Abstract

Lyubov B. Oknina*, Anna O. Kantserova, Eugeny L. Masherov, Vitaly V. Podlepich, Oleg S. Zaitsev and David I. Pitskhelauri

ABSTRACT

The study aimed to calculate functional connectivity between the cortex and midbrain area (periaqueductal grey, PAG). For this, in 5 patients at the final stage of surgery after removal of the pineal region tumor, the external ventricular drainage with recording devices located at the tip was inserted into the aqueduct. Thus, by draining the cerebrospinal fluid from the ventricular system for therapeutic purposes we could register the local potentials of the periaqueductal region during anesthetic sleep, waking from it and wakefulness. ERPs were recorded simultaneously from deep electrodes located close to intact PAG area and scalp electrodes using auditory two-tone oddball paradigm. The selection of peaks was made in N100, N200 and P300 time windows. Functional connectivity was calculated in time windows including 65 ms before and after peak latency on deep electrode and used in the Granger causality test (value of model order n=10). The peaks recorded on deep electrodes were considered under the same names (N100, N200 and P300) for convenience of description and comparison with those recorded on scalp sites. In clear consciousness ERP was clearly detected on scalp electrodes, as well as peaks on deep electrodes. The changes of direction of functional connectivity were detected during consciousness recovery: the direct connectivity from the frontal area to brainstem was revealed in post-anesthesia disorders of consciousness and obnubilation with the connectivity value greater in post-anesthesia disorders of consciousness, and the direct connectivity from the brainstem to left cortex area was detected in clear consciousness.