Consciousness and cortical responsiveness: a within-state study during non-rapid eye movement sleep

• DOI: 10.1038/srep30932
• Publication Date: 2016-08-05T10:57:19Z
• Authors: Jaakko O. Nieminen; Olivia Gosseries; Marcello Massimini; Elyana Saad; Andrew D. Sheldon; Melanie Boly; Francesca Siclari; Bradley R. Postle; Giulio Tononi
• Keywords: Cerebral Cortex; Male; 0301 basic medicine; Multidisciplinary; Neuronal Plasticity; Consciousness; Sleep, REM; Electroencephalography; ta3112; Synaptic Transmission; Transcranial Magnetic Stimulation; Article; Dreams; 03 medical and health sciences; Non-REM sleep; Cerebral Cortex/physiology; Consciousness; Dreams/physiology; Electroencephalography; Female; Humans; Male; Neuronal Plasticity; Sleep/physiology; Sleep, REM/physiology; Synaptic Transmission; Transcranial Magnetic Stimulation; Wakefulness/physiology; Humans; Female; Wakefulness; Sleep

Abstract When subjects become unconscious, there is a characteristic change in the way cerebral cortex responds to perturbations, as can be assessed using transcranial magnetic stimulation and electroencephalography (TMS–EEG). For instance, compared wakefulness, during non-rapid eye movement (NREM) sleep TMS elicits larger positive–negative wave, fewer phase-locked oscillations an overall simpler response. However, many physiological variables also when go from wake sleep, anesthesia, or coma. To avoid these confounding factors, we focused on NREM only measured TMS-evoked EEG responses before awakening asking them if they had been conscious (dreaming) not. As shown here, reported no experience upon awakening, evoked negative deflection shorter response dream. Moreover, amplitude of deflection—a hallmark neuronal bistability according intracranial studies—was inversely correlated with length dream report (i.e., total word count). These findings suggest that variations level consciousness within same state are associated changes underlying cortical circuits.