ways of studying the brain

• Post-mortem examinations are when a person’s brain is examined in detail after-death to look for evidence of brain abnormalities.
• A strength of post-mortems is that a person’s brain can be examined at a very high level of detail, to identify very small brain abnormalities. Doctors can relate these abnormalities to the abnormal behaviours a patient displayed when they were alive. However, since we are looking at patient’s brains after death, we have no information about when the participant developed brain abnormalities. This makes it difficult to establish a cause and effect relationship
• Difficult to control extraneous or confounding variables. The lack of ability to control extraneous or confounding variables in post-mortem examinations, such as medication the participant may have taken that could affect the brain, makes it even harder to establish a cause and effect relationship between the brain abnormality and abnormal behaviour.
• fMRI stands for functional Magnetic Resonance Imaging. fMRI scans show the structure of the brain and generate an image of the inside of a person’s brain.
• fMRI measures changes in brain activity across the brain.
• If neurons in a particular brain region start sending lots of nerve impulses to each other, then activity increases in that brain region and so the brain needs more oxygen. When there is more electrical activity in a brain region, more oxygen is needed, so blood flow increases.
• fMRI measures the changes in blood flow that occur across parts of the brain while people perform tasks. fMRI works because, the more active a brain region is, the more oxygen it needs and so the more blood flows towards that brain region.
• A strength of fMRI is that researchers can look at activity in the brain while people are behaving, meaning that we can look more closely at the relationship between brain activity and behaviour. This is positive as it allows us to look at the relationship more directly than with post-mortem.
• No way to establish cause and effect relationship between brain activity and a person's behaviour using fMRI
• fMRI measures blood flow to the brain, which changes on a much slower timescale than changes in neural activity. This means that fMRI measurements might not pick up all of the changes in neural activity going on in the brain, so might not provide an accurate measure of neural activity. This means that fMRI measurements might lack validity as a measure of neural activity.
• EEG stands for electroencephalogram. It is a technique used to measure neural activity in the brain.
• EEG detects electrical activity by placing electrodes on people’s scalps to pick up electrical activity from groups of neurons. An electrode can only pick up electrical signals from the cortex. A signal can only be detected by the electrode if enough cells generate electrical activity.
• Electrical activity is more likely to be detected by the EEG if there are more electrodes and a large number of active cells near the electrodes.
• A strength of EEG is that it allows us to directly measure neural activity in the brain generated by neurons in the cortex in comparison to other techniques.
• A strength of EEG is that it's good at detecting synchronised activity that occurs when people sleep or have seizures.
• A limitation of EEG is that it can only pick up electrical signal from the cortex and electrical signals picked up by electrodes are often small making them difficult to interpret and relate to actual behaviour. Also, there is no way to establish what neurons are generating the activity
• ERP stands for event-related potentials. ERPs are small electrical signals recorded using EEG that occur in response to the presentation of a stimulus.
• ERPs are detected by presenting a stimulus over repeated trials, and averaging the EEGs recordings across all of them.
• Impractical. ERP's require a large number of trials to obtain meaningful data as they are detected by presenting a stimulus over repeated trials and averaging the EEGs recordings across all of them. This is problematic as it is time-consuming
• ERP involves averaging EEG recordings across hundreds of trials to identify a small electrical signal associated with a particular stimulus.
• Spatial resolution is the level of detail at which our method allows us to examine the brain.
• Post-mortems have the highest spatial resolution as we look at the brain under the microscope, meaning that we can look at individual neurons and synapses, followed by fMRI. EEG & ERP have lowest spatial resolution
• EEG and ERP have the highest temporal resolution, followed by fMRI. Post-mortem examinations have no temporal resolution
• Temporal resolution is how precise measurements are with respect to time.