Ways of investigating the brain

• fMRI detects changes in blood oxygenation and flow that occur as a result of neural activity in specific parts of the brain. When a brain area is more active it consumes more oxygen and to meet this increased demand, blood flow is directed to the active area.
• fMRI produces 3D images showing which parts of the brain are involved in a particular mental process and this has important implications for our understanding of localisation of function.
• EEGs measure electrical activity within the brain via electrodes that are fixed to an individual's scalp using a skull cap. The scan recording represents the brainwave patterns that are generated from the action of millions of neutrons, providing an overall account of brain activity.
• EEG is often used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity (no particular rhythm) may indicate neurological abnormalities such as epilepsy, tumours or disorders of sleep.
• EEG is an overly general measure of brain activity, however, within EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscientists. So researchers have developed a way of teasing out and isolating these responses.
• Using a statistical averaging technique, all extraneous brain activity from the original EEG recording is filtered out leaving only those responses that relate to a specific stimulus or task. What remains are event-related potentials (types of brainwaves that are triggered by particular events).
• Post-mortem examinations= a technique involving the analysis of a person's brain following their death.
• In psychological research, individuals whose brains are subject to a post-mortem examination are likely to be those with a rare disorder who have experienced unusual deficits in mental processes or behaviour during their lifetime.
• Areas of damage within the brain are examined after death as a means of establishing the likely cause of the affliction the person suffered. This may also involve comparison with a neurotypical brain in order to ascertain the extent of the difference.
• Unlike other scanning techniques, fMRI does not rely on the use of radiation. It is virtually risk-free, non-invasive and straightforward to use. It also produces images that have very high spatial resolution and provide a clear picture of how brain activity is localised.
• fMRI is expensive and can only capture a clear image if the person stays perfectly still.
• fMRI has poor temporal resolution because there is a 5 second time-lag behind the image on screen and the initial firing of neuronal activity.
• fMRI can only measure blood flow in the brain, it cannot home in on the activity of individual neurons and so it cane be difficult to tell exactly what kind of brain activity is being represented on screen.
• EEG is key in the diagnosis of conditions such as epilepsy and has contributed to our understanding of the stages involved in sleep.
• EEG has extremely high temporal resolution.
• The EEG signal is not useful for pinpointing the exact source of neural activity and it does not allow researchers to distinguish between activities originating in different but adjacent locations.
• Post-mortem evidence was vital in providing a foundation for early understanding of key processes in the brain. Broca and Wernicke both relied on post-mortem studies.
• Post-mortem studies improve medical knowledge and help generate hypotheses for further study.
• Observed damage in post-mortems may not be linked to the deficits under review but to some other unrelated trauma or decay.
• Post-mortem studies raise ethical issues of consent from the patient before death.