title: Human brain oscillatory activity phase-locked to painful electrical stimulations: a multi-channel EEG study.
abstract: The main aims of this study were 1) a fine spatial analysis of electroencephalographic (EEG) oscillations after galvanic painful stimulation (nonpainful stimulation as a reference) and 2) a comparative evaluation of phase- and nonphase-locked component of these EEG oscillations. Preliminary surface Laplacian transformation of EEG data (31 channels) reduced head volume conductor effects. EEG phase values were computed by FFT analysis and the statistical evaluation of these values was performed by Rayleigh test (P < 0.05). About 50% of the EEG single trials presented statistically the same FFT phase value of the evoked EEG oscillations (phase-locked single trials), indicating a preponderant phase-locked compared to nonphase-locked component. The remaining single trials showed random FFT phase values (nonphase-locked single trials), indicating a preponderant nonphase-locked compared to phase-locked component. Compared to nonpainful stimulation, painful stimulation increased phase-locked theta to gamma band responses in the contralateral hemisphere and decreased the phase-locked beta band response in the ipsilateral hemisphere. Furthermore, nonphase-locked alpha band response decreased in the ipsilateral fronto-central area. In conclusion, both decreased and increased EEG oscillatory responses to galvanic painful stimulation would occur in parallel in different cortical regions and in the phase- and nonphase-locked EEG data sets. This enriches the actual debate on the mapping of event-related oscillatory activity of human brain.
authors.affiliation: Dipartimento di Fisiologia Umana e Farmacologia, Università di Roma "La Sapienza," Rome, Italy. claudio.babiloni@uniroma1.it
authors.forename: Claudio
authors.initials: C
authors.lastname: Babiloni
authors.forename: Fabio
authors.initials: F
authors.lastname: Babiloni
authors.forename: Filippo
authors.initials: F
authors.lastname: Carducci
authors.forename: Febo
authors.initials: F
authors.lastname: Cincotti
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Rosciarelli
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.forename: Andrew C N
authors.initials: AC
authors.lastname: Chen
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Rossini
mesh_terms: D000344:Afferent Pathways / Q000502:physiology*; D001683:Biological Clocks / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology*; D004558:Electric Stimulation; D004569:Electroencephalography / Q000379:methods*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D009431:Neural Conduction / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D011930:Reaction Time / Q000502:physiology