title: Time-frequency analysis of short-lasting modulation of EEG induced by TMS during wake, sleep deprivation and sleep.
abstract: The occurrence of dynamic changes in spontaneous electroencephalogram (EEG) rhythms in the awake state or sleep is highly variable. These rhythms can be externally modulated during transcranial magnetic stimulation (TMS) with a perturbation method to trigger oscillatory brain activity. EEG-TMS co-registration was performed during standard wake, during wake after sleep deprivation and in sleep in six healthy subjects. Dynamic changes in the regional neural oscillatory activity of the cortical areas were characterized using time-frequency analysis based on the wavelet method, and the modulation of induced oscillations were related to different vigilance states. A reciprocal synchronizing/desynchronizing effect on slow and fast oscillatory activity was observed in response to focal TMS after sleep deprivation and sleep. We observed a sleep-related slight desynchronization of alpha mainly over the frontal areas, and a widespread increase in theta synchronization. These findings could be interpreted as proof of the interference external brain stimulation can exert on the cortex, and how this could be modulated by the vigilance state. Potential clinical applications may include evaluation of hyperexcitable states such as epilepsy or disturbed states of consciousness such as minimal consciousness.
authors.affiliation: Clinical Neurophysiology and Functional Neuroimaging Unit, Section of Neurology, Department of Neurological and Movement Sciences, University of Verona Verona, Italy ; Department of Neurophysiology, Foundation IRCCS San Camillo Hospital Venice, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Manganotti
authors.forename: Emanuela
authors.initials: E
authors.lastname: Formaggio
authors.forename: Alessandra
authors.initials: A
authors.lastname: Del Felice
authors.forename: Silvia F
authors.initials: SF
authors.lastname: Storti
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zamboni
authors.forename: Alessandra
authors.initials: A
authors.lastname: Bertoldo
authors.forename: Antonio
authors.initials: A
authors.lastname: Fiaschi
authors.forename: Gianna M
authors.initials: GM
authors.lastname: Toffolo
keywords: EEG; TMS; cortical excitability; vigilance state; wavelet analysis