Ways of Studying the Brain Flashcards
Studying the Brain
Studying the brain allows psychologists to gain important insights into the underlying foundations of our behaviour and mental processes.
What are the Ways of Studying the Brain?
- Functional Magnetic Resonance Imaging (fMRI)
- Electroencephalogram (EEG)
- Event-Related Potential (ERP)
- Post-Mortem Examination
- 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.
Energy requires glucose and oxygen. Oxygen is carried in the bloodstream, attached to haemoglobin (found in the red blood cells) and is released for use by these active neurons, at which point the haemoglobin becomes deoxygenated.
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 shows activity approximately 1-4 seconds after it occurs and is 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.
Strength - fMRI
Point: An advantage of fMRI is that it is non-invasive, making it a safer alternative to other scanning techniques.
Evidence: Unlike Positron Emission Tomography (PET), fMRI does not use radiation or require the insertion of instruments into the brain, reducing potential risks associated with the procedure.
Justification: Because fMRI is non-invasive, it minimises harm to participants, making it more ethical and suitable for a wide range of individuals, including those who might be at risk from radiation exposure or surgical procedures required by other methods. This is particularly beneficial in research where participant safety is a priority.
Implication: As a result of its non-invasive nature, fMRI can be used with more patients, allowing for a larger sample size in studies. This could lead to a deeper, more insightful understanding of the brain’s functioning, including the localisation of brain functions, and may aid in the development of more effective treatments for neurological disorders.
Strength - fMRI
Point: fMRI scans offer high spatial resolution, which is a significant advantage when studying brain activity.
Evidence: Spatial resolution refers to the smallest feature or measurement a scanner can detect. fMRI scans have a spatial resolution of approximately 1-2 mm, which is significantly better than other techniques like EEG or ERP, which typically have a lower spatial resolution.
Justification: The high spatial resolution of fMRI allows for precise localisation of brain activity, enabling psychologists to discriminate between smaller, closely situated brain regions with greater accuracy. This level of detail is particularly useful for understanding the specific functions associated with different areas of the brain.
Implication: The superior spatial resolution of fMRI makes it a valuable tool for investigating brain activity, as it provides more accurate data on which brain regions are involved in various cognitive processes. This can enhance our understanding of brain function and localisation, leading to more targeted interventions in clinical settings for conditions, such as brain injuries or neurological disorders.
Weakness - fMRI
Point: A limitation of fMRI scans is their poor temporal resolution, which affects the precision of detecting brain activity over time.
Evidence: Temporal resolution refers to how accurately a scanner can detect changes in brain activity over time. fMRI scans have a temporal resolution of 1-4 seconds, which is relatively slow compared to other techniques like EEG or ERP, which can measure brain activity in 1-10 milliseconds.
Justification: This limited temporal resolution means that fMRI scans cannot detect rapid, real-time fluctuations in brain activity with high accuracy. As a result, they are less effective for studying fast or transient cognitive processes, such as those involved in perception, attention, or decision-making, where millisecond-level precision is crucial.
Implication: This is a limitation of fMRI as it reduces the technique’s ability to accurately predict or measure the onset of brain activity. Consequently, it may not be suitable for research on brain functions that require high temporal precision, making it less reliable for certain types of cognitive and neuropsychological studies when compared to methods like EEG and ERP.
Weakness - fMRI
Point: A limitation of fMRI scans is that they do not provide a direct measure of neural activity, making it difficult to establish causal relationships at the neural level.
Evidence: fMRI scans detect changes in blood flow, which are assumed to correlate with brain activity. However, this indirect measure of neural activity does not directly capture the firing of neurons, meaning that changes in blood flow do not necessarily indicate the exact cause or specific function of the brain region being examined.
Justification: This lack of direct measurement of neural activity makes it challenging to draw definitive conclusions about causality. While changes in blood flow may suggest that a particular brain area is active, psychologists cannot conclusively determine whether the observed activity in that region is the cause of a specific behaviour or cognitive function, or if it is simply correlated with it.
Implication: This reduces the validity of fMRI as a tool for determining causal relationships in brain research. Without direct evidence of neural activity, psychologists may face difficulties in linking specific brain regions to particular functions, therefore limiting the accuracy of fMRI in establishing clear cause-and-effect conclusions.
- 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 detected by the electrodes are graphed over a period of time, indicating the level of activity in the brain.
There are four types of EEG patterns including alpha waves, beta waves, theta waves and delta waves. Each of these patterns has two basic properties that psychologists examine:
- Amplitude: the intensity or size of activity
- Frequency: the speed or quantity of activity
Furthermore, EEG patterns produce two distinctive states: synchronised and desynchronised patterns. A synchronised pattern is where a recognised waveform (alpha, beta, theta and delta) can be detected, whereas a desynchronised pattern is where no pattern can be detected.
Fast desynchronised patterns are usually found when awake and synchronised patterns are typically found during sleep (alpha waves are associated with light sleep, and theta/delta waves are associated with deep sleep). In addition, EEG scanning was responsible for developing our understanding of REM sleep, which is associated with a fast, desynchronised activity, indicative of dreaming.
EEGs 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.
- Event-Related Potential (ERP)
Event-Related Potentials (ERP) use similar equipment to EEG, electrodes attached to the scalp. However, the key difference is that a stimulus is presented to a participant, e.g., a picture or 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 presented 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.
The time or interval between the presentation of the stimulus and response is referred to as latency. ERPs have a very short latency and can be divided into two broad categories. Waves (responses) that occur within 100 milliseconds following presentation of a stimulus are referred to as sensory ERPs, as they reflect sensory response to the stimulus. ERPs that occur after 100 milliseconds are referred to as cognitive ERPs, as they demonstrate some information processing.
Strength - EEG and ERP
- Post-Mortem Examination
