Ways of Studying the Brain: Scanning Techniques, including Functional Magnetic Resonance Imaging (fMRI); Electroencephalogram (EEGs) and Event-Related Potentials (ERPs); Post-Mortem Examinations

AO1: Ways of Studying the Brain

The brain is the main focus of neuroscience. Studying the brain gives us important insights into the underlying foundations of our behaviour and mental processes. A variety of methods are used by scientists in order to study the different areas and functions of the brain. Some involve scanning the living brain, looking for patterns of electrical activity associated with performance of particular tasks. Other methods involve studying sections of a deceased brain to investigate anatomical reasons for behaviour observed when the patient was alive.

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(1) AO1: Scanning Techniques:
(a) AO1: Functional Magnetic Resonance Imagining (fMRI):
Ӣ A technique for measuring changes in brain activity while a person performs a task.
Ӣ Does this by measuring changes in blood flow in particular areas of the brain (indicates increased neural activity in those areas).
Ӣ If a particular area of the brain become more active, there is increased demand for oxygen in that area.
Ӣ The brain responds to this extra demand by increasing blood flow, delivering oxygen in the red blood cells.
Ӣ As a result of these changes in blood flow, researchers are able to produce maps showing which areas of the brain are involved in a particular mental activity.

Example of when an FMRI can might be used in research: In memory research, Psychologists might as a participant to recall a list of words previously learned (prior to their scan). Such a task can inform Psychologists about the areas of the brain used in memory recall, therefore helping them to understand what parts of the brain are responsible for Long Term Memories (LTMs).

AO3: Evaluation of FMRI Scans:

Strengths:

(1) Point: fMRI scans can be praised for being non-invasive. Example/Evidence: For example, it does not involve the insertion of any instruments into the body, not does it exposed the brain to potentially harmful radiation as is the case with some other scanning techniques. Elaboration: This is a strength because it means that individual’s behaviours can be investigated without their physical, mental or psychological health being placed at risk.

(2) Point: fMRI offers a more objective and reliable measure of psychological process than is possible with verbal reports. Example/Evidence: For example, blood volume can be accurately measured to see which parts of the brain are being utilised in certain tasks, research using fMRI scans are bot simply relying on observations of participant behaviour or self-reports from participants themselves. Elaboration: This is a strength because it means that fMRIs are a useful way of investigating psychological phenomena that people would not be capable of providing in verbal reports whilst also removing any chances of bias (from observations/self-reports).

Weaknesses:

(1) Point: fMRIs are not a direct measure of neural activity in particular brain areas.
Example/Evidence: For example, fMRIs only measure changes in blood flow in the brain which makes interpreting fMRI scans high complex. Elaboration: This is a weakness because it is not a truly quantitative measure of mental activity in these brain areas.

(2) Point: The sample sizes from fMRI research are often small/unrepresentative. Example/Evidence: For example, research usually has a limited amount of funding and using fMRI scans often requires lots of money (for up keep of the machines, training for researchers to learn how to effectively use the machines). Elaboration: This is a weakness because this makes the research difficult to generalise/gives research low population validity.

(b) AO1: Electroencephalogram (EEG):

Ӣ Measure electrical activity in the brain.
Ӣ Electrodes (placed on the scalp) detect small electrical changes resulting from the activity of the brain cells.
Ӣ When electrical signals from the electrodes are graphed over a period of time, the resulting representation is called EEG.
”¢ EEG activity can be used to detect different types of brain disorders (e.g. epilepsy) or to diagnose other disorders that influence brain activity (e.g. Alzheimer’s disease).
Ӣ The four basic EEG patterns are; alpha (when a person is awake but relaxed), beta (when a person is physiologically aroused), delta and theta waves (both occur when a person is sleeping). When a person is moving from light sleep to deep sleep the occurrence of alpha waves decrease and are replaced firstly by theta and then delate waves.

AO3: Evaluation of EEG Techniques:

Strengths:

(1) Point: A strength of using EEG to measure brain activity is that it creates a measure of brain functioning in real time. Example/Evidence: For example, the EEG machine takes a reading of the active brain rather than a passive brain. Elaboration: This is a strength because the researcher can accurately measure a particular task or activity with the brain activity associated with it.

(2) Point: A strength of using EEG Machine is that they are useful when trying to make a clinical diagnosis. Evidence/Example: For example, epileptic seizures are caused by disturbed brain activity which means that the normal EEG reading suddenly changes. Elaboration: This is a strength because EEG machines can help to diagnose whether someone is experiencing epileptic seizures or other brain abnormalities.

Weaknesses:

(1) Point: A problem with using EEG readings/machines is that they can only detect activity in superficial regions of the brain. Example/Evidence: For example, the EEG canoe reveal what is going on in deeper regions of the brain such as the hypothalamus or hippocampus. Elaboration: This is a weakness because it means that the information gained from EEG machines about brain activity is often limited (unless more invasive procedures are used e.g. inserting electrodes into the brain to measure deeper brain activity).

(2) Point: A further weakness of using EEG is that the EEG signal is not useful for pinpointing the exact source of brain activity. Example/Evidence: For example, electrical activity in the brain can be picked up by several neighbouring electrodes. Elaboration: This is a weakness because the EEG does not allow researchers to distinguish between activities originating in different but closely adjacent locations of the brain.

(c)AO1:  Event Related Potentials (ERPs):

Ӣ ERPs are small voltage changes in the brain that are triggered by specific events or stimuli (E.G. cognitive processing of a specific stimulus).
Ӣ ERPs are difficult to pick out from all the other electrical activity being generated in the brain at a given time.
Ӣ To establish a specific response to a target stimulus requires many presentations of the stimulus and these responses are then averaged together.
”¢ Any extraneous neural activity that is not related to the specific stimulus will not occur consistently, whereas activity linked to the stimulus will. This has the effect of cancelling out the background neural ‘noise’, making the specific response to the stimulus stand out more clearly.
”¢ ERPs can be divided into two categories;                                                                              (1) Waves occurring in the first 100 milliseconds after presentation of the stimulus are termed ‘sensory ERPs’ as they reflect an initial response to the physical characteristics of the stimulus.

(2) ERPs generated after the first 100 milliseconds reflect the manner in which the participant evaluates the stimulus and are termed ‘cognitive ERPs’ as they are demonstrating information processing.

AO3: Evaluation of ERP’s:

Strengths:

(1) Point: A strength of using ERPs is that they produce a measure of processing in response to a continuous measure of processing in response to a particular stimulus. Example/Evidence: For example, during the presentation of different visual stimuli it is possible to see what part of the brain/neural activity is associated with processing that information. Elaboration: This is a strength because it makes it possible for researchers to determine how processing is affected by different stimuli and allows an insight to be gained into the functioning of the brain.

(2) Point: A strength of using ERPs is that it can measure the processing of a stimuli even in the absence of a behavioural response. Evidence/Example: For example, ERP recordings make it possible to monitor the processing of a particular stimulus without requiring a person to respond to them. Elaboration: This is a strength because ERP lead psychologists to develop a better understanding of the functioning of the brain.

Weaknesses:

(1) Point: A weakness of using ERPs is that the signal is not useful for pinpointing the exact source of brain activity. Evidence/Example: For example, electrical activity in the brain can be picked up by several neighbouring electrodes. Elaboration: This is a weakness because the ERP does not allow researchers to distinguish between activities originating in different but closely adjacent locations of the brain.

(2) Point: A further weakness of using ERPs is that the output can only be interpreted by a trained professional. Evidence/Example: For example, psychologists using ERPs require intense and expensive training in order to fully appreciate the activity measured from the ERP. Elaboration: This is a weakness because such training can increase the cost of research and with limited funding in specific research areas this can minimise the use of ERPs (attempting to save money).

(2) AO1: Post Mortem Examinations:

Ӣ Post Mortem examinations are used to establish underlying neurobiology of a particular behaviour (for example, researchers might study a person who display behaviours while they are alive that suggest possible underlying brain damage).
Ӣ Subsequently, when a person dies, the researcher can examine the brain of these individuals to look for abnormalities that might explained that behaviour (and which are not found in control individuals).
”¢ An early example of this was Broca’s work with his patient Tan, who displayed speech problems when he was alive was found to have lesions in the area of the brain that is now known to be the Broca’s area an important area for speech production.
”¢ Post Mortem examinations have also made it possible to identify some of the areas of the brain responsible for memory (e.g. HM’s inability to store new memories was linked to lesions in the hippocampus (Annese et al 2014)).
Ӣ The use of post-mortem studies has also been used to establish a link between psychiatric disorders (e.g. schizophrenia and depression) and underlying brain abnormalities.

AO3: Evaluation Post Mortem Examinations:

Strengths:

(1) Point: A strength of using Post Mortem examinations is that they allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with non-invasive scanning methods (e.g. fMRI/EEGs). Evidence/Example: For example, it enables researchers to examine deeper regions of the brain such as they hypothalamus and hippocampus. Elaboration: This is a strength because it allows psychologists to gain a deeper understanding of the role of the brain in human development, behaviour and abnormality.

(2) Point: Post Mortem examinations have played a central role in developing understanding of schizophrenia. Evidence/Example: For example, Harrison (2000) suggests that as a direct result of post mortem examinations, researchers have discovered structural abnormalities of the brain and have found evidence of neurotransmitters both which are associated with the disorder. Elaboration: This is a strength because gaining such knowledge has not only developed psychologists understanding of why schizophrenia develops, it also allows for the development of more successful treatments.

Weaknesses:

(1) Point: A weakness of Post Mortem examinations is that they can sometimes lead to inaccurate data and findings. Evidence/Example: For example, the length of time between death and Post Mortem examination, drug treatments and age of death are all confounding influences of any difference between case and controls. Elaboration: This is a weakness because the findings obtained from Post Mortem examinations may be criticised as lacking internal validity making it difficult for conclusions and cause and effect to be drawn.

(2) Point: A further weakness of using Post Mortem examinations is that the approach is retrospective.Evidence/Example: For example, due to the fact that the individual is already dead the researcher is unable to follow up anything that arises from the post mortem concerning a possible relationship between brain abnormalities and cognitive functioning. Elaboration: This is a weakness because it means that the conclusions that can be drawn from post mortem examinations are often limited.