Physiological Methods Flashcards
why do we not always add physiological measures
- often takes a lot more time
* techniques themselves are quite complicated in terms of machinery
why do we use physiological methods
- depends on the research question
* can be more sensitive than behavioural data
what does galvanic skip response measure
increases in conductance between two electrodes
- a v low electronic voltage is applied
- often measured in palms and/or fingers
why are we interested in galvanic skin response
- autonomic nervous system
- stress,arousal,emotion,increase activity of sweat glands
heart rate
- increased heart rate is linked to increase in stress arousal emotion ect
- many different ways to measure heart rate
measuring eye movement -autonomic nervous system
pupil constriction/dilation
eye tracking
*using camera and specific software - exact location of a gaze can be determined
what can we use eye tracking for
to study visual information processing and attentional processes
how are eye movements measured
p’s are shown images while their eye movement is recorded
what are the measurements of eye movements
fixation
saccades
what are saccades
rapid eye movement between fixations
what does MRI stand for
Magnetic Resonance Imaging
how does an MRI work
measures the change in magnetic field within a voxel
whats a voxel
a cube which is the smallest measurement point
what are MRI pictures
slices of the brain usually in one of three directions
-3D modelling allows for easy navigation
what does DTI stand for
diffusion tensor imaging
what is DTI
an MRI technique
how does DTI work
if unobstructed water molecules diffuse randomly in any direction
- BUT the axons are bubbled together and have myelin sheilds
what do myelin sheilds do
block the molecules, forcing pattern
what can voxels be checked for
- rate of diffusion
- preferred direction of diffusion
what do elongated ellipsoids indicate
the presence and direction of homogeneous fibre tracts within a voxel
what are DTI’s especially useful for
identifying network connections (or white matter connectivity)
how can DTI’s be used in a clinical setting
to detect tumors in relation to the white matter tracts
problems with DTI
technique is not perfect and has difficulties with ‘crossing fibers’
what does fMRI stand for
functional magnetic resonance imaging
how do fMRI’s worok
it derives brain activity from blood oxygen levels
fMRI and neuronal activity
takes advantage of fact that neural activity is followed by blood flow in a highly predictable manner
whats fMRI an indirect measure of
neuronal activity because it relies on metabolic demands of the brain
what does BOLD stand for - fMRI
blood oxygenation level dependent
why do fMRI’s have poor temporal resolution
BOLD response takes several seconds
step one of fMRO
when a brain region is active it uses energy
step 2 of fMRI - oxygenated blood
to replenish this energy a large volume of oxygenated blood is supplied to this brain region
step 3 of fMRI - magnetic feild
oxygenated blood doesnt influence the magnetic field, so it doesnt influence the MR signal
step 4 of fMRI - deoxygenated blood
deoxygenated blood does influence the magnetic field, so the MR signal is reduced
what does an EEG measure
electric activity originating from within the brain
how do EEGs work
EEF activity reveals the summation of synchronous activity of thousands of neurons
whats an EEG measured through
an array of scalp electrodes
how are pyramidal neurons of the cortex arranged
spatially aligned and perpendicular to the cortical surface
what does the EEG signal reflect
mainly post-synaptic potentials rather than action potentials
what are EEG signals measured in
microVolts
what do ERP’s do
link the continuous EEG to a specific event and see how the brain signal changes during/after the event
- means we can like specific stimuli to a brain response
what does ERP stand for
event related potential
advantages of EEG
- easy to use
- easy to apply
- powerful in determining when something happens in the brain
- cheap compared to fMRI
disadvantages of EEG
- weak in determining where something happend in brain
- time consuming
- requires training and understanding
what do fMRI’s and EEG’s show
correlations
what does TMS stand for
transcranial magnetic stimulation
how does TMS work
we can disrupt ongoing brain activity in a specific region
what does TMS allow
comparison with how people respond to stimuli with and without specific brain area disrupted
what can TMS help demonstate
a causal link between the target brain area and our main experimental condition
how is TMS conducted
using coils that generate a magnetic pulse
why is the coil in TMS used
to target a specific brain area generating a magnetic pulse
advantages of TMS - reactions
good for speech, reaction time and affects accuracy on behavioural tasks
advantages of TMS - performing taks
tells us whether certain areas of the brain are involved in performance in a certain task
advantages of TMS - evidence
can provide evidence for causal relationship between brain and behaviour and that a certain brain area is essential for a certain behaviour or action to take place
disadvantages of TMS - feeling
can be uncomfortable
disadvantages of TMS - reach
cant reach all the brain max depth - half the brain out of reach
disadvantages of TMS - individual differences
not suitable for everyone - especially those with some neurological issues
