MEG does not reveal impaired sensory gating in first-episode schizophrenia.
OBJECTIVE
The inability to adequately suppress the second of two identical stimuli is called sensory gating deficit and can be studied by recording evoked potentials to auditory stimuli, e.g. the P50 and the N100. It has been considered the physiological correlate of schizophrenia patients' perception of being flooded by sensory impressions. According to the notion that the gating deficit constitutes a genetic trait, we expected to demonstrate the phenomenon in first-episode schizophrenia patients by using Magnetencephalography (MEG).


METHODS
Eighteen inpatients in remission of their first psychotic episode and 24 healthy, age- and sex-matched control subjects participated in the study. Diagnoses, psychopathology, and handedness were assessed with established instruments. Stimulation was performed with the double click paradigm (ISI 500 ms, ITI 9-10 s). MEG recordings of 15 patients and 18 controls entered further analyses with the software BESA for spatio-temporal source analyses and statistical analyses with MATLAB.


RESULTS
Neither P50 nor N100 responses differed statistically between the groups, which means that gating was not impaired in this sample of first-episode schizophrenia patients.


CONCLUSIONS
These results are not in line with the majority of studies on sensory gating in schizophrenia, however, studies on first-episode patients are scarce. The most likely reasons for not observing a gating deficit in our study are patients' first-episode status and atypical antipsychotic medication.
Bachmann
Silke
S
Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospitals Halle/Saale, Julius-Kühn-Str. 7, 06112 Halle (Saale), Germany. silke.bachmann@medizin.uni-halle.de
Weisbrod
Matthias
M
Röhrig
Miriam
M
Schröder
Johannes
J
Thomas
Christine
C
Scherg
Michael
M
Rupp
André
A
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D004558:Electric Stimulation / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D020233:Gait Disorders, Neurologic / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000150:complications* / Q000175:diagnosis