"Gamma synchrony" in first-episode schizophrenia: a disorder of temporal connectivity?
OBJECTIVE
There has been a convergence of models describing schizophrenia as a disconnection syndrome, with a focus on the temporal connectivity of neural activity. Synchronous gamma-band (40-Hz) activity has been implicated as a candidate mechanism for the binding of distributed neural activity. To the authors' knowledge, this is the first study to investigate "gamma synchrony" in first-episode schizophrenia.


METHODS
Forty medicated first-episode schizophrenia patients and 40 age- and sex-matched healthy comparison subjects participated in a conventional auditory oddball paradigm. Gamma synchrony, time-locked to target stimuli, was extracted from an ongoing EEG. The magnitude and latency of both early (gamma 1: -150 msec to 150 msec poststimulus) and late (gamma 2: 200 to 550 msec poststimulus) synchrony were analyzed with multiple analysis of variance.


RESULTS
First-episode schizophrenia patients showed a decreased magnitude and delayed latency for global gamma 1 synchrony in relation to healthy comparison subjects. By contrast, there were no group differences in gamma 2 synchrony.


CONCLUSIONS
These findings suggest that first-episode schizophrenia patients have a global decrease and delay of temporal connectivity of neural activity in early sensory response to task-relevant stimuli. This is consistent with cognitive evidence of perceptual integration deficits in this disorder and raises the possibility that a breakdown in the early synchrony of distributed neural networks is a marker for the onset of schizophrenia.
Symond
Matthew P
MP
The Brain Dynamics Centre, Westmead Hospital, Westmead, N.S.W., 2145 Australia.
Symond
Matthew B
MB
Harris
Anthony W F
AW
Gordon
Evian
E
Williams
Leanne M
LM
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000494:pharmacology / Q000627:therapeutic use; D001307:Auditory Perception / Q000502:physiology; D002531:Cerebellum / Q000503:physiopathology; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology*; D003344:Cortical Synchronization / Q000187:drug effects / Q000706:statistics & numerical data*; D003627:Data Interpretation, Statistical; D005260:Female; D005625:Frontal Lobe / Q000187:drug effects / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008959:Models, Neurological; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D013788:Thalamus / Q000503:physiopathology; D013997:Time Factors
D014150:Antipsychotic Agents