Studying the brain

• studying the brain - intro


  Studying the brain allows psychologists to gain important insights into the underlying foundations of our behaviour and mental processes. A range of methods are available that involve scanning the living brain, and looking at patterns of electrical activity. However, a post-mortem examination is another possible approach.
• FMRI


  Functional magnetic resonance imaging (fMRI) is a brain-scanning technique that measures blood flow in the brain when a person performs a task. fMRI works on the premise that neurons in the brain that are the most active during a task use the most energy. detects magnetic qualities and can be used to create a moving 3D map of the brain, highlighting which areas are involved in different neural activities. fMRI images show activity approximately 1-4 seconds after it occurs and are thought to be accurate within 1-2 mm.
• FMRI strength:


  An advantage of fMRI is that is non-invasive. Unlike other scanning techniques, for example Positron Emission Tomography (PET), fMRI does not use radiation or involve inserting instruments directly into the brain, and is therefore virtually risk-free. Consequently, this should allow more patients/participants to undertake fMRI scans which could help psychologists to gather further data on the functioning human brain and therefore develop our understanding of localisation of function.
• FMRI strength: 


  good spatial resolution (the smallest feature/measurement that a scanner can detect and is an important feature of brain scanning techniques) Greater spatial resolution allows psychologists to discriminate between different brain regions with greater accuracy. fMRI scans have a spatial resolution of approximately 1-2 mm which is significantly greater than the other techniques (EEG, ERP, etc.) Consequently, psychologists can determine the activity of different brain regions with greater accuracy when using fMRI, in comparison to when using EEG and/or ERP.
• FMRI limit:


  fMRI scans have poor temporal resolution. Temporal resolution refers to the accuracy of the scanner in relation of time: or how quickly the scanner can detect changes in brain activity. fMRI scans have a temporal resolution of 1-4 seconds which is worse than other techniques (e.g. EEG/ERP which have a temporal resolution of 1-10 milliseconds). Consequently, psychologists are unable to predict with a high degree of accuracy the onset of brain activity.
• FMRI limit:


  fMRI scans do not provide a direct measure of neural activity. fMRI scans simply measure changes in blood flow and therefore it is impossible to infer causation (at a neural level). While any change in blood flow may indicate activity within a certain brain area, psychologists are unable to conclude whether this brain region is associated with a particular function.
• EEG: 


  works on the premise that information is processed in the brain as electrical activity in the form of action potentials or nerve impulses, transmitted along neurons.

  Fast desynchronized patterns are usually found when awake and synchronised patterns are typically found during sleep. Furthermore, EEG scanning was responsible for developing our understanding of REM (dream) sleep, which is associated with a fast, desynchronized activity, indicative of dreaming. used to detect illnesses like epilepsy and sleep disorders.
• ERPs

  use similar equipment to EEG, electrodes attached to scalp. but, difference is that a stimulus is presented to a ppt (e.g. picture/sound) and the researcher looks for activity related to that stimulus. However, as ERPs are difficult to separate from all of the background EEG data, the stimulus is present many times, and average response is graphed. This procedure reduces any extraneous neural activity which makes the specific response to the stimulus stand out. have a very short latency and can be divided into two broad categories- occur within 100 milliseconds
• strength: EEG and ERPs


  techniques are non-invasive. Unlike other scanning techniques (PET), EEG + ERP dont use radiation/ involve inserting instruments directly into the brain and therefore virtually risk-free. also, EEG and ERP are cheaper techniques in comparison with fMRI scanning + are therefore more readily available. Consequently, this should allow more patients/ppts to undertake EEG/ERPs, which may help psychologists to gather further data on functioning human brain + therefore develop our understanding of different psychological phenomena, such as sleeping + disorders like Alzheimer's
• limit: EEG and ERPs


  techniques have poor spatial resolution (spatial resolution = the smallest feature/measurement that a scanner can detect, and is an important feature of brain scanning techniques)- allows psychologists to discriminate between different brain regions with greater accuracy. EEGs/ERPs only detect the activity in superficial regions of the brain. Consequently, EEGs and ERPs are unable to provide information on whats happening in the deeper regions of the brain (e.g. hypothalamus), making this technique limited in comparison to the fMRI, which has a spatial resolution of 1-2mm.
• strength: EEG and ERPS


  An advantage of the EEG/ERP technique is that it has good temporal resolution: it takes readings every millisecond, meaning it can record the brain’s activity in real time as opposed to looking at a passive brain. This leads to an accurate measurement of electrical activity when undertaking a specific task
• limit: EEG and ERPs:


  However, it could be argued that EEG/ERP is uncomfortable for the participant, as electrodes are attached to the scalp. This could result in unrepresentative readings as the patient’s discomfort may be affecting cognitive responses to situations. fMRI scans, on the other hand, are less invasive and would not cause the participants any discomfort, leading to potentially more accurate recordings.
• EEG limit:


  Another issue with EEG is that electrical activity is often detected in several regions of the brain simultaneously. Consequently, it can be difficult pinpoint the exact area/region of activity, making it difficult for researchers to draw accurate conclusions.
• ERPs strength:


  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 neutral activity, something that other scanning techniques (and EEG) may struggle to do.
• post-mortem technique:


  on dead person - researchers will study the physical brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage (e.g. Broca's + Wernicke's area) - method of investigation has contributed to understanding many disorders
• post mortem: limit


  One of the main limitations of post-mortem examination is the issue of causation. The deficit a patient displays during their lifetime (e.g. an inability to speak) may not be linked to the deficits found in the brain (e.g. a damaged Broca’s area). The deficits reported could have been the result of another illness, and therefore psychologists are unable to conclude that the deficit is caused by the damage found in the brain.
• post-mortem: limit


  In addition, another issue is that there are many extraneous factors that can affect the results/conclusions of post-mortem examinations. For example, people die at different stages of their life and for a variety of different reasons. Furthermore, any medication a person may have been taking, their age, and the length of time between death and post-mortem examination, are all confounding factors that make the conclusions of such research questionable.
• post-mortem: limit


  while they're ‘invasive’, this isnt an issue bc the patient is dead. but, there are ethical issues in relation to informed consent and whether or not a patient provides consent before their death. Furthermore, many post-mortem examinations are carried out on patients with severe psychological deficits (e.g. patient HM who suffered from severe amnesia) who would be unable to provide fully informed consent, and yet a post-mortem examination has been conducted on his brain. This raises severe ethical questions surrounding the nature of such investigations.
• post-mortem limit:


  Post-mortem examinations can access areas like the hypothalamus and hippocampus, which other scanning techniques cannot, and therefore provide researchers with an insight into these deeper brain regions, which often provide a useful basis for further research. For example, Iverson found a higher concentration of dopamine in the limbic system of patients with schizophrenia which has prompted a whole area of research looking into the neural correlates of this disorder.
• FMRI:


  fMRI measures blood flow when a person performs a task and creates a dynamic (moving) 3D map of the brain, highlighting which areas are involved in different neural activities.

  Non-Invasive

  Temporal resolution = 1-4 s

  Spatial resolution = 1-2 mm
• EEG:


  EEG measures electrical activity through electrodes attached to the scalp. Small electrical charges are detected by the electrodes that are graphed over a period of time, indicating the level of activity in the brain.

  Non-Invasive (although uncomfortable)

  temporal resolution = 1-10 ms

  spatial resolution = Superficial general regions only
• ERP:


  ERP uses similar equipment to EEG. However, the key difference is that a stimulus is presented to a participant and the researcher looks for activity related to that stimulus.

  Non-Invasive (although uncomfortable)

  temporal resolution = 1-10 ms

  spatial resolution = Superficial general regions only
• post-mortem:


  A post-mortem examination is when researchers study the physical brain of a person who displayed a particular behaviour while they were alive that suggested possible brain damage.

  Invasive - although the person is no longer alive

  temporal and spatial resolution = N/A