Miriam Hägele, BCCN Berlin / TU Berlin

The lamina-specificity of multimodal imaging signals in early visual cortex

Multimodal integration of EEG and BOLD-contrast fMRI will benefit from the high temporal resolution of EEG signals together with the high spatial resolution of fMRI responses. The aim of this project therefore was to probe the lamina-specific relation of concurrently measured EEG and fMRI signals during a well-studied paradigm. This task elicited long lasting modulations in different frequency bands, especially the gamma band (45-96 Hz), which originated from early visual cortex. This and the segregation of the BOLD signal by retinotopy, enabled us to investigate the relation of the two modalities in primary visual cortex. Crucially, due to different functional properties of the cortical layers, we were interested in studying this relation across different laminae. The simultaneous recording of the signals furthermore allowed us to probe multimodal integration on a single trial basis.

In order to evaluate the distribution of spectral density across cortical depths, we applied a biophysical modelling approach, dynamic causal modelling (DCM), to a single source in early visual cortex. In particular, we used the fact that DCM models activity at the level of neuronal populations. These estimates of spectral densities were subsequently used in a statistical parametric mapping approach to explain the variability in the laminarly resolved BOLD response. We found that gamma in the supragranular layer is correlated to the BOLD signal in all layers but significantly more to the supragranular layer.

Additional Information

MSc defense as part of the Master of Science in Computational Neuroscience of the BCCN Berlin

Organized by

Klaus-Robert Müller

 

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