fMRI and cognition Flashcards
how do MRIs work
hydrogen atoms align in scanner’s magnetic field
radio waves make atoms face a new direction
as they return to previous alignment they emit energy (resonance) - used to form an image
H+ atoms have different relaxation times in different tissues
low water content = fewer H+ = weak signal = dark area = bones
more H+ = stronger signal = light area = fat
MRI uses
static brain structure and tissue imaging
fMRI uses
shows function
same technique as MRI but measures blood flow using iron in haemoglobin in the blood
how do fMRIs work
measures blood flow to determine active areas
oxygenated Hb = diamagnetic = weak magnetic field
deoxygenated Hb = paramagnetic = strong magnetic field
BOLD response (blood oxygen level dependent) recorded by fMRI
advantages of fMRI
good spatial resolution
ok temporal resolution
non-invasive
shows which brain areas are used in tasks
disadvantages of fMRI
BOLD doesn’t measure activity directly - interpretating it as such is bad
loud, have to stay still, claustrophobic
expensive
no metal based equipment for stimulus presentation
cross-cultural eyes emotion test in fMRI (Adams et al., 2010)
observed whether same brain areas are activated when observing images of same and other races
better performance with same race images
greater activity in STS (superior temporal sulcus - bilateral) in same race condition
pSTS was used by both races for mental state reasoning and eye gaze
different areas used when reading eyes of other cultural group
processing of emotion in images when prompted vs not and autism (Kana et al., 2016)
3 types of trial:
asked what emotion is shown in image (explicit)
asked to identify an object in an image which has high emotional content (implicit)
neutral stimulus (no emotional content)
compared fMRI of neutral with other 2 conditions to see difference in activity (explained by emotion processing)
results:
explicit = ASD and control showed very similar brain activity when processing emotions (MPFC and pSTS activation)
implicit = control used same brain areas as explicit, ASD process the emotion less
conclusions:
ASD need prompting to process emotions
reduced activity may indicated reduced reflective thought and spontaneous emotion processing - issues recognising subtle emotion
2nd vs 3rd person cognitive neuroscience stimuli
third = non-interactive stimulus
passive perception
pre-recorder that participant knows is pre-recorded
second = interactive stimulus
gaze contingent avatar
live social partner transmitted real time via video link
pre-recorded stimuli the participant thinks is real
what can be learnt from second person stimuli in research
influence of one person on another
mirror neuron circuits
social behaviour (and those who struggle with this)
different task activation - different regions and levels of activity
hyperscanning
cognitive neuroscience of real-world interactions
dual brain studies - simultaneously recorded brain activity
comparison of activity from sender and receiver of activity
can be simultaneous or sequential (one person is prerecorded)
hyperscanning of emotions in romantic partners (Anders et al., 2011)
female in fMRI asked to express a list of emotions, this is video recorded
male watch video in fMRI and asked to “feel” the emotion with her
results:
shared network effect
very similar brain activity seen
better perception with romantic partners vs other people in random pairings
conclusions:
shows how one persons brain activity can influence another’s - transfer of info
shared space of affect
brain as predictor approach
neural mechanisms predict real world outcomes
previous studies observe activity as a result of psychological process, not the inverse
can be used for interventions
iterative process
