title: Spectral parameters modulation and source localization of blink-related alpha and low-beta oscillations differentiate minimally conscious state from vegetative state/unresponsive wakefulness syndrome.
abstract: Recently, the cortical source of blink-related delta oscillations (delta BROs) in resting healthy subjects has been localized in the posterior cingulate cortex/precuneus (PCC/PCu), one of the main core-hubs of the default-mode network. This has been interpreted as the electrophysiological signature of the automatic monitoring of the surrounding environment while subjects are immersed in self-reflecting mental activities. Although delta BROs were directly correlated to the degree of consciousness impairment in patients with disorders of consciousness, they failed to differentiate vegetative state/unresponsive wakefulness syndrome (VS/UWS) from minimally conscious state (MCS). In the present study, we have extended the analysis of BROs to frequency bands other than delta in the attempt to find a biological marker that could support the differential diagnosis between VS/UWS and MCS. Four patients with VS/UWS, 5 patients with MCS, and 12 healthy matched controls (CTRL) underwent standard 19-channels EEG recordings during resting conditions. Three-second-lasting EEG epochs centred on each blink instance were submitted to time-frequency analyses in order to extract the normalized Blink-Related Synchronization/Desynchronization (nBRS/BRD) of three bands of interest (low-alpha, high-alpha and low-beta) in the time-window of 50-550 ms after the blink-peak and to estimate the corresponding cortical sources of electrical activity. VS/UWS nBRS/BRD levels of all three bands were lower than those related to both CTRL and MCS, thus enabling the differential diagnosis between MCS and VS/UWS. Furthermore, MCS showed an intermediate signal intensity on PCC/PCu between CTRL and VS/UWS and a higher signal intensity on the left temporo-parieto-occipital junction and inferior occipito-temporal regions when compared to VS/UWS. This peculiar pattern of activation leads us to hypothesize that resting MCS patients have a bottom-up driven activation of the task positive network and thus are tendentially prone to respond to environmental stimuli, even though in an almost unintentional way.
authors.affiliation: Department of Translational Research on New Technologies in Medicine and Surgery, School of Physical Medicine and Rehabilitation, University of Pisa, Pisa, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Bonfiglio
authors.affiliation: TeCIP Institute, PERCRO Laboratory, Scuola Superiore Sant'Anna, Pisa, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Piarulli
authors.affiliation: Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genova, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Olcese
authors.affiliation: Department of Medical and Surgical Sciences and Neuroscience, University of Siena, Siena, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Andre
authors.affiliation: Department of Translational Research on New Technologies in Medicine and Surgery, School of Physical Medicine and Rehabilitation, University of Pisa, Pisa, Italy.
authors.forename: Pieranna
authors.initials: P
authors.lastname: Arrighi
authors.affiliation: TeCIP Institute, PERCRO Laboratory, Scuola Superiore Sant'Anna, Pisa, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Frisoli
authors.affiliation: Department of Translational Research on New Technologies in Medicine and Surgery, School of Physical Medicine and Rehabilitation, University of Pisa, Pisa, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Rossi
authors.affiliation: TeCIP Institute, PERCRO Laboratory, Scuola Superiore Sant'Anna, Pisa, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Bergamasco
authors.affiliation: Department of Translational Research on New Technologies in Medicine and Surgery, School of Physical Medicine and Rehabilitation, University of Pisa, Pisa, Italy.
authors.forename: Maria Chiara
authors.initials: MC
authors.lastname: Carboncini
mesh_terms: D000328:Adult; D000368:Aged; D000513:Alpha Rhythm; D000704:Analysis of Variance; D001611:Beta Rhythm; D001767:Blinking; D001931:Brain Mapping; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D004569:Electroencephalography; D005260:Female; D006179:Gyrus Cinguli / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D013577:Syndrome; D055815:Young Adult