cognitive methods Flashcards
patient HM
neurosurgery for epileptic seziures
hippocampus - amnesia - brain areas association with memory
donated brain to research
prosopagnosia findings
lesions to the temporal lobe recognise faces
Achromatopsia
grey visuals- lesions - atoprhy to temporal lobes
patient GY
lesion to the left hemisphere - trauma - blind sight
primary visual cortex is not the only area associated with vision
V5 = can respond to visual motion but not static
what is a double dissociation
two brain areas are not associated and have different functions discovered doing two tests
e.g., language
comprehansion and production arent in the same area
TMS - transcranial magnetic stimulation
temporialy disables an area in the brain via stimulation effecting the magnetic field around the brain
how does an EEG work?
dipoles in body formed by pyramidal neurons
when pyramidal neurons recieve action potential from presynaptic neuron the membrane potential changes
organised in a regular way
on scalp
record with eeg
problems with EEG
spatial prescision
is it recording excitatory or inhabatory effects
wheel and Wiesel
bar in vision, moved it around and listened to the action potential of neuron to understand how we see and where
mapped out visual
semir zeki
captured different neural response and what they and their arrangement.
visual cortex has different tunings with specific properties
v1 = blobs
single unit electrophysiology
microelectrodes to record action potential firing to faces but no other stimuli
ERP
loads of trial like 100
to get rid of background oscciliations
selectivity to objects
problems with ERP
so many singlas in the brain can give response to the same pattern across the scall
MEG scan
uses magnetic field rather than electrodes
magnetic field changes are small so requirs powerful detector
cool with liquid helium, expensive
need magnetic shield room
more reliable
how does MRI work?
nucleus of atoms have charged particles
these spin
spinning charges have magnetic properties
when protons in magnetic field they align with it
some parallel some anti parallel
the difference in parallel and anti parallel provides the basis of signal we use to read MRI scan
diffusion tensor imaging
measures the wiring of the brain
focus on cortex
white matter connects brain regions
captures diffusion of water, greater along axon
a signature of brain direction can be measured
PET scan
intravenously insert radiation
positron and electron collide
annihilate each other
photons come from this in both directions
these photons are measured
more photons where these is most activity
when is PET used
useful clinically but too harmful for research
cancer and AD
invasive
how does an fMRI work?
neural activity consumes oxygen
decreased in oxygenated blood
then an increase in more than what was at rest
blood oxygen changes magnetic properties
changes mri signal
what is the change in mri signal due to change in magentic properties called
BOLD signal
what does BOLD stand for
BLOOD OXYGENATED LEVEL DEPENDENT
what is the bold signal
slow
5-10 seconds after stimulus is presented
poor temporal res
how is BOLD signal resolved
resolve using block designs
stimulation stage vs controlled stage
what is unique about the V4
only been found in the human brain, for colour perception
