Objectives: Frontal and lateralized schizophrenia disturbances were examine
d in terms of arousal-modulated changes in 40 Hz Gamma activity.
Methods: Forty patients with schizophrenia and 40 age- and gender-matched c
ontrols were studied in a conventional auditory ERP oddball paradigm, We in
vestigated sub-averaged Gamma activity based upon a simultaneous measure of
electrodemal skin conductance response (phasic arousal) to differentiate n
ovelty (large responses) from routinization (small or no responses). Both e
arly Gamma (Gamma 1) and later induced Gamma (Gamma 2) activities were exam
Results: Patients with schizophrenia (compared with controls) had significa
ntly reduced Gamma I amplitude in the right hemisphere for novelty processi
ng and delayed Gamma 2 latency in the left hemisphere for both novelty and
routinization. Overall, reduced Gamma I amplitude in patients with schizoph
renia was also evident.
Conclusions: These findings indicate that the normal laterality of Gamma ac
tivity 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 init
ial attention and preparatory phases of information processing, in particul
ar, in patients with schizophrenia. (C) 2001 Elsevier Science Ireland Ltd.
All rights reserved.