Date Elite
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Visual perception
frequency dependent, hierachical manner, feature dependent
Kwon, Watanabe, Fischer, Bartels. Neuroimage. 2017
Kwon, Bartels. Submitted & Kwon, Bartels. in prep
fMRI connectivity
Visual attention changes fMRI connectivity
How does visual attention change the brain activity or the connectivity? Prior studies used low-frequency fMRI (<0.1Hz) to examine the connectivity pattern during rest, but task-based studies used relatively fast frequency fMRI oscillation (>0.1Hz).
In our study, we used a long trial interval to observe the low frequency (>0.05Hz) of the hemodynamic oscillations that has been heavily studied with electrophysiological link.
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We found that attention changes connectivity in frequency dependent manner (Kwon. Neuroimage 2017), in hierarchical manner (Kwon. submittted) and feature-based manner (Kwon. in prep)
fMRI vs EEG
Whittingstall, Bartels, Singh, Kwon, Logothetis. MRI. 2010
Are we measuring neuronal activity? fMRI studies are commonly used to study human brain non-invasively. Yet many people regard the fMRI activity as output signal of the neuron. However, but fMRI signal correlates more to the input to the neuron by monkey studies. What about the relationship between fMRI and EEG signal in the human brain? We found that in human brain, the relationship (impulse response function) between two signals are similar to the monkey brain
Relationship between fMRI and EEG source during movie viewing​
Auditory perception
Ko, Kwon, Lee, Im, Kim, Jung. J Clin Neuro. 2012
EEG spectral
Auditory discrimination task is based on theta power change
How do we discriminate sound? We presented control and oddball sounds to healthy people and record their EEG activity. The power and phase of the theta band (3-12Hz) was changed in the frontal cortex by using time-frequency analysis of single trial event-related potentials
fMRI connectivity
Word attention strengthens
the connecvity between
Broca’s and Wernicke’s
area
How is the brain connected during word listening and how it changes by attention? We tested this when people listen to 4 similar words (recorded by myself!) and they had to discriminate those words. We found that attention strengthens connectivity across Broca's area and opposite to Wernicke's area (right side)
Fear perception
fMRI MVPA
Neural correlate of defensive switching
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Where in the brain responds to fear? More specifically, when you have to switch from the attack and escape from it or vice versa, which brain region will respond to it? This has been heavily studied in rodent, but not much in primate (including us). We are interested in studying this in human by using multivariate pattern analysis