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Schizophr Res. 2011 Mar;126(1-3):36-42. doi: 10.1016/j.schres.2010.10.001. Epub 2010 Oct 30.

An MEG study of alpha modulation in patients with schizophrenia and in subjects at high risk of developing psychosis.

Author information

1
Clinical Cognitive Neuroscience Center, Neuroscience Institute, SNU-MRC, Seoul, Republic of Korea.

Abstract

BACKGROUND:

Selective attention involves a dynamic interaction between attentional control systems and brain oscillations. In auditory processing, selective attention toward task-relevant stimuli and the inhibition of irrelevant information can be considered as aspects of top-down attentional control. Oscillatory rhythms in the alpha band have been found to play an important role during top-down processing. Because attention deficits have been noted in patients with schizophrenia, we examined alpha oscillations in schizophrenia and in the prodromal phase of psychosis.

METHODS:

The present study compared alpha oscillations using measures of both spectral power and inter-trial coherence in 17 subjects at ultra-high-risk, 10 patients with schizophrenia, and 18 matched normal control subjects. Whole-head magnetoencephalography (MEG) was conducted during an auditory oddball task to investigate alpha brain activity related to selective attention to target stimuli and selective inhibition of irrelevant stimuli.

RESULTS:

Patients with schizophrenia showed diminished alpha event-related desynchronization compared with the control subjects, while the ultra-high-risk subjects had values intermediate between the control subjects and schizophrenia patients. Similarly, alpha inter-trial phase coherence was lower in the schizophrenia patients than the ultra-high-risk subjects, and lower in the ultra-high-risk subjects than the normal control subjects. Furthermore, alpha band activity in the parieto-occipital region was more severely depressed in the schizophrenia patients than the ultra-high-risk subjects.

CONCLUSIONS:

The altered alpha band activity in the ultra-high-risk group indicates that a deficit in top-down attentional control exists before the onset of psychosis. The alpha event-related desynchronization and inter-trial coherence may reflect a functional decline in the prodromal phase of schizophrenia.

PMID:
21036541
DOI:
10.1016/j.schres.2010.10.001
[Indexed for MEDLINE]

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