Ways of investigating the brain

• Post mortem examinations

  If a researcher suspects that a patient’s behavioural changes were caused by brain damage, they may look for abnormalities after the person dies.

  Example: Broca observed patients’ speech difficulties and found lesions in the brain post-mortem.
• Post mortem examinations

  H.M.’s brain has been extensively investigated post-mortem, confirming damage to his hippocampus related to his inability to store new memories.

  Post-mortem studies have also identified

   brain abnormalities in schizophrenia and 

  depression
• AO3 - Post mortems

  (+) brain tissues can be examined in detail and deeper structures can be investigated

  (+) changes in neurotransmitter levels can be measured eg. abnormalities associated with schizophrenia

  (-) use of drugs and age may affect brain tissue so there are many confounding variables

  (-) only retrospective data be collected. It is too late to test cognitive function.
• FMRI - Functional magnetic resonance imaging

  Measures changes in blood flow, indicating increased neural activity, in particular brain areas.

  Fmri are useful for identifying which areas of the brain are involved in particular mental activities.
• AO3 - FMRI

  (+) it is non invasive so it can be used to measure activity in the living brain without causing pain

  (+) it is more objective than relying on verbal reports of psychological processes. It is useful for studying non-verbal phenomena

  (-) it is not measuring neural activity directly so findings can be misinterpreted

  (-) it overlooks the networked nature of brain activity – may be more important than localised activity
• Electroencephalograms (EEG)

  Measure electrical activity in the brain via electrodes placed on the scalp. EGGS show brain waves over time.

  EEG patterns in patients with epilepsy show spikes of electrical activity.

  Alzheimer’s patients often show overall slowing of electrical activity
• Electroencephalograms

  EEGs are often used by clinicians as a diagnostic tool.

  This is because unusual arrhythmic patterns of activity (no particular rhythm)  may indicate neurological abnormalities such as epilepsy, tumours, or disorders of sleep.
• AO3 - EEG

  (+) it records brain activity in real time so researchers can monitor responses to task

  (+) it is useful for clinical diagnosis e.g epilepsy, seizures give characteristics EEG spikes

  (-) it can’t detect activity in deeper brain region such as the hippocampus

  (-) it can’t pinpoint the exact source of activity – as electrodes detect electrical activity from overlapping areas
• Event-related potentials (ERPs)

  EEGs are quite a basic and general form of looking at brain activity.

  ERPs are a way of teasing out and isolating specific neural responses associated with sensory, cognitive, and motor events. These are of interest to cognitive neuroscientists.
• ERPs

  ERPs work by using a statistical averaging techniques, that filters out extraneous brain activity from the original EEG recording, leaving only the responses that relate to say, the presentation of a specific stimulus or performance of a specific task.

  Event-related potentials remain; types of brainwave that are triggered by particular events.
• AO3 - ERPs

  (+) they provide a continuous measure of processing in response to a stimulus. This gives quantitative experimental data.

  (+) they can measure brain response without the need for behavioural response or speech. Researchers can “covertly” monitor responses

  (-) it requires many repetitions to gain meaningful data. So they address simple questions

  (-) they can only record voltage changes in superficial brain areas. So only event in the neocortex are measurable