Ways of studying the brain

What is a post-mortem examination?

dissection and analysis of a person’s brain following their death

What are typical characteristics of a post-mortem examination? (3)

subjects are likely to have a rare disorder and have experienced unusual deficits in mental processes or behaviour in their life, areas of damage are studied to establish the likely cause of the affliction the person suffered, sometimes compared with a typical brain to determine the extent of the difference between them

What does EEG stand for?

electroencephalogram

What is an electroencephalogram?

measuring electrical activity within the brain via electrodes fixed to an individual’s scalp using a skull cap

What is the scan recording produced from an EEG? (4)

represents the brainwave patterns that are generated directly from electric activity, known as action potentials, of millions of neurons, providing an overall account of brain activity

Why is an EEG often used as a diagnostic tool?

unusual arrhythmic patterns of activity can indicate epilepsy, tumours or sleep disorders

What are the main types of EEG waves? (4)

alpha, beta, theta, delta

Which type of EEG wave has the highest frequency (speed or quantity of activity)?

beta

Which type of EEG wave has the largest amplitude (intensity or size of the activity)?

delta

What does ERP stand for?

event-related potentials

What is an event-related potential? (3)

action potentials related to an event, using the same equipment as EEGs, but using a particular technique

What technique is used in an event-related potential? (4)

baseline reading is taken from the participant using the EEG, stimulus is presented to the participant repeatedly, researcher looks for activity related to the stimulus or event, baseline data can be removed to find the precise reading from the brain for the specific event

How do ERPs use statistical averaging? (4)

the stimulus is presented hundreds of times and an average response can be graphed, removing the baseline response reduces any extraneous brain activity, so the specific response to the stimulus can stand out, as ERPs are shown to be linked to cognitive processes like attention and perception

What does fMRI stand for?

functional magnetic resonance imaging

What is the hemodynamic response?

blood flow is directed to the active area to meet the increased demand for oxygen

How does an fMRI work? (3)

fMRI detects changes in blood oxygenation and flow as a result of brain activity, oxygen carried to the brain by haemoglobin in red blood cells, when an area is more active it consumes more oxygen so more haemoglobin is present and blood flow increases

What does the fMRI scanner pick up? (2)

the change in the amount of oxygen in the blood affects the magnetic properties of the haemoglobin, the fMRI scanner picks up these differences creating an image

How do fMRI scans help to understand localisation of function?

they produce 3D images showing which parts of the brain are involved in particular mental processes

Which colour corresponds to oxygen levels in the image produced by an fMRI scanner? (3)

most oxygen is red, less oxygen is yellow, least oxygen is blue

What is the resulting image of an fMRI scanner?

it produces a map of activation for a particular task compared to a baseline of brain activity when not completing a task