Poster A3, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
EEG Evidence of Covert Command Following and the Impact of State Fluctuations in Patients with Severe Brain Injury
William H. Curley1, Jonathan D. Drover1, Mary M. Conte1, Nicholas D. Schiff1,2,3; 1Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, NY, 2Department of Neurology, Weill Cornell Medicine, NY, 3The Rockefeller University, NY
Patients with disorders of consciousness (DOC) following severe brain injury combine significant motor deficits with fluctuating arousal states, limiting their capacity for behavioral output and often leading to misdiagnosis. Multichannel video-EEG was recorded in 23 severely brain-injured patient subjects (PSs) and 15 healthy controls (HCs) during four distinct motor imagery tasks (tennis, swimming, open/close hand, and visuospatial navigation). We compared power spectral estimates of the EEG during task and rest (1-50 Hz, Two Group Test, p ≤ 0.05) to identify differences in power between conditions, signifying task performance (Curley et al., 2016; Goldfine et al., 2011). Evidence of task performance was found for all tasks in all HCs and for one or more tasks in 16 of 23 PSs. Consistent and concordant spatiotemporal patterns of activation were observed in HCs and the patient responders, despite interpatient variability in extent of injury, etiology, and score on a standard behavioral assessment (CRS-R). However, both transient task performance within the allocated response period and baseline state fluctuations in patient subjects can confound our formal measures and potentially give rise to false negative results. Two methods examined the indeterminate responses to tennis imagery: 1) time-frequency analysis to resolve transient responses, and 2) analysis and grouping of individual trials based on background state reflected in power spectra. We identified previously undetected capacity for command following using these methods. Our findings demonstrate the impact of state fluctuations on DOC patients’ capacities to demonstrate awareness and the need to quantitatively assess state when testing for covert cognition.
Topic Area: ATTENTION: Auditory