Poster A96, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
Novel characterization of an architecturally distinct sleep stage and its implications for recovery from the minimally conscious state
Jackie L. Gottshall1,2, Zoe M. Adams1, Peter B. Forgacs1,3,5, Tanya J. Nauvel1,4, Nicholas D. Schiff1,3,5; 1Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, NY, 2Neuroscience Program, Weill Cornell Graduate School of Medical Sciences, NY, 3Department of Neurology, Weill Cornell Medicine, NY, 4Computational Biology and Medicine Program, Weill Cornell Graduate School of Medical Sciences, NY, 5The Rockefeller University, NY
Survival rates from severe brain injuries have increased in recent decades, producing a growing population of patients who avoid fatality yet remain in a chronic condition of ambiguous awareness, termed the minimally conscious state (MCS). Recently, presence of sleep architecture has been correlated with favorable prognosis in MCS, warranting further study of dynamic sleep processes as potential indicators of cognitive recovery. Here we define criteria for a novel sleep stage present in some MCS patients: >70% of the epoch consists of high voltage, low frequency activity (<2Hz) of which ≥50% displays an overriding mid-frequency (8-14Hz) component. Overnight video-EEG of four patients were scored using these criteria and analyzed for spectral content. In all patients, this novel stage occurred predominantly at the juxtaposition of stage 2 and slow wave sleep (SWS) and displayed a unique spectral profile. We posit that unstable transitioning from thalamus-driven stage 2 into deeper, cortically-driven sleep rhythms underlies this novel stage. Notably, in one patient this stage disappeared with concurrent improvements in subjective alertness following initiation of central thalamic deep brain stimulation (Adams et al., 2016). Based on our findings, we propose the presence of a distinct sleep stage during the MCS recovery process indicative of incomplete daytime activation and engagement of neocortical structures that then fail to drive the switch into cortically-driven SWS. This model predicts that: 1) if present, this stage is indicative of preliminary recovery of cortical activation linked to increased daytime arousal and behavioral engagement, and 2) should consistently yield to normal SWS.
Topic Area: METHODS: Electrophysiology