Oades, R. D., Jemel, B., Achenbach, C., Wiemer, P., Schreiber, S., Kreul, K., & Röpcke, B., (2002)
Change detection: altered asymmetry of frontal mismatch sources in adolescent schizophrenia.
Schizophrenia Research 53, (supplement) p. 89.

Introduction: Mismatch negativity (MMN) is an event-related potential elicited by a rare deviant sound that is compared with common standard sounds or tones. Its amplitude is reduced in non-paranoid patients with schizophrenia (usually with predominant negative symptoms) more than in the paranoid forms of schizophrenia (1).
We describe dipole source models for MMN generators in the temporal and frontal lobes - fitted to Talairach space - and, in a preliminary analysis, compare the source current density topographic distributions in young patients with early onset schizophrenia, less than 18 years of age (see also 2)

Methods: MMN was recorded from 32 leads in a three-tone auditory oddball paradigm using pitch/frequency and duration deviants.

Results:
First: Similar dipole sources were found for the two types of deviant tones in healthy subjects
Secondly: There were bilateral teemporal lobe dipoles, with that on the right being more lateral and deeper.
Thirdly: Anterior inferior frontal lobe sources on the right contrasted with more posterior dipoles in the anterior cingulate cortex on the left.
Fourthly, Current density analysis in the patients showed a smaller MMN that had shifted towards the left -- this implies a weaker contribution from the right hemisphere.

Conclusions: We point out that the right frontal sources in normal healthy subjects are at sites close to where brain-imaging studies have found activity relating to preconscious visual change detection (3). Further, electrophysiological and anatomical changes have also been reported previously for the right hemisphere in patients with an early onset of schizophrenia (4).
(1) Oades et al.,. 1997 Biol. Psychiat., 41, 1196-1210.
(2) Jemel et al.,. 2001 NeuroImage, 13, 323.
(3) Beck et al., 2001 Nature Neurosci., 4, 645-650.
(4) Matsumoto et al., 2001 Am. J. Psychiat., 158, 1299-1304.
For some of the figures illustrating the results from healthy subjects, see: Oades RD, et al., (2001). Sources of prefrontal activity for auditory working memory (MMN): evidence for an impaired fronto-temporal lobe dialogue in schizophrenia. Eighth International Congress: Schizophrenia Research, [Latebreaking data], Whistler, B.C., Canada