people are more likely to feel groggy and disoriented. This had led to the invention of sleep calculators, to help adults wake up at the end of their sleep cycle, recommending at least five sleep cycles (7.5 hours) with 15 minutes to fall asleep (average time it takes a human to fall asleep.
Therefore, it has been beneficial to society and bettering our understanding of sleep cycles.
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Research support for BRAC --> Violinists
A03: Ultradian and Infradian Rhythms
One strength is that there is research support for the Basic Rest Activity Cycle, in which the 90-minute cycle seen during sleep also occurs during the day.
For example, Ericsson et al. (2006) found that, among a group of elite violinists, practice sessions were usually limited to a duration of no more than 90 minutes at a time and the violinists frequently napped between practice sessions. The researchers also discovered the same pattern among other musicians, athletes, chess players and writers, supporting the existence of a 90-minute ultradian cycle of alertness and fatigue, during the waking day.
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Ultradian rhythms and their existence is supported by the evolutionary theory.
A03: Ultradian and Infradian Rhythms
One strength of ultradian rhythms is that evolution of multiple sleep cycles, including the progression through different sleep stages before entering deep sleep, can be seen as a survival advantage due to role of vigilance during the lighter sleep stages.
By having multiple sleep cycles before entering deep sleep, ancestral humans could maintain a certain level of awareness and responsiveness to their environment.
Therefore, this is a strength because this flexibility provided by multiple sleep cycles made them better equipped to detect potential threats or changes in their surroundings, instead of having one straight sleep cycle which could have made humans more vulnerable to threats.
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Circadian and ultradian rhythms seem to be connected and perhaps should not be seen as separate processes.
A03: Ultradian and Infradian Rhythms
Czeisler showed that the longest period of REM sleep coincides with the lowest point in the circadian body temperature cycle.
This could mean that both processes use the same internal body clock known as the endogenous pacemaker.
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Individual differences of ultradian rhythms.
A03: Ultradian and Infradian Rhythms
While overall patterns of sleep cycles are consistent there are however some individual differences with Newborn babies spending 80% of sleep in REM compared to 20-25% of adults.
This suggests that the stages of sleep are not a simple process but adapt to developmental needs of the individual.
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Infradian rhythms support the evolutionary theory
A03: Ultradian and Infradian Rhythms
Evolutionary psychologists claim that the synchronised menstrual cycle provides an evolutionary advantage for groups of women, as the synchronisation of pregnancies means that childcare can be shared among multiple mothers who have children at the same time.
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What are Endogenous Pacemakers?
A01: Endogenous Pacemakers and Exogenous Zeitgebers
Endogenous pacemakers are internal mechanisms that govern biological rhythms such as the circadian sleep-wake cycle
They can be affected by environmental cues as well, but they can function without these environmental cues.
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Give an example of Endogenous Pacemakers.
A01: Endogenous Pacemakers and Exogenous Zeitgebers
The suprachiasmatic nucleus (SCN), which lies in the hypothalamus, is the main endogenous pacemaker (or master clock).
The SCN receives information about light levels (an exogenous zeitgeber) from the optic nerve, which sets the circadian rhythm so that it is in synchronisation with the outside world, e.g. day and night.
The SCN signals the pineal gland which triggers the release of melatonin. Melatonin levels increase at night to bring on drowsiness and decrease with light to promote wakefulness. The SCN is regulated by light from the environment.
Thus, The SCN and pineal glands work together as endogenous pacemakers
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What are exogenous zeitgebers?
A01: Endogenous Pacemakers and Exogenous Zeitgebers
Cues from the environment play and plays a role in regulating time and the body's circadian rhythms.
This helps the body to synchronise with the environment.
Sunlight (most important) and social cues are exogenous zeitgebers or cues from the from the environment which affect body rhythms.
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Provide two examples of Exogenous Zeitgebers.
A01: Endogenous Pacemakers and Exogenous Zeitgebers
The SNC contains receptors that are sensitive to light and this external cue is used to synchronise the body’s internal organs and glands
Often the body adjusts to be in line with the environment, a process called entrainment. An example of when this occurs is when people travel across time zones resulting in jet lag at first as their body clocks are not synchronised with the environment, eventually adjusting over time, overcoming jet lag.
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Blue light
A03: Endogenous Pacemakers and Exogenous Zeitgebers
As we known the psychological effects of exposure to light (an exogenous zeitgeber), particularly blue light, can disrupt our natural melatonin levels making our bodies think it is daytime when it is not, thus disrupting our circadian rhythms.
This understanding of the effects of exogenous zeitgebers such as light on biological rhythms such as the sleep-wake cycle is a strength because research into the connection between blue light and sleep has allowed psychologists to provide people with advice on how to maintain a healthy sleep pattern such as by avoiding blue light at least two to three hours before sleep to ensure a healthy circadian rhythm is maintained.
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Support for the existence of exogenous zeitgebers --> Blind People
A03: Endogenous Pacemakers and Exogenous Zeitgebers
Skene and Arendt (2007) claimed that the majority of blind people who still have some light perception have normal circadian rhythms whereas those without any light perception show abnormal circadian rhythms. This demonstrates the importance of exogenous zeitgebers (such as light) as a biological mechanism and their impact on biological circadian rhythms.
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A strength of the study of exogenous zeitgebers, particularly light, is its application to avoiding jet lag.
But, how does this also benefit our economy positively?
(2 marks)
A03: Endogenous Pacemakers and Exogenous Zeitgebers
Burgess et al (2003) found that exposure to bright light prior to an east-west flight decreased the time needed to readjust to local time on arrival.
Participants exposed to continuous bright light shifted their circadian rhythm by 2.1 hours over the course of the study, and as a result, were brought closer to the local time conditions such that they would not experience jet lag.
This is a strength because it demonstrates the power of exogenous zeitgebers and their utility in our everyday experiences.
Furthermore, this research is particularly important for those who may fly frequently, for example, nurses. This is beneficial because it has real-life economic implications as research into the application of exogenous zeitgebers such as light can help increase productivity and efficiency, positively impacting the economy.
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Research support from animal studies about the significance of SCN.
A03: Endogenous Pacemakers and Exogenous Zeitgebers
The importance of the SCN has been demonstrated in research. Morgan (1955) bred hamsters so that they had circadian rhythms of 20 hours rather than 24.
SCN neurons from these abnormal hamsters were transplanted into the brains of normal hamsters, which subsequently displayed the same abnormal circadian rhythm of 20 hours, showing that the transplanted SCN had imposed its pattern onto the hamsters.
This research demonstrates the significance of the SCN and how endogenous pacemakers are important for biological circadian rhythms.
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Research findings from hamsters cannot be generalised to human understanding of endogenous pacemakers...
A03: Endogenous Pacemakers and Exogenous Zeitgebers
However, this research is flawed because of its use of hamsters. Humans would respond very differently to manipulations of their biological rhythms, not only because we are different biologically, but also because of the vast differences between environmental contexts.
This makes research carried out on other animals unable to explain the role of endogenous pacemakers
in the biological processes of humans.
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How do exogenous zeitgebers influence infradian rhythms e.g. menstrual cycle?
A03: Endogenous Pacemakers and Exogenous Zeitgebers
Research support suggests that the menstrual cycle is, to some extent, governed by exogenous zeitgebers (external factors).
Reinberg (1967) examined a woman who spent three months in a cave with only a small lamp to provide light. Reinberg noted that her menstrual cycle shortened from the usual 28 days to 25.7 days.
This result suggests that the lack of light (an exogenous zeitgeber) in the cave affected her menstrual cycle, and therefore this is a strength as it demonstrates the effect of external factors on infradian rhythms.
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Research support from Siffre's case study.
A03: Endogenous Pacemakers and Exogenous Zeitgebers
There is further research support for the role of exogenous zeitgebers.
When Siffre returned from an underground stay with no clocks or light, he believed the date to be a month earlier than it was.
This suggests that his 24-hour sleep-wake cycle was increased by the lack of external cues, making him believe one day was longer than it was. This highlights the impact of external factors on bodily rhythms.
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Research support the role of exogenous zeitgebers on the regulation of the sleep/wake cycle.
A03: Endogenous Pacemakers and Exogenous Zeitgebers
Murphy et al (1998) demonstrated that light may be detected by skin receptor sites on the body even when the same information is not received by the eyes.
Fifteen participants were woken at various times and a light pad was shone on the back of their knees. As such, the researchers managed to produce a deviation in the participant's usual cycle of up to 3 hours.
This suggests that light is a powerful exogenous zeitgeber that can extend its influence so greatly that it does not require detection by the eyes.
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Has not been replicated and has methodological issues.
A03: Endogenous Pacemakers and Exogenous Zeitgebers
However, these findings have yet to be replicated and so we cannot conclude that they are reliable.
Furthermore, the study has been methodologically criticised under the suggestion that there may have been light exposure to the participant's eyes, acting as a confounding variable which limits the internal validity of the study.
This limits the support that the research can give to the importance of exogenous zeitgebers.
