Ways Of Investigating The Brain

• •There are four ways of investigating the brain that we need to know: fMRI, EEG, ERP, post-mortem examination.
• Ways Of Investigating The Brain

  •Due to advances in science and technology, we now have more sophisticated and precise ways of measuring the brain.•Some techniques record global neural activity and others hone in on activity in specific parts of the brain as it performs certain tasks or processes. Others involve studying sections of a deceased brain to investigate anatomical reasons for behaviour observed whilst the patient was alive.
• Functional magnetic resonance imaging (fMRI)

  A technique for measuring changes in brain activity while a person performs a task
• How fMRI works

  1. Measures changes in blood flow in particular areas of the brain using magnetic fields and radio waves

  2. Indicates increased neural activity in those areas (i.e. it's an indirect measure of neural activity in particular brain areas)

  3. 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 to deliver oxygen in red blood cells

  4. The amount of oxygenated blood in that part of the brain changes, and that has a magnetic signature which can be detected by fMRI

  5. Radio waves are used to reorient hydrogen atoms in the brain, the speed that they return to their original position is another measure of the amount of oxygenated haemoglobin in that part of the brain
• This allows researchers to produce maps showing which areas of the brain are involved in a particular mental activity
• fMRI research

  • Expensive when compared to other neuroimaging techniques
  • Reduced sample sizes which negatively impact the validity of the research
  • Can only capture a clear image if the person stays perfectly still
• fMRI

  • Captures dynamic brain activity
  • Advantageous to investigate brain activity in humans rather than generalising from animal lesion/single electrode recording studies (for validity and ethical reasons)
  • Virtually risk-free, non-invasive and straightforward to use
  • Produces images with high spatial resolution, depicting detail by the millimetre, and providing a clear picture of how brain activity is localised
  • Offers a more objective and reliable measure of psychological processes than is possible with verbal reports
• fMRI

  Measures changes in blood flow in the brain, not a direct measure of neural activity in particular brain areas
• fMRI is useful as a way of investigating psychological phenomena that people would not be capable of providing in verbal reports
• fMRI is not a truly quantitative measure of mental activity in these brain areas
• fMRI

  • Poor temporal resolution because there is around a 5-second time-lag behind the image on screen and the initial firing of neuronal activity
• fMRI overlooks the networked nature of brain activity as it focuses only on localised activity in the brain
• Communication among the different regions is most critical to mental function
• EEG


  •EEG is often used by clinicians as a diagnostic tool, as unusual arrhythmic patterns of activity (i.e. no particular rhythm) may indicate neurological abnormalities such as epilepsy, tumours, Alzheimer’s disease or disorders of sleep.•For example, EEG readings of patients with epilepsy show spikes of electrical activity. EEG patterns in patients with brain disease and brain injury show overall slowing of electrical activity.
• EEG

  Electroencephalogram - Measures electrical activity in the brain
• How EEG works

  1. Electrodes placed on scalp using skull cap

  2. Detect small electrical charges resulting from neuronal activity directly below

  3. Differing numbers of electrodes used depending on research focus
• EEG scan recording

  • Represents brainwave patterns generated from action of millions of neurons
  • Provides overall account of brain activity
• EEG

  Recording of general brain activity, usually linked to states such as sleep and arousal
• EEGs

  • High temporal resolution
  • Can accurately detect brain activity at a resolution of a single millisecond (and even less in some cases)
  • Researcher can accurately measure a particular task or activity with the brain activity associated with it
• EEGs

  Invaluable in clinical diagnoses
• EEGs

  • Epileptic seizures are caused by disturbed brain activity, which means that the normal EEG reading suddenly changes
• EEGs

  Useful way of helping to diagnose conditions, allowing people to access treatment
• EEGs

  • Much cheaper than fMRIs
  • Possible to use larger sample sizes
  • Results are more likely to be externally valid
  • Can be used more widely in research
• EEG Weakness - Eval

  The main drawback of EEGs is their poor spatial resolution. The EEG signal is not useful for pinpointing the exact source of neuronal activity because electrical activity can be picked up by several neighbouring electrodes. As a result, researchers are unable to distinguish between activities originating in different but adjacent locations of the brain.

  EEGs can only detect the activity in superficial regions of the brain. This means that it cannot reveal what is going on in the deeper regions of the brain such as the hypothalamus or hippocampus.
• EEG

  Recording of general brain activity usually linked to states such as sleep and arousal, a crude and overly general measure of brain activity
• Within the EEG data are contained all the neural responses associated with specific sensory, cognitive and motor events that may be of interest to cognitive neuroscientists
• Event-related potentials (ERPs)

  1. Statistical averaging technique

  2. Filter out extraneous brain activity

  3. Leaving only responses related to a specific stimulus presented to the participant
• To filter out the extraneous brain activity, many presentations of the specific stimulus and then the responses are averaged together
• Any extraneous neural activity won't occur consistently, whereas activity linked to the stimulus will
• Advantages of investigating brain activity in humans rather than generalising from animal lesion/single electrode recording studies

  • For validity and ethical reasons
• ERPs

  Cheaper than EEGs, so can be more widely used in research
• ERPs


  • Bring more specificity to the measurement of neural processes than could ever be achieved by raw EEG data
• ERPs


  • Have excellent temporal resolution, especially when compared to fMRI, leading to their widespread use in the measurement of cognitive functions and deficits
• ERPs


  • Can measure the processing of stimuli even in the absence of a behavioural response, making it possible to monitor the processing of a particular stimulus without requiring the person to respond to them
• Eval ERPS

  Like EEGs, ERPs have poor spatial resolution

  There is a lack of standardisation in ERP methodology between different research studies, which makes it difficult to confirm findings.

  In order to establish pure data in ERP studies, background noise and extraneous material must be completely eliminated, which may not be easy to achieve.

  Like EEGs, ERPs can only detect the activity in superficial regions of the brain.  Important electrical activities occurring deep in the brain are not recorded, meaning that the generation of ERPs tends to be restricted to the neocortex.
• Post-Mortem Examinations

  •This is 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 are likely to be those who have a rare disorder and have experienced unusual deficits in mental processes or behaviour during their lifetime.•Areas of damage within the brain are examined after death to try to correlate structural abnormalities/damage to behaviour. This may also involve comparison with a neurotypical brain in order to ascertain the extent of the difference.
• Post-mortem studies

  • Allow for a more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with the sole use of non-invasive scanning techniques e.g. fMRI and EEG
  • Enable researchers to examine deeper regions of the brain such as the hypothalamus and hippocampus
• Post-mortem evidence has contributed massively to our understanding of key processes in the brain
• Structural abnormalities of the brain

  Discovered through post-mortem examinations and associated with schizophrenia
• Changes in neurotransmitter systems

  Discovered through post-mortem examinations and associated with schizophrenia