How We Investigate The Brain?

How We Investigate The Brain?

1. Functional Magnetic Resonance Imaging (fMRI)

   • What is it?
     • A method used to measure brain activity while a person is performing a task that uses MRI technology (detecting radio waves from changing magnetic fields). This enables researchers to detect which region of the brain are rich in oxygen and thus active.
   • How it works?
     • Produces 3-dimensional images (activation maps) showing which parts of the brain are involved in a particular mental process and this has important implications for our understanding of localisation of functions. It works by detecting the changes in blood oxygenation and flow that occur as a result of neural (brain) 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 (known as the haemogynaic response)
   • Evaluation
     • Limitation: It is expensive compared to other neuroimaging techniqques, and you can only get a clear picture when the patient is perfectly still. It has poor temporal resolution because there is a 5-second time-lag behind the image on the screen and the initial firing of neurol activity. Finally, it only measure blood flow in the brain , it can not home in on the activity of individual neurons and so it can be difficult ot tell exactly what kind of brain activity is being represented on the screen
     • Strength: it doesn't rely on radiation. If administered correctly it is virtually risk-free, non-invasive and straight-forward to use. It also produces images that have very high spatial resolution, depicting detail by the millimetre, and providing a clear picture of how brain activity is localised

2. Electroencephalogram (EEG)

   • What is it?
     • A record of the tiny electrical impulses produced by the brain 's activity. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain.
   • How it works?
     • It is often used by clinicians as a diagnostic tool as unusual arrhythmic patterns of activity may indicate neurological abnormalities such as epilepsy, tumors or disorders of sleep. It measures electrical activity within the brain via electrodes that are fixed to an individual's scalp using skull cap. The scan recording represents the brainwave pattern that are generated from the action of millions of neurons, providing an overall account of brain activity
   • Evaluation
     • Strength: It has been invaluable in the diagnosis of disorders, such as epilepsy. It has contributed much to our understanding of the stages involved in sleep. It has extremely high temporal resolution- can accurately detect brain activity at a resolution of a single millisecond.
     • Limitation: The EGG signal is not useful for pinpointing the exact source of neurol acitivity, and it doesn't allow for researchers to distinguish between activities originating in different but adjacent locations

3. Event- related potentials (ERPs)

   • What is it?
     • The brain's electrophysiological response to a specific sensory, cognitive or motor event can be isolated through statistical analysis of EEG data.
   • How it Works?
     • Using a statistical averaging technique, all extraneous brain activity from the original EGG recording is filtered out leaving only those responses that relate to, say, the presentation of a specific stimulus or performance of a specific task. What remains are even-related potentials: types of brainwave that are triggered by particular events. Research has revealed many different forms of ERP and how, for example, these are linked to cognitive processes such as attention and perception
   • Evaluation
     • Strength: Bring much more specificity to the the measurement of neural processes than EGG. They have excellent temporal resolution, which has lead to their widespread use in the measurements of cognitive functions and deficits.
     • Limitation: Lack of standardisation in ERP methodology between different research studies which makes it difficult to confirm findings. To establish pure data in ERP studies, background noise and extraneous material must be completely eliminated, and this may not always be easy to achieve.

4. Post-mortem examiniations

   • What is it?
     • The brain is analysed after death to determine whether certain observed behaviours during the patient's lifetime can be linked to abnormalities in the brain
   • How it works?
     • 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 as a mean of establishing the likely cause of affliction the person suffered. This may also involve comparison with a neurotypical brain in order to ascertain the extent of the difference.
   • Evaluation
     • Limitation: Observed damage to the brain may not be linked to deficits under review but to some other unrelated trauma or decay (causation). Patients may not be able to provide informed consent, i.e. case study of HM.
     • Strength: Post-mortem studies improve medial knowledge and help generate hypotheses for further study.