Lecture 24 fMRI Interpretation Flashcards
(13 cards)
What is a major issue with significance testing in fMRI studies?
Significance testing can lead to many false positives due to running thousands of voxel-wise tests, requiring correction methods like Bonferroni.
Why is Bonferroni correction used in fMRI data analysis?
To reduce the risk of false positives when conducting multiple comparisons across thousands of voxels.
What is the problem of reverse inference in fMRI?
It’s when activation in a brain region is assumed to reflect a specific cognitive process, without accounting for that region’s involvement in multiple tasks.
What is Duncan’s theory about prefrontal cortex activation?
That it’s part of a Multiple Demand Network, activated by various high-level cognitive tasks depending on task difficulty.
What alternative theory suggests specialisation in the prefrontal cortex?
That more anterior regions represent abstract information, while posterior regions represent more specific content.
What is the problem of task specificity in fMRI?
If a task involves multiple cognitive processes, it’s hard to isolate which process a brain region reflects.
What does Poldrack suggest is required to learn from fMRI?
High specificity of both the cognitive task and the brain region involved.
Why are null results problematic in fMRI research?
Because statistical tests are not designed to confirm the null hypothesis, making it hard to interpret non-significant results.
What limits the spatial resolution of fMRI?
Each voxel covers a large number of neurons, making it hard to detect small-scale neural differences.
Why might fMRI fail to detect differences in the primary visual cortex?
Because voxels contain many neurons with different orientations, averaging out specific responses.
What limits the temporal resolution of fMRI?
- Because it takes ~1-2 seconds to measure the entire brain once, we cannot see any changes that take place within this time period showing aggregated response over time
- This is often referred to as the “poor temporal resolution” of fMRI
o If we want to measure neural activity changes for fast processes, we need a different method (such as EEG or MEG)
What is the value problem in neuroimaging?
Neuroimaging might not always add meaningful value or explanation, especially without clever experimental design.
What is the best approach to studying cognition using neuroimaging?
Using carefully designed paradigms and combining multiple methods (EEG, MEG, fMRI) to match spatial and temporal needs.
