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Cereb Cortex. 2016 Mar;26(3):1027-1035. doi: 10.1093/cercor/bhu278. Epub 2014 Dec 1.

Differential Alterations of Auditory Gamma Oscillatory Responses Between Pre-Onset High-Risk Individuals and First-Episode Schizophrenia.

Author information

1
Department of Neuropsychiatry, Graduate School of Medicine.
2
Office for Mental Health Support, Division for Counseling and Support.
3
Department of Youth Mental Health, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan.
4
Department of Electrical Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8530, Japan.
5
Japan Science and Technology Agency (JST), National Bioscience Database Center (NBDC), Kawaguchi-shi, Saitama 332-0012, Japan.

Abstract

Alterations in gamma-band auditory steady-state response (ASSR) are the most robust finding of abnormal neural oscillations in patients with first-episode (FES) and chronic schizophrenia. Gamma-band ASSRs may indicate GABAergic interneuron dysfunction. Nevertheless, it is unknown whether abnormal gamma-band ASSRs are present before the onset of psychosis. Subjects were 15 ultra-high-risk (UHR) individuals, 13 FES patients, and 21 healthy control (HC) subjects. We performed electroencephalogram recordings and measured ASSRs in each group as they were presented with click trains at 20, 30, and 40 Hz. We then conducted time-frequency analyses and calculated intertrial phase coherence and event-related spectral perturbation. The time course of gamma-band ASSRs showed significantly different features among groups. Compared with the HC group, the UHR group was characterized by intact early-latency (0-100 ms) and reduced late-latency (300-500 ms) ASSRs. In contrast, both early- and late-latency ASSRs were significantly reduced in the FES group. Gamma-band ASSRs were correlated with clinical symptoms and attentional functioning in FES (|rs| > 0.70). These results suggest differential alterations of gamma-band ASSRs between UHR and FES groups. The late-latency ASSR alteration may represent a biomarker for early detection of psychosis, while the early-latency ASSR abnormality may develop through the onset of psychosis.

KEYWORDS:

auditory steady-state response; electroencephalogram; gamma oscillations; schizophrenia; ultra-high risk

PMID:
25452567
DOI:
10.1093/cercor/bhu278
[Indexed for MEDLINE]

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