Ways of studying the brain

fmRI, post-mortems, EEG and EPS

Post mortem AO1

• Used to examine brain to look for abnormalities not found control groups, may study person who showed interesting beh when alive which could indicate brain damage

• Happens on deceased brain

• E.g. Broca studied Tan - speech problems when alive - lesion in frontal lobe ‘brocas area’ on post-mortem

• Most common technique is histology - brain removed from skull, cut into thin slices + studied under microscope

• Stained purple so easier to see cell fibres under microscope

Post mortem AO3 useful tool

• P: allows researchers to study brains structure at deeper microscopic level inc neuron’s + synapses which cannot be observed with non-invasive techniques eg fMRI

• E: examine deeper brain regions eg hypothalamus - structural abnormalities eg enlarged ventricles - linked to schizophrenia - advanced biological basis of mental disorder

• L: crucial insights which improve medical knowledge + generate hypotheses for further experiments - contributing to better diagnosis + treatment

• H: depends on brain donations - could wait many years for suitable samples - slow scientific progress - ethical issues around consent for cognitively impaired

Post mortem AO3 confounding influences

• P: different influences could affect brain structure, hard to establish cause + effect

• E: many ind had LT treatment - affect brain structure/chemistry - difficult to determine whether abnormalities in brain due to disorder or effects of treatment - complicates interpretations

• L: difficult to accurately draw conclusions from studying, limits usefulness

• F: ind may die under very different circumstances, diff extent of disease, length of time between death + examination, age of death — difficult to compare abnormalities with controls to find difference - also generalisability

Further unelaborated post mortem evaluation points

• No opportunity to follow up on findings to see ongoing cognitive/behavioural changes - lack experimental control

• Difficult to assess whether brain abnormalities caused symptoms or were caused by them eg neurodegeneration

• Better when converged with other methods: behavioural studies, fMRI, essential for confirming biological theories

• Not helpful to patient but might bring peace to family

FMRI AO1

• Measures changes in brain activity while Ind performs task eg cognitive (eyesight)

• Neurons most active require increased energy - need oxygen + glucose in blood - when brain region is active = blood flow increases

• Changes in blood flow measured using radio waves and magnetic fields

• Areas with high levels oxygenated blood shown red - lower levels cooler colours

• Two brain scans needed - 1 before task as baseline to measure activity associated with task

fMRI AO3 non-invasive

• P: non-invasive - safer + more accessible - no physical intrusion or exposure to harmful substances

• E: better than PET scans which require injection of radioactive tracers that carry potential health risks - it can be administered safely + repeatedly without harmful side effects

• L: strength as encourages ease + access of use, which allows scientific research to become less limited, allows progression over time to be tracked - repeated use (unlike PM)

• H: focuses solely on localised brain activity - overlooks networked nature of brain + integration between brain areas - leads to incomplete understanding of brain processes

FMRI AO3 objective

• P: highly objective + reliable method - scientific data

• E: Shegrill used fMRI to identify brain areas active in schizophrenic patients auditory hallucinations, very high spatial resolution

• L: more scientific + objective - enhances understanding of underlying brain processes linked to mental disorders - legitimise - informs biological treatments

• H: research in field is limited by economic implications: £230 per scan

Further AO3 fMRI points

• Highly standardised - increases replicability adding credibility to findings

• Allows researchers to observe mental processes that are difficult to verbalise

• Low temporal resolution - does not measure neural firing + lags

• Useful to link brain activity to task performance

EEG AO1

• Measures electrical activity in the brain

• Electrodes placed on the scalp - detect small electrical charges from activity of brain cells

• Used to diagnose Alzheimer’s, epilepsy and sleep disorders

• Measures amplitude & frequency of brain waves - synchronisation (regular pattern) or desynchronisation (irregular)

• Epilepsy shows spikes of electrical activity

• Normal activities at same time

EEG AO3 non-invasive

• P; non-invasive

• E: can perform activity at same time, comfortable, silent - can be used for infants, elderly, neurologically impaired

• L: more inclusive + ethically appropriate - allows it to be used by everyone even those limited

• H: electrical activity picked up by neighbouring electrodes - not useful to pinpoint exact source of neural activity - cannot distinguish between different, adjacent areas - less accurate + reliable than fMRI

EEG AO3 - temporal resolution

• P: high temporal resolution - real time recording of brain activity unlike FMRI

• E: track exact timing of neural events - shows how quickly the brain responds to stimuli or does cognitive processes

• L: accurate measurement of brain activity in real time - which helps to understanding fast changing responses

• F: used to diagnose + monitor epilepsy - real world value

ERPS AO1

• Electrodes placed on scalop

• Stimulus presented to p + researcher looks for brain activity related to

• Hundreds of readings taken + average response graphed - makes specific response to the stimulus stand out

ERPS AO3 high temporal resolution

• Tracks brain activity to millisecond to measure neural processes as they happen

• E: led to enhanced understanding of cognitive function eg attention, perception and memory

• L: useful in allowing investigations of deficits in these areas eg memory impairements - helps to diagnose

• H: only detect neural activity in brain regions close to scalp - not deeper brain structures - restricts usefulness detecting areas eg hypothalamus

ERPS AO3 cost effective

• EEG and ERP cheaper than other techniques eg fMRI

• Can be used by smaller universities + hospitals - democratising neuroscience researcher to more diverse participant samples - increases generalisability and validity

• L: greater volume of research to be conducted - more studies carried out

• H: not always standardised - different experimental designs , difficult to replicate

• (Time consuming averaging- hundreds of different graphs )