Intracranial high-γ connectivity distinguishes wakefulness from sleep. Mikulan E, Hesse E, Sedeño L, Bekinschtein T, Sigman M, García MDC, Silva W, Ciraolo C, García AM, Ibáñez A. 2018

Intracranial high-γ connectivity distinguishes wakefulness from sleep. Mikulan E, Hesse E, Sedeño L, Bekinschtein T, Sigman M, García MDC, Silva W, Ciraolo C, García AM, Ibáñez A. 2018

AUTORESMikulan E, Hesse E, Sedeño L, Bekinschtein T, Sigman M, García MDC, Silva W, Ciraolo C, García AM, Ibáñez A.
AÑO2018
JOURNALNeuroimage
VOLUMEN1 April, 2018
ABSTRACTNeural synchrony in the γ-band is considered a fundamental process in cortical computation and communication and it has also been proposed as a crucial correlate of consciousness. However, the latter claim remains inconclusive, mainly due to methodological limitations, such as the spectral constraints of scalp-level electroencephalographic recordings or volume-conduction confounds. Here, we circumvented these caveats by comparing γ-band connectivity between two global states of consciousness via intracranial electroencephalography (iEEG), which provides the most reliable measurements of high-frequency activity in the human brain. Non-REM Sleep recordings were compared to passive-wakefulness recordings of the same duration in three subjects with surgically implanted electrodes. Signals were analyzed through the weighted Phase Lag Index connectivity measure and relevant graph theory metrics. We found that connectivity in the high-γ range (90–120 Hz), as well as relevant graph theory properties, were higher during wakefulness than during sleep and discriminated between conditions better than any other canonical frequency band. Our results constitute the first report of iEEG differences between wakefulness and sleep in the high-γ range at both local and distant sites, highlighting the utility of this technique in the search for the neural correlates of global states of consciousness.
RESUMEN

La sincronía neural en la gama alta (90-120 Hz) se ha propuesto como correlato crucial de la conciencia, pero debido a limitaciones metodológicas, esta no es fácil de medir. Comparamos la conectividad entre dos estados globales de conciencia (vigilia y sueño) a través de la registros intracraneales directos, que proporcionan las únicas mediciones de alta frecuencia en el cerebro humano. La conectividad en gama alta en múltiples sectores del cerebro (y su organización en términos de teoría de gráficos), discriminaron la vigilia del sueño mejor que cualquier otra banda y medida. Nuestros resultados constituyen el primer reporte de diferencias entre estados de consciencia  mediante conectividad de gama alta entre regiones locales y distantes.

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