PSY2002 S2 W6 fMRI & Cognition Flashcards
(37 cards)
What is cognitive psychology?
The study of human mental processes
What tools are used in cognitive psychology?
tasks that employ specific cognitive processes
What measures does cognitive psychology use?
accuracy, reaction times, eye movements
What is neuroscience?
study of the brain and nervous system
What are tools used in neuroscience?
brain imaging tools (EEG, fMRI, etc)
What measures are used in neuroscience?
EEG signal (ERP), BOLD signal, etc
What is cognitive neuroscience?
The study of the relation between brain structures/activity, and cognitive functions.
The study of cognitive processes using neuroscientific measures and knowledge
What is an example of cognitive processes being studied with neurosceintific measures and knowledge?
Face N170
Studies show a larger N170 response to faces than objects.
Studies examine the properties that affect face processing (inversion, unaffected by familiarity) and how it affects N170.
Researchers concluded that N170 reflect the structural encoding of faces prior to their identification. (Eimer, 2011)
Other researchers use group difference in N170 to conclude about face processing in different groups (Feuerriegel et al., 2015)
Some researchers suggested an alternative explanation of N170: that N170 is merely associated with low-level features in face pictures.
What are fMRI ?
Deoxygenated blood is affected by a magnetic field differently than oxygenated blood.
When neurons are active, they burn energy. This is automatically replenished via oxygen carried by hemoglobin in the blood stream
Active parts of the brain contain more oxygen-rich blood
By measuring the BOLD (Blood Oxygen Level Dependent) response in the MRI scanner, we can work out which parts of the brain were active recently.
What are MRI?
1- Patient Platform: where the patient lies in the exact centre of the magnetic field. The water & at in our bodies means that we are full of hydrogen atoms and MRI targets them.
2- Magnet are used
3- Radio frequency coil: direct a radio wave at the area you want to examine and detects the waves bounded back
Atoms that are like constantly spinning magnets, they align when in a scanner’s magnetic field. You send in radio waves to make them face in a new direction. They relax and return to their previou salignment they emit energy.
What are MRI scans?
Static structure of the brain.
Hydrogen atoms in different tissues (such as fat and water) have different relaxation times can be identified separately. The lower the water content of an area the fewer hydrogen atoms there will be emitting signals. the weaker the signal the darker the area appears on the scan.
Results: shades of grey, fat is quite light but bone is dark
How do fMRI works?
Oxygen is delivered to neurons by haemoglobin in capillary red blood cells. More haemoglobin present in areas of the brain when it needs to replenish the oxygen used by active neurons.
What is the BOLD signal?
Blood oxygen level dependent
What are the advantages of fMRI?
Excellent spatial resolution (get structural data within same session)
Non-invasive
Tells us which parts of the brain are used in tasks.
What are disadvantages of fMRI?
Poor temporal resolution
Experience: noisy, have to stay very still, claustrophobic
BOLD isn’t a direct measure of activity and care should be taking interpreting it
Expensive
Can’t have any metal-based equipment for stimulus presentation
How does culture affect face processing?
Adams et al. 2010
Japanese and American PTT shown Chinese and white American faces and they need to say what was the expression in the eyes.
Results:
Japenes: lower accuracy for America stimuli, the Japanese students showed a own race effect, better at understanding the stimuli from their own race same results were shown for american’s with the own race affect
fMRI: Posterior Superior Temporal Sulucus (pSTS) - focus on this one area
How does culture affect face processing? fMRI
Adams et al.
Left STS: same-VS other-culture mental state decoding
Right STS: Same-VS-Other-culture mental state decoding
In all cases boht sides of the brain both cultures there was high pSTS for same culture stimulus compared to other cultures timuli.
What is the Posterior Superior Temporal Sulcus (pSTS)?
Sensitive to lip reading, mouth movement, body movement, eye gaze, hand action:
- Single-cell recordings in monkeys
- Neurophysiological and neuroimaging studies in humans
Sensitive to implied motion and more generally to stimuli that signal the actions of another individual (Allison et al., 2000).
Conclusion: pSTS activity reflects high-level reasoning and action interpretation
What was the conclusion of both behaviour and fMRI findings?
Adams et al. 2010
Behavioural Findings: Both Japanese and white American participants showed own-race effect when decoding mental state from the eyes.
fMRI Findings: Performance pattern was mirrored by culturally tuned neural activity in the bilateral pSTS. Overall, there was a high-level of consistency in neural responses between Japanese and white American participants when decoding mental states from the eyes
What did fMRI tell us about own race bias ?
Adam et al. 2010
Own race bias in the ability to decode mental states can be seen via consistent brain pSTS activity.
pSTS activity = high-level reasoning and action interpretation
Own race bias in mental state decoding is associated with different abilities in reasoning and interpreting stimuli for same versus other race (not, for example, low-level perception)
The fMRI records activity from all of the brain. Why focus only on a single (or a small number of) specific area(s)?
Neuroscience is sensitive to “alpha inflation” due to multiple comparisons. If we compare numerous areas, we’ll eventually find a statistical difference due to type-1 error
The researchers compared activity to a “gender discrimination” task. Why?
Any stimulus results in a lot of activation that is unrelated to the target process.
Gender discrimination is unrelated to people’s intent. By comparing both tasks, we ensure that the difference doesn’t stem from low-level differences.
Every task needs its own baseline (which activity do you want to remove?).
What can cognitive neuroscience study?
Individual Differences
Do autistic individuals and neurotypical individuals process emotional images in the same way?
Kana et al. 2016
Task: which emotion is blurred?
Explicit emotion condition vs Implicit emotion condition
Results: No behavioural differences in accuracy or RT.
Main results:
Both the autistic and neurotypical PTT activated a similar network of brain regions when explicitly asked to identify emotional expressions.
Autistic PTT had reduced activation in the MPFC and pSTS relative to neurotypical PTT for implicit emotion processing but not during explicit emotion processing
