Functional geometry of auditory cortical resting state networks derived from intracranial electrophysiology

Abstract

Critical details remain unresolved about the organization of the human auditory cortical hierarchy and its relationship to higher order brain networks. We investigated this organization using diffusion map embedding (DME) applied to resting state intracranial electroencephalography (iEEG) obtained in neurosurgical patients. DME was applied to functional connectivity measured between regions of interest (ROIs). ROIs exhibited a hierarchical organization, symmetric between the two hemispheres and robust to the choice of iEEG frequency band, connectivity metric, and imaging modality. Tight clusters of canonical auditory and prefrontal ROIs were maximally segregated in embedding space. Clusters consistent with ventral and dorsal auditory processing streams were paralleled by a cluster suggestive of a third stream linking auditory and limbic structures. Portions of anterior temporal cortex were characterized as global hubs. This approach lays the foundation for identifying network changes during active speech and language processing and elucidating mechanisms underlying disorders of auditory processing.

Consciousness is indexed by analogous cortical reorganization during sleep and anesthesia

“…; https://doi.org/10.1101/2022.11.15.516653 doi: bioRxiv preprint electrophysiology studies, as discussed previously (e.g., Banks et al, 2020Banks et al, , 2022. However, we note that results presented in this study were consistent across participants with different seizure foci, clinical histories, and drug regimens.…”

“…Each recording site was assigned to a region of interest (ROI), color-coded according to a functional parcellation scheme illustrated in Supplementary Figure 1a . This scheme was derived from ana analysis of daytime resting state iEEG data from a complementary dataset obtained during daytime wake 43 . To investigate changes in cortical network organization during transitions in arousal and awareness, data were recorded during induction of propofol anesthesia just prior to removal of electrodes ( N = 14 participants; Supplementary Figure 2 ), and during overnight sleep ( N = 15 participants; Supplementary Figure 3 ).…”

“…Functional connectivity was calculated as orthogonalized gamma band power envelope correlations 43,45 , yielding for each one-minute data segment an electrode × electrode connectivity matrix. The first steps of DME analysis are to create a similarity matrix by applying cosine similarity to the functional connectivity matrix, then normalize, threshold, and make symmetric the similarity matrix to yield a diffusion matrix P symm .…”

“…Clustering of functional regions in embedding space. ROIs were categorized into 9 functional regions based on analysis of resting state data from a different cohort of participants (Banks et al, 2022). A small number of sites in ROIs that were not used in the scheme in Banks et al, 2022 were assigned to ROI clusters based on anatomical and functional criteria.…”

“…We focused here on a specific functional connectivity measure (orthogonalized power envelope correlations) and a specific frequency band (gamma). We focused on this band and this measure because our previous work demonstrated its utility for performing DME analysis 43 . However, we also note that the results of that paper were robust to choice of frequency band, and expect that the results presented here would also not depend strongly on that choice.…”