Biopsychology : Ways of studying the brain Flashcards
Functional magnetic resonance imaging (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.
Electroencephalogram (EEG)
An electroencephalogram (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. EEG scanners measure this electrical activity through electrodes attached to the scalp. Small electrical charges are detected by the electrodes, and are graphed over a period of time, indicating the level of activity in the brain.
Event related potentials
Event-Related Potentials (ERP) use electrodes that are attached to the scalp, as with EEG. However, the key difference is that a stimulus is presented to a participant (for example a picture/sound) and the researcher looks for activity related to that stimulus.
What is post mortem examination?
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. An example of this technique is the work of Broca, who examined the brain of a man who displayed speech problems when he was alive.
Why do psychologist study the brain?
Studying the brain allows psychologist to gain important insight into the underlying foundations of our behaviour and mental processes
How to create deoxygenated haemoglobin
Energy requires glucose and oxygen. Oxygen is carried in the bloodstream attached to haemoglobin (found in red blood cells) and is released for use by these active neurons, at which point the haemoglobin becomes deoxygenated.
What does fMRI do?
- Deoxygenated haemoglobin has a different magnetic quality from oxygenated haemoglobin. An fMRI can detect these different magnetic qualities and can be used to create a dynamic (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. An increase in blood flow is a response to the need for more oxygen in that area of the brain when it becomes active, suggesting an increase in neural activity.
evaluation of fMRI
- 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.
- fMRI scans have good spatial resolution. Spatial resolution refers to the smallest feature (or 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.)
- 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 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.
What are the 4 types of EEG patterns?
including alpha waves, beta waves, theta waves and delta waves. Each of these patterns has two basic properties that psychologists can examine:
Amplitude: the intensity or size of the activity
Frequency: the speed or quantity of activity
What can EEG detect?
EEG can also be used to detect illnesses like epilepsy and sleep disorders, and to diagnose other disorders that affect brain activity, like Alzheimer’s disease.
What does ERP do?
ERPs are difficult to separate from all of the background EEG data, the stimulus is present many times (usually hundreds), and an average response is graphed. This procedure, which is called ‘averaging’, reduces any extraneous neural activity which makes the specific response to the stimulus stand out.
Evaluation of EEG & ERP
- An advantage of EEG and ERP is that both techniques are non-invasive. Unlike other scanning techniques, such as Positron Emission Tomography (PET), EEG and ERP do not use radiation or involve inserting instruments directly into the brain and are therefore virtually risk-free
-EEG and ERP are much cheaper techniques in comparison with fMRI scanning and are therefore more readily available.
- one disadvantage of EEG/ERP is that these techniques have poor spatial resolution. Spatial resolution refers to the smallest feature (or 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.
-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.
Evaluation of post mortem examination
Causation : - 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.
- 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.
-one strength of post-mortem examinations is that they provide a detailed examination of the anatomical structure and neurochemical aspects of the brain that is not possible with other scanning techniques (e.g. EEG, ERP and fMRI). 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.
Is fMRI invasive or non-invasive
Non-invasive
Is EEG invasive or non-invasive
Non-invasive ( although uncomfortable)
