The Brain

Question 1

What are the scanning techniques of studying the brain?

Answer 1

fMRI, EEG, ERPs and post-mortem examinations

Question 2

What is the process of fMRI?

Answer 2

-This technique works by measuring the changes in blood flow that occurs as the result of neural activity in specific parts of the brain.
-When the brain area is more active, it consumes more oxygen and the brain responds to this by increasing blood flow to the active area.
-The fMRI detects this change and produces a 3D moving image of the brain which highlights which area of the brain is involved in different tasks.

Question 3

What are the strengths of using fMRI scans?

Answer 3

1. Unlike many other scanning techniques, such as PET scans, it does not use potentially harmful radiation and is non-invasive so is virtually risk-free for the patient. This should allow more patients to undertake fMRI scans which could help psychologists to father further data on the functioning of human brain and develop our understanding of localisation.
2. It also has very high spatial resolution. Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy. fMRI scans have a spatial resolution of approx 1-2mm which is significantly greater than other techniques. This means the fMRI is capable of producing a very clear picture of how brain activity is localised.

Question 4

What are the limitations of using fMRI scans?

Answer 4

1. fMRI scans has poor temporal resolution. Temporal resolution refers to how quickly the scanner can detect changes in brain activity. fMRI scans have temporal resolution of 1-4 seconds which is worse than other techniques. Consequently, psychologists are unable to predict with a high degree of accuracy the onset of brain activity.
2. Carrying out fMRI scans is very expensive compared to other neuroimaging techniques as fMRI machines are very costly to buy and maintain, as well as requiring trained operators.

Question 5

What is the process of EEG?

Answer 5

-An EEG measures electrical activity in the brain.
-Electrodes are placed on the scalp using a scull cap.
-These detect and record electrical charges resulting from activity of brain cells.
-These signals are then graphed over a period of time, resulting in what is known as the EEG. EEGs are often used to detect various types of brain disorders such as epilepsy or Alzheimers as they are able to show abnormalities in the graph readings.

Question 6

What are the strengths of using EEG scans?

Answer 6

1. Unlike fMRIs, EEG technology has extremely high temporal resolution. Today’s technology can take readings which detect brain activity at a resolution of a single millisecond meaning it can record brain activity in real time. This leads to an accurate measurement of electrical activity when undertaking a specific task.
2. EEG machines is a much more cheaper technique in comparison with fMRI scanning and are therefore more readily available. Consequently, this should allow more patients to undertake EEG, which could help psychologists gather further data on the functioning of the human brain and therefore have a better understanding.

Question 7

What are the limitations of using EEG scans?

Answer 7

1. The main problem of EEGs is that it records the activity of the entire surface of the brain. This makes it very difficult to pinpoint the exact source of neural activity. EEGs are also only able to detect activity in the superficial regions of the brain, it cannot reveal what is going on in the deeper regions such as the hypothalamus.
2. Another problem with EEGs is that the caps are uncomfortable for the ppts as the electrodes are attached to the head. This could lead to unrepresentative readings and not gathering as much data as people won’t want to use it due to being uncomfortable.

Question 8

What is the process of ERPs?

Answer 8

-An ERP uses the same equipment as an EEG but measures a very small voltage changes in the brain that are triggered by specific stimuli or events.
-EEGs detect all neural activity being generated by the brain at a particular time so it is difficult to pick out the specific responses to the stimulus being presented.
-ERPs work by the ppt being presented with a stimulus many times and the numerous responses are then averaged together.
Any neural activity that is not related to the stimulus will not occur consistently whereas activity linked to the stimulus will and so the extraneous brain activity from the recordings can be filtered out, leaving only the responses that relate to the specific task.

Question 9

What are the strengths of ERP scans?

Answer 9

1. ERPs enable the determination of how processing is affected by a specific experimental manipulation. This makes ERP use a more experimentally robust method as it can eliminate extraneous neural activity. ERP, therefore being a much more specific measurement than could ever be achieved using raw EEG data.
2. As ERPs are derived from EEG measurements they also have excellent temporal resolution, especially when compared to neuroimaghing techniques such as fMRIs. This has led to their widespread use.

Question 10

What are the limitations of using ERP scans?

Answer 10

1. Critics have pointed to a lack of standardisation in methodology in different ERP studies which makes it difficult to confirm findings.
2. In order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated, which is not easy to do.

Question 11

What is the process of post-mortem examinations?

Answer 11

-Post-mortem exams are when a person’s body, including the brain is examined after they have died.
-In psychological research individuals who are subject to post-mortem are likely to be those who have experienced unusual behaviour or a rare disorder during their lifetime and the post-mortem is used to find any areas of damage as a way of establishing a likely cause.
-This may also involve a comparison with a typical brain to see the extent of the difference.

Question 12

What are the strengths of post-mortem examinations?

Answer 12

1. Post-mortem studies allow for more detailed examination of the brain than would be possible with the sole use of scanning techniques. They allow researchers to examine deeper regions of the brain such as the hypothalamus.
2. Post-mortem studies have played a central part in our understanding of schizophrenia. For example, as a direct result of post-mortems, researchers have found evidence of structural abnormalities of the brain associated with this order.

Question 13

What are the limitations of post-mortem examinations?

Answer 13

1. A problem with this approach is that the post-mortem brain may have been affected/changed by the reason of death. Therefore, the researchers may get invalid results.
2. This approach also raises ethical issues of consent from the patient before death. Patients may not be able to provide informed consent, e.g. in the case of HM who was unable to consent but still had post-mortem research conducted on his brain.

Question 14

Define localisation of function

Answer 14

The theory that different parts of the brain are responsible for different behaviours, processes or activities.

Question 15

Label the different lobes of the brain

Answer 15

https://o.quizlet.com/ZGCYneKRdZA3WMXtQN9Ksw_b.jpg

Question 16

What is the function of the motor cortex?

Answer 16

-The motor cortex is responsible for creating voluntary movements.
-It is located in the frontal love of both hemispheres, with the motor cortex on one side of the brain controlling muscles of the opposite side of the body.
-Motor function is highly localised, as different parts of the motor cortex control different parts of the body.

Question 17

What is the functions of the somatosensory cortex?

Answer 17

-Relates to sensations of the body. Using sensory information from the skin, the somatosensory cortex produces sensations of touch, pressure, pain and temperature.
-It is located in the parietal lobe of both hemispheres.
-The amount of the somatosensory cortex devoted to each body part is determined by how touch sensitive the area is.

Question 18

What is the function of the visual cortex?

Answer 18

-The visual cortex contains several different areas with each each processing different types of visual information, e..g colour, shape or movement.
-Each eye sends visual information to the opposite visual cortex, e.g from the right eye to the left visual cortex. This means that damage to the left hemisphere can cause blindness in part of the right visual field of both eyes.

Question 19

What is the function of the auditory cortex?

Answer 19

-The auditory centre is concerned with hearing.
-The auditory pathway begins in the cochlea in the inner ear where sound waves are converted to nerve impulses. These travel via the auditory nerve to the auditory cortex in the brain where it is recognised and may result in an appropriate response.

Question 20

What is the function of the languages areas of the brain?

Answer 20

Unlike other areas, language is restricted to only the left side of the brain.

Broca’s area - Responsible for speech production.
Wernicke’s Area- language comprehension (if damaged would result in Wernickes asphasia)

Question 21

What is the Broca’s area case study?

Answer 21

-Louis Victor Leborgne lost the ability to speak or speak in any matter that made any sort of sense.
-He could only utter a single syllable ‘tan’
-After Leborgne’s death, Broca conducted a post-mortem examination on his brain and discovered he had a lesion in the left frontal lobe.
-This led Broca to conclude that this area was responsible for his speech production. People with damage to the area experience Broca’s aphasia, which results in slow and inarticulate speech.

Question 22

What are the strengths of research on localisation of function?

Answer 22

There is lots of evidence to support the idea of localisation:

Evidence 1: Brain scan evidence - There is a huge amount of evidence from brain scans that support the idea that many brain functions are localised, particularly in relation to language and memory. For example, Peterson et al used fMRI scans to demonstrate how Wernicke’s area was activated during a listening task and Broca’s area was active during the speaking task. This strongly supports the idea that these areas of the brain have different functions.

Evidence 2: Neurosurgical evidence - Early attempts at the practice of surgically removing parts of the brain were brutal and imprecise. However, controversially they are still used rarely today in extreme causes of OCD and depression and provide evidence of localisation. For example, Dougherty reported on 44 OCD patients who had a procedure to create lesions of a part of their brain. At post-surgical follow-up after 32 weeks, 1/3 had met the criteria for successful response to the surgery. This suggests strong evidence that symptoms associated with mental disorders are localised.

Question 23

What are the limitations of research on localisation of function?

Answer 23

1. Not all researchers agree with the view that all brain functions are localised. Karl Lashley argues that whilst basic motor and sensory functions are indeed localised, higher mental functions were not. Lashley removed areas of the cortex (between 10 and 50%) in rats that were learning a maze. He found that no area of the brain was more important than an other in the rats ability to learn the maze. This appears to suggest that learning is too complex to be localised and requires the involvement of the whole brain.
2. A further conflicting theory is Lashley’s equipotentiality theory . Lashley claimed that if a specific part of the brain becomes damaged and a function is lost as a result, the rest of the brain appears to recognise itself in an attempt to recover that lost function. Although this doesn’t happen every time, this explanation has received some support from several cases of stroke victims who appear to regain functions that were thought to be lost due to the illness.

Question 24

What is lateralisation?

Answer 24

Refers to the fact that the 2 halves of the brain are not exactly alike and that certain mental processes and behaviours are controlled by one hemisphere rather than the other. This suggests that for most of us language is subject to what is called hemispheric lateralisation.

Question 25

What are split-brain studies?

Answer 25

These studies involve a group of epileptic patients who have had the two halves of their brain surgically separated in order to reduce their seizures. The result of this surgery is that information presented to one hemisphere of the brain can only be processed by that hemisphere. This provided psychologists with a unique opportunity to investigate the extent to which the brain is lateralised.

Question 26

How are split-brain studies done?

Answer 26

The patient focuses on a dot in the middle of a screen whilst an image or word is projected to their right and/or left visual field. They are given either a describe task, a tactile task or a drawing task.

In a normal brain, the corpus collosum would immediately share this information between both hemispheres to give a complete picture of the visual world but of course, this was not possible for the split-brain patients.

Question 27

What is the corpus collosum?

Answer 27

The bridge between the two hemispheres which connects them and allows them to communicate with each other.

Question 28

What was the conclusion of the split-brain studies?

Answer 28

When describing a task - When information was presented to the right visual field, the patient could describe what they saw, but information presented to the left visual field, the patient couldn’t describe what was shown. This shows the left hemisphere is responsible for language.

When doing a tactile task - When info was presented to the right visual field they could verbally describe what they felt or could identify the test object presented in the right hand, by selecting a similar appropriate object from a series of alternative. However, information presented to the left visual field could not describe what they felt and could only make wild guesses. However, the left hand cold identify objects. This means the left hemisphere dominates in speech.

Question 29

What are the strengths of split-brain research?

Answer 29

1. Split brain experiments made use of highly specialised and standardised procedures, e.g Sperry ensured that the image was presented to only one visual field for 1/10 of a second, making it impossible for the patient to move both eyes across the image. This allowed him to ensure that only one hemisphere was receiving information at a time.

Question 30

What are the limitations of split-brain research?

Answer 30

1. Sampling problems with split-brain research. Split brain procedures are now rarely conducted and so there is a problem with sample size in studies. Some research reports findings from as little as 3 or even just 1 ppt. There is also the issue that these ppts are sufferers of epilepsy so it is likely that there brains are not representative of a ‘normal brain’.
2. There were a number of problems with the way in which split-brain patients were studied which affected the validity of research, e.g: The disconnection between the brain hemispheres was greater in some patients than others. The control group were not considered valid as they were often people with no history of epileptic seizures so argued to be not comparable.

Question 31

What is plasiticity?

Answer 31

Refers to the brains ability to change and adapt both functionally and physically as a result of learning and experience.

Question 32

What is synaptic pruning?

Answer 32

During infancy, brain experiences a huge growth in the number of connections. As we age, rarely used connections are deleted and nerve pathways that are used frequently become stronger. This is known as synaptic pruning.

Question 33

What research evidence was done on plasticity?

Answer 33

Maguire et al (2000):
Aim - To examine whether structural changes could be detected tin the brain of people with extensive experience of spatial navigation.
Method - Structured MRI scans were obtained. 16 right-handed male London taxi drivers participated; all had been driving for more than 1.5 years. Scans of 50 healthy right-handed males who did not drive taxis were included for comparison. The mean age did not differ between any groups.
Results - Increased grey matter was found in the brains of taxi drivers compared with controls in two brain regions, the right and left hippocampus. The increased volume was found in the posterior hippocampus.
Conclusion: The results provide evidence for structural differences between the hippocampi of London taxi drivers and control ptts, therefore suggestions that extensive practice with spatial navigation affects of the hippocampus.

Question 34

What is a limitation of Maguire’s taxi study?

Answer 34

Maguire did not test the taxi drivers before they became taxi drivers, so it could be that ppts chose the job of taxi driver because they already had enlarged hippocampus areas, rather than the hippocampus changing as results of the job. Therefore, as a cause and effect relationship between experiences and changes in the brain cannot be clearly identified, further research into plasticity is necessary.

Question 35

What is an example of plasticity?

Answer 35

An example of this would be functional recovery - this is where, following an accident or injury, unaffected areas of the brain are often able to adopt and compensate (take over the function of areas that are damaged).

Question 36

How does functional recovery happen?

Answer 36

Where the brain is able to rewire and reorganise itself by a process known as neuronal unmasking - where ‘dormant’ synapses close to the area that had been damaged, open new connections and become activated. This process is supported by a number of other structural changes, e.g:
axonal sprouting - new axon terminals grow at the damaged site and connect to other undamaged nerve endings

recruitment of homologous areas on the opposite side of the brain - the opposite side of the brain take on the function of damaged area.

Question 37

What are the strengths of research on plasticity and functional recovery?

Answer 37

1. There is much support for plasticity and functional recover from animal studies e.g Kempermann et al found an increased number of neurons in the brains of rats housed in laboratory cages. In particular, the rats housed in the complex environment showed an increase in the neurons in the hippocampus. This supports brain plasticity because it shows that brains can change and adapt in response to experience.
2. Further evidence - Hubel & Wiesel - This involved sewing one eye of a kitten shut and analysing the brains response. It was found that the area of the visual cortex associated with the shut eye was not inactive but continued to process visual information from the open eye. This suggested that a kitten’s brain could adapt after damage, providing evidence for neueroplasticity.

Question 38

What are the limitations of research on plasticity and functional recovery?

Answer 38

1. There are also individual differences in the effectiveness of functional recovery. For example, Schneider found that patients with an equivalent of a college education were 7 time more likely that those who didn’t finish high school to be disability-free one year after a moderate to severe brain trauma. They concluded that ‘cognitive reserve’ could be a factor in the brains ability to adapt following brain injury. This suggests that individuals with a lower level of education are less likely to achieve full recovery.
2. The brains ability to rewire itself can have negative consequences, e.g prolonged drug use has been shown to result in poorer cognitive functioning and increased risk of dementia. Also, 60-80% of amputees have been known to develop phantom limb syndrome. These sensations are often painful and unpleasant and are thought to be due to cortical reorganisation in the somatosensory cortex.