Fluctuation of gamma-band phase synchronization within the auditory cortex in schizophrenia.
OBJECTIVE
To study the phase stability of the 40Hz auditory steady-state response (ASSR) in Sz, and in addition, to investigate inter-hemispheric phase synchronization using ipsilateral and contralateral hemisphere gamma band ASSRs.


METHODS
Whole head magnetoencephalography (MEG) was used to detect ASSR from both hemispheres in Sz patients and their control counterparts. Source localization, spatial and temporal filtering were performed to infer gamma band activity from the neural generators of the ASSR. The response gamma band phase stability relative to a reference signal was quantified using the phase synchronization index (PSI).


RESULTS
Results indicated reduced phase synchronization of the ASSR and the stimulus reference signal in Sz patients compared to control subjects, in addition to reduced inter-hemispheric phase synchronization between contralateral and ipsilateral hemispheric responses in Sz patients.


CONCLUSIONS
Greater intra and inter hemispheric fluctuations of ASSR gamma band phase synchronization in Sz add to previous studies suggesting timing deficiencies within neural populations, possibly caused by impairments of neural network parameters.


CONCLUSIONS
This study provides experimental support that may aid in understanding the dynamics of neural phase synchrony caused by modifications of underlying neurotransmitter systems, as reflected in disease states such as schizophrenia.
Maharajh
Keeran
K
Department of Psychiatry, University of Colorado Denver, Anschutz, Medical Campus, MS F-546, 13001 E 17th Pl., Aurora, CO 80045, USA. keeran.maharajh@ucdenver.edu
Teale
Peter
P
Rojas
Donald C
DC
Reite
Martin L
ML
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001303:Auditory Cortex / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D003344:Cortical Synchronization; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000473:pathology*