An integration of 40 Hz Gamma and phasic arousal: novelty and routinization processing in schizophrenia.
OBJECTIVE
Frontal and lateralized schizophrenia disturbances were examined in terms of arousal-modulated changes in 40 Hz Gamma activity.


METHODS
Forty patients with schizophrenia and 40 age- and gender-matched controls were studied in a conventional auditory ERP oddball paradigm. We investigated sub-averaged Gamma activity based upon a simultaneous measure of electrodemal skin conductance response (phasic arousal) to differentiate novelty (large responses) from routinization (small or no responses). Both early Gamma (Gamma 1) and later induced Gamma (Gamma 2) activities were examined.


RESULTS
Patients with schizophrenia (compared with controls) had significantly reduced Gamma 1 amplitude in the right hemisphere for novelty processing and delayed Gamma 2 latency in the left hemisphere for both novelty and routinization. Overall, reduced Gamma 1 amplitude in patients with schizophrenia was also evident.


CONCLUSIONS
These findings indicate that the normal laterality of Gamma activity is specifically disturbed in schizophrenia in response to novel, but not routine (familiar) stimuli. The distinct pattern of findings suggests a dysregulation of activation across left and right hemispheres during initial attention and preparatory phases of information processing, in particular, in patients with schizophrenia.
Lee
K H
KH
The Brain Dynamics Centre, Westmead Hospital, NSW 2145, Westmead, Australia. kwangl@psych.usyd.edu.au
Williams
L M
LM
Haig
A
A
Goldberg
E
E
Gordon
E
E
D000328:Adult; D001288:Attention / Q000502:physiology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008606:Mental Processes; D009415:Nerve Net / Q000502:physiology; D012559:Schizophrenia / Q000503:physiopathology*