Tonic resting-state hubness supports high-frequency activity defined verbal-memory encoding network in epilepsy [article]

Ganne Chaitanya, Walter Hinds, James Kragel, Xiaosong He, Noah Sideman, Youssef Ezzyat, Michael R Sperling, Ashwini Sharan, Joseph I Tracy
2019 bioRxiv   pre-print
High-frequency gamma activity (HFA: 45 to 95Hz) on invasive electroencephalogram coupled with verbal-memory encoding has laid the foundation for numerous studies testing the integrity of memory in diseased populations. Yet, the functional connectivity characteristics of networks subserving these HFA memory linkages remains uncertain. By integrating this electrophysiological biomarker of memory encoding from IEEG with resting-state BOLD fluctuations, we estimated the segregation and hubness of
more » ... A memory regions in drug-resistant epilepsy patients and matched healthy controls. HFA memory regions express distinctly different hubness compared to neighboring regions in health and in epilepsy, and this hubness was more valuable than segregation in predicting verbal memory encoding. The HFA memory network comprised regions from both the cognitive control and sensorimotor processing networks, validating that effective verbal-memory encoding requires multiple functions, and is not dominated by a central cognitive core. Our results demonstrate a tonic intrinsic set of functional connectivity, which provides the necessary conditions for effective, phasic, task-dependent memory encoding.
doi:10.1101/660696 fatcat:f23w3wqbs5dzdcaclhlsxispm4