HC12 Multimodel Flashcards
Muli-modal imaging
Combines different imaging techniques to maximize strengths and overcome weaknesses
What are the benifits of multi-modal imaging?
- Improves spatial & temporal resolution
- More comprehensive insights into brain processes
Simultaneous vs. separate recording
Simultaneous: No between-subject variance, no practice effects, but higher discomfort & artifacts
Separate: Reduces interference but introduces variability
Simultaneous recording - advantages
- Mandatory if neural events are state-dependent and vary with different contexts.
- No between-subjects variance.
- No order or practice effects, because you do it at the same time.
- Identical situation.
Simultaneous recording - disadvantages
- Specific instrumentation has to be developed.
- Degraded data quality in terms of signal to noise and increased artifacts.
- Increased subject discomfort and set-up time, because the more methods you have, the more time it takes to set-up.
fMRI and EEG
fMRI has a high spatial resolution including subcortical areas and EEG has a high temporal resolution including cognitive processes. → combining gives both high spatial and temporal resolution.
fMRI and EEG options
o Two parallel (sequential) data sets, analyse them separately and compare them (correlation).
o Use fMRI localizer for EEG source reconstruction: use the fMRI localizer while reconstructing the neural sources of EEG signals. But be aware that EEG has a low spatial temporal resolution.
o Use EEG single-trial amplitudes as parametric modulator in GLM: simultaneous.
fMRI and PET
fMRI has a high spatial resolution and PET looks at the neurotransmitter binding and has an okay spatial resolution. PET has no event related designs, you have to use block-designs, so the comparison might be a little bit difficult, because with fMRI you use event-related designs. You use this to get information about the HRF (fMRI) and metabolism or neurotransmitter binding (PET).
TMS and fMRI
It can tell you something about causality and about the location of activations. TMS can result in long-lasting changes in structure, but is limited to cortical areas while fMRI can also measure subcortical areas.
rTMS and PET
To induce long lasting changes and get information about causality (TMS).
Pharmacological manipulations
You can combine this with any other method, so EEG, fMRI, TMS and PET, under strict ethical guidelines. But be aware: the drugs can change the effect that you’re not interested in, because there is a change in hemodynamics.
Conflict monitoring
Zero is the stimulus onset, so stimulus related. Mainly in the posterior part.
Error processing
To examine this, you look at the error related negativity. It is more negative if you have incorrect trials compared to when you have correct trials. Zero is the stimulus response, so response related. Both ECC and ACC?
Conjunction analyses
Analysis which examines regions that are both involved in the one process and in the other as well.
Example Univariate analysis of fMRI (dyslexia)
With dyslexia, there is a dysfunctional involvement of particular information processing steps in people. There is an exceptionally high or low overall activity in the auditory cortex.
Example decoding MVPA (dyslexia)
Here is a change in the representational content, so there is a difference in representations between people with and without dyslexia. There are sound representations in the auditory cortex.
→ Result: There seems to be no deficit in sound representations, because the representations were quite similar.
Example anatomical/ functional connectivity analysis (dyslexia)
There is a change in access to representations between people with or without dyslexia. Other brain regions have less access to sound representations.
→ Result: there is reduced connectivity between IFGL (Broca) and auditory cortex in people with dyslexia compared to normal readers. So people with dyslexia have a different way to access the representations.
