Biopsychology- brain scanning techniques Flashcards
What is fMRI?
Functional magnetic resonance imaging
What does fMRI measure?
oxygenated haemoglobin blood flow in the brain i.e. brain activity
Why is oxygenated blood measured?
has a different resonance than deoxygenated blood
How does fMRI work?
-The blood flow reacts to the scanner’s magnets
-Deoxygenated blood is present in less active/non-active regions of the brain
-The blood flow equates to activity in the brain which in turn indicates which specific structures are working hard at that point in time
What happens the scan?
-A computer transforms the information into a brightly coloured 3D image which is mapped using voxels (each voxel = thousands of neurons)
-Active areas of the brain can then be compared with areas that are lower in activity which is indicated on the fMRI scan image via the degree of bright colour
What usually happens during an fMRI scan?
-Person performs a task
-Neurons in the brain need energy to perform the task
-Energy requires glucose and oxygen
What is the temporal resolution of fMRI?
-Images show activity 1-4 seconds after it occurs
What is the spatial resolution of fMRI?
-Images are accurate within 1-2 mm
What does EEG stand for?
Electroencephalogram
What does EEG involve?
-Placing of electrodes on the scalp which record brain activity
-Usually between 22-34 electrodes are used but there can be any number from 2-100 depending on the age and size of the participant and what the aim of the research is
-The electrodes are fitted to a cap that is placed on the participant’s scalp along with a conductive gel
-The electrodes measure the activity of the cells directly below them
-The more electrodes there are, the more detailed information and a comprehensive picture of the brain can be derived
-Graphed over a period of time indicating the level of activity
What can EEGs be used for?
Investigating sleep disorders, seizures, memory problems
Brain activity is shown via brain waves, the 1._____ shows the brain intensity and the 2._____ shows the speed of activation
1.amplitude
2.frequency
What do EEGs measure?
Electrical activity through electrodes attached to the scalp
What are the 4 types of EEG patterns (waves)?
-Alpha
-Beta
-Theta
-Delta
Which waves are associated with lighter sleep?
Alpha
Which waves are associated with deeper sleep?
Theta/delta
What is the temporal resolution of EEG/ERP?
Every millisecond
What is the spatial resolution of EEG/ERP?
Only detect activity in superficial, general areas of the brain/ cant detect activity in the hypothalamus/ amygdala
What are ERPs?
Event-related potentials
What is a similarity between ERPs and EEGs?
use the same apparatus and technique
Define event related potentials
tiny voltages generated in brain structures in response to specific events or stimuli
How are ERPs stimulated?
sensory, cognitive or motor events
Define latency
The time or interval between the presentation of the stimulus and the response is referred as latency
What do post-mortem examinations involve?
examining the brain after death to determine the cause of behaviour(s) or dysfunction experienced when the patient was alive
Are the findings of PME typically correlational?
Yes
Give an example of where PM has been used?
Broca and Wernicke’s area
Why are PME useful?
Allow for a more detailed examination of anatomical and neurochemical aspects
Give an evaluation point for PME
-Issues surrounding consent
- The person is deceased so cannot give informed consent
-If they did give consent for this to be done they may not have been fully competent
-Ethical concerns
-However PME allow for a more detailed explanation of anatomical and neurochemical aspects
Give an evaluation point for EEG in comparison to FMRI (Temporal resolution)
-EEG has good temporal resolution
-Temporal resolution refers to the accuracy of the scanner in relation to time/ how quickly the scanner can detect changes changes in brain activity
-EEG scanners take readings every millisecond meaning it can take readings in real time opposed to looking at passive brain
-However FMRI scans have temporal resolution of 1-4 seconds which is worse than other techniques
-This suggest that EEG can provide a high degree of accuracy when examining the onset of brain activity, allowing psychologists to make accurate conclusions in relation to the timing of neural activity in comparison to fMRI
Give an evaluation point for FMRI in comparison to EEG (spatial resolution)
-One strength of FMRI in comparison to EEg is that it has good spatial resolution
-spatial resolution is the smallest feature/measurement that a scanner can detect, greater spatial resolution allows psychologists to discriminate between different regions of the brain with greater accuracy
-EEG om the can only detect the activity in the superficial regions of the brain
-Therefore psychologists can determine the activity of different brain regions with greater accuracy when using FMRI, in comparison to EEGs Which makes fMRI and ideal choice when trying to pinpoint specific brain regions
Give a strength of fMRIs and EEGs (non invasive)
-One strength of fMRIs and EEGs are both non invasive techniques
-For example both brain scanning techniques used imaging scanning techniques such as EEG, ERP and fMRI scans do not involve inserting instruments into the brain or using radiation unlike post mortem exams or Xrays
-This is a strength as it means the procedure is more likely to be risk free
