ways of studying the brain

fMRI (functional magnetic resonance imaging)

-technique for measuring changes in brain activity while a person performs a task.

I-by measuring changes in blood flow in particular areas of the brain (indicates increased neural activity in those areas)

-If a particular area becomes more active, there is increased demand for oxygen in that area

-The brain responds to this extra demand by increasing blood flow, delivering oxygen in the red blood cells

- 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 might be used in research:

in memory research, psychologists might ask 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)

strengths of fMRIs

-non-invasive

-very high spatial resolution

-more objective and reliable measure of psychological processes than is possible with verbal reports

fMRI strength: non-invasive

 fMRI scans can be praised for being non-invasive (eg it does not involve the insertion of any instruments into the body, nor does it expose the brain to potentially harmful radiation as is the case with other scanning techniques. Strength because it means that individual’s behaviours can be investigated without their physical, mental or psychological health being placed at risk.

fMRI strengths: objective and reliable

fMRI offers a more objective and reliable measure of psychological processes than is possible with verbal reports. As blood volume can be accurately measured to see which parts of the brain are being utilised in certain tasks, research using fMRI scans are superior to both simply relying on observations of participant behaviour or self-reports from participants themselves. Strength because it means 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).

(strength of all brain scans)

fMRI strength: high spatial resolution

 fMRI produces images that have very high spatial resolution, depicting activity by the cubic millimetre. This is a strength as it allows for detailed analysis of the location of neural activity to be conducted. It can also access inner regions of the brain.

fMRI: weaknesses

-not direct measure of brain activity

-small/unrepresentative sample size

-poor temporal validity/ accuracy with time

fMRI weakness: not direct measure of brain activity

fMRIs are not a direct measure of neural activity in particular brain areas. For example, fMRIs only measure changes in blood flow in the brain which makes interpreting fMRI scans high complex. Weakness because it is not a truly accurate measure of mental activity at an individual neuronal level

fMRI weakness: small/unrepresentative sample size

 the sample size from fMRI research are often small/ unrepresentative. For example, research has limited amount of funding and using fMRI scans often requires lots of money (for upkeep of the machines, training for researchers to learn how to effectively use the machines). Weakness because this makes the research difficult to generalise/gives research low population validity

fMRI weakness: poor temporal validity/ accuracy with time

 fMRI has a poor temporal resolution. This means that it takes approximately five seconds for the image to appear since the actual neural activity took place. 

EEG (electroencephalogram)

-measures electrical activity in the brain.

-Electrodes (placed on the scalp) detect small electrical changes from the activity of the neurons. 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)

-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 to deep sleep the occurrence of alpha waves decreases and are replaced firstly by theta and then delta waves

EEG: strengths (2)

-high temporal validity (measure of brain functioning in real time)

-useful to make clinical diagnosis

EEG strengths: high temporal validity

it creates a measure of brain functioning in real time. This is referred to as high temporal resolution. For example, the EEG machine takes a reading of the active brain rather than a passive brain. Strength because the researcher can accurately measure a particular task or activity with the brain activity associated with it

EEG strengths: useful to make clinical diagnosis

they are useful when trying to make a clinical diagnosis. For example, epileptic seizures are caused by disturbed brain activity which means that the normal EEG reading suddenly changes. Strength because EEG machines can help to diagnose whether someone is experiencing epileptic seizures or other brain abnormalities.

EEG: weaknesses (2)

-can only detect surface level activity of the brain

-not useful for pinpointing exact region of activity

(low spatial resolution for both points)

EEG weaknesses: only surface level detection

a problem with using EEG readings/machines is that they can only detect activity in superficial (surface level ) regions of the brain. For example the EEG cannot reveal what is going on in deeper regions of the brain such as the hypothalamus or hippocampus. Weakness because it means thar 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

EEG weaknesses: can’t pinpoint exact region

 EEg signal is not useful for pinpointing the exact source of brain activity. Foir example, electrical activity in the brain can be picked up by several neighboring electrodes. Weakness because the EEG does not allow researchers to distinguish between activities originating in different but closely adjacent locations of the brain. 

ERP (event related potentials)

-ERP’s are small voltage changes in the brain that are triggered by specific events or stimuli (e.g cognitive processing of a specific stimulus). Erp’s are difficult to pick out from all the other electrical activity being generated in the brain at a given time. To establish a specific response to a target stimulus requires that previous EEG average readings are used as a comparison, the ERP should show as a change or difference against this average reading. Any extraneous neural activity linked to the stimulus will not be. This has the effect of cancelling out the background neural ‘noise’, making the specific response to the stimulus stand out more clearly.

ERP’s can be divided into two categories:

1- waves occurring in the first 100 milliseconds (0.1 seconds) after presentation of the stimulus are termed ‘sensory ERP’s’ as they reflect an initial response to the physical characteristics of the stimulus

2- ERP’s generated after the first 100 milliseconds (0.1 seconds) reflect thye manner in which the participant evaluates the stimulus and are termed ‘cognitive ERP’s’ as they are demonstrating information processing

-baseline without stimulus, any deviation with simulus shows cognitive activity

ERP strengths (2)

-produce a measure of processing in response to a particular stimulus

-can measure the processing of a stimuli even in the absence of a behavioural response

ERP strength: produce a measure of processing in response to a particular stimulus

they produce a measure of processing in response to a particular stimulus. For example, during the presentation of different visual stimulus it is possible to see what neural activity is associated with processing that information. This is known as high temporal resolution. This is a strength of because it makes it possible fo researchers to determine how processing is affected by different stimuli and allows an insight to be gained into the functioning of the brain

ERP strength: can measure the processing of a stimuli even in the absence of a behavioural response

a strength of using EWRP’s is that it can measure the processing of a stimuli even in the absence of a behavioural response. For example ERP recordings make it possible to monitor the processing of a particular stimulus without requiring a person to respond to them. This is a strength because ERP has led psychologists to develop a better understanding of the functioning of the brain

ERP weaknesses (similar to EEG)

-low spatial resolution

-can only be interpreted by a trained professional

ERP weakness: low spatial resolution

the signal is not useful for pinpointing exact source of brain activity. For example electrical activity in the brai can be picked up by several neighbouring electrodes. Also like EEgs part of of the inner brain are more difficult to measure, meaning that studying activity in the cortex is the most common use of this method. Weakness because the ERP does not allow researchers to distinguish between activities origionsting in different but closely adjacent locations of the brain (low spatial resolution)

ERP weakness: can only be interpreted by a trained professional

 the output can only be interpreted by a trained professional. For example, psychologists using ERP’s require intense and expensive training in order to fully appreciated the activity measures from the ERP. Weakness because such training can increase the cost of esearch and with limited funding in specific research areas this can minimise the use of ERP’s (attempting to save money)

Post-mortem examinations

-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).

-when a person dies, the researcher can examine the brain of these individuals to look for abnormalities that might explain that behaviour (and which are not found in control individuals)

-early example = Broca’s work with patient Tan, who displayed speech problems when he ws 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)

-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= neurochemical analysis (depression= serotonin, dopamine= schizophrenia)

Postmortem examinations strengths (2)

-allow detail, chemical and anatomical aspects

-vital to early psychological developments

Post-mortem strengths; detail, chemical, anatomical aspects

they allow for more detailed examination for anatomical and neurochemical aspects of the brain than would be possible with non-invasive scanning methods (EEGs) for example, it enables researchers to examine deeper regions of the brain such as the hypothalamus and hippocampus. Strength because it allows psychologists to gain a deeper understanding of the role of the brain in human development, behaviour and abnormality

post mortem strengths; vital to early development

played a central role in developing early understandings of brain functions. Paul Broca and Karl Wernicke both relied on post-mortems in establishing a link between language, brain and behaviour decades before neuroimaging ever became a possibility. Strength because it has improved medical knowledge and allowed further hypotheses to be proposed (eg localisation theory)

post-mortem weaknesses

-can leads to inacurate findings

-retrospective aproach

post-mortem weaknesses: inacurate findings

 they can sometimes lead to inaccurate data and findings. For example the length of time between death and post-mortems examination, drug treatment and age of death are all confounding influences of any difference between case and controls. 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 (no manipulation of variables)

post-mortem weaknesses: retrospective approach

the approach is retrospective. 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. Weakness because it means the conclusions that can be drawn up are limited