Techniques for investigating the brain Flashcards
What are the 4 ways to evaluate brain scans
Temporal resolution
Spatial resolution
Invasiveness
Implications
What is temporal resolution
Ability to see the brain respond without delay in real time
What is spatial resolution
Ability to distinguish and investigate different parts of the brain
What is invasiveness
Whether the technique causes harm/discomfort to patient or not
What are implications
Whether the technique has been used to help understand/treat conditions
Describe how functional magnetic resonance imaging works (fMRI)
Measures change in brain activity while task is being performed by measure blood flow change
Certain areas become more active when different tasks are being performed.
Increased activity leads to increased oxygen demand.
Blood flow is increased to meet oxygen demand in the brain
Changes in blood flow are detected by fMRI through colour images so researchers can see which areas are involved in certain activities.
Describe how electroencephalogram works (EEG’S)
Used to measure electrical activity in the brain.
Electrodes placed on scalp detect electrical charge/activity in brain cells
Electrical activity graphed over time produces EEG
Can be used to detect/diagnose disorders affecting brain activity e.g. people with epilepsy show spikes in electrical activity whereas people with degenerative brain diseases e.g. Alzheimer’s show reduced speed in electrical activity
5 EEG patterns – Alpha, Beta, Delta, Theta and Gamma waves
General measure of brain activity
Describe how event related potentials (ERP’S)
Small voltage change in the brain due to specific events e.g. cognitive processing of stimulus e.g. music
Difficult to pick out voltage change related to specific stimulus/event amongst other activities
To counter this, stimulus is presented many times to establish many voltage changes which are then averaged. Other extraneous neural activity most likely won’t occur consistently so it’s easy to choose a specific voltage change to focus on.
Describe how post mortem examinations work
Analysis of the brain after death
Used to analyse the brains of those that had rare disorders/unusual mental or physical behaviour when alive.
Areas of damage within the brain are examined in order to explain abnormal behaviour/disorders
Researchers may compare to a control group(brain belonging to normal function person)
Example – Broca found lesions in an area of Tan’s left frontal lobe(now known as broca’s area) which is responsible for speech production, leading to broca’s aphasia
What are the strengths and weaknesses of EEG’S
Strengths - High temporal resolution
Useful in clinical diagnosis e.g. epilepsy being caused by disrupted brain activity
Weaknesses - Uncomfortable which can lead to false readings
Poor spatial resolution - Can’t analyse deep regions of brain so limited compared to fMRI
What are the strengths and weaknesses of ERP’S
Strengths - High temporal resolution so accurate measurement of electrical activity
Non invasive
Weaknesses - Uncomfortable which can lead to false readings
Poor spatial resolution - Can’t analyse deeper brain regions e.g. hypothalamus so limited in comparison to post mortem
What are the strengths and weaknesses of Post mortem examinations
Strengths - High spatial resolution as you can have detailed analysis
Has lead to understanding of Broca’s(language) and Wernicke’s area(speech production)
Weaknesses - Poor temporal resolution as the brain doesn’t function
Non invasive as the brain doesn’t respond to stimulus so accurate readings can be gained
What are the strengths and weaknesses of fMRI’s
Strengths - High spatial resolution which shows clear image of brain activity
More objective and reliable compared to self report
Weaknesses - Poor temporal resolution as 5 second delay behind image and neuron activity
Expensive compared to other techniques
Person must stay still
