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Free keywords:
ERFs; Face processing; First-episode psychosis; M170; MEG; Mooney faces
Abstract:
Schizophrenia is characterized by dysfunctions in neural circuits that can be investigated with electrophysiological methods, such as EEG
and MEG. In the present human study, we examined event-related fields (ERFs), in a sample of medication-naive, first-episode schizo-
phrenia (FE-ScZ) patients (n ϭ 14) and healthy control participants (n ϭ 17) during perception of Mooney faces to investigate the
integrity of neuromagnetic responses and their experience-dependent modification. ERF responses were analyzed for M100, M170, and
M250 components at the sensor and source levels. In addition, we analyzed peak latency and adaptation effects due to stimulus repetition.
FE-ScZ patients were characterized by significantly impaired sensory processing, as indicated by a reduced discrimination index (AЈ). At
the sensor level, M100 and M170 responses in FE-ScZ were within the normal range, whereas the M250 response was impaired. However,
source localization revealed widespread elevated activity for M100 and M170 in FE-ScZ and delayed peak latencies for the M100 and M250
responses. In addition, M170 source activity in FE-ScZ was not modulated by stimulus repetitions. The present findings suggest that
neural circuits in FE-ScZ may be characterized by a disturbed balance between excitation and inhibition that could lead to a failure to gate
information flow and abnormal spreading of activity, which is compatible with dysfunctional glutamatergic neurotransmission.
