Changes in Event-Related Desynchronization and Synchronization during the Auditory Oddball Task in Schizophrenia Patients

Abstract

Objective: We studied differences in the spatiotemporal dynamics of cortical oscillation across brain regions of patients with schizophrenia and normal subjects during the auditory oddball task using magnetoencephalography (MEG) and electroencephalography (EEG).

Methods: Ten right-handed male schizophrenia patients were studied. We used a newly developed adaptive spatial filtering algorithm optimized for robust source time-frequency reconstruction of MEG and EEG data, and obtained consecutive images in functional maps of event-related desynchronization (ERD) and synchronization (ERS) in theta, lower alpha (8-10 Hz), upper alpha (10-13 Hz), and beta bands.

Results: Beta ERD power at 750-1000 ms in patients was significantly increased in large right upper temporal and parietal regions and small upper portions of bilateral dorsal frontal and dorsal-medial parietal regions. Theta ERS power in schizophrenic patients during the oddball task was significantly increased in the left temporal pole at 250-500 ms, and was significantly increased in dorsal, medial frontal, and anterior portions of the anterior cingulate cortex in both hemispheres, and the left portion of lateral temporal regions at 500-750 ms, compared to the control group (family-wise error correction p<0.05). Lower alpha ERS power was significantly decreased in the right occipital region at 500-750 ms and in the right midline parietal and bilateral occipital regions at 750-1000 ms. Upper alpha ERS power was significantly decreased in right midline parietal and left occipital regions at 750-1000 ms.

Conclusions: ERD/ERS changes were noted in the left temporal pole and midline frontal and anterior cingulate cortex in theta ERS, occipital lobe in alpha ERS, and right temporal-frontal-parietal, midline frontal, and anterior cingulate cortex in beta ERD. These findings may reflect disturbances in interaction among active large neuronal groups and their communication with each other that may be related to abnormal cognitive and psychopathological function.

Significance: Study of ERD and ERS by time-frequency analyses using MEG is useful to clarify data processing dysfunction in schizophrenia.

Keywords: Magnetoencephalography; P300.; event-related desynchronization; event-related synchronization; oddball task; schizophrenia.

Fig. (1)

(A) We arbitrarily chose the 104 channel as an example from 160 channels. (B). Grand average of time frequency map of schizophrenic patient group (n=10) during the odd ball task in channel 104. (C). Grand average of time frequency map of control group (n=10) during the odd ball task in channel 104. Beta ERD was increased in patients group compared to controls during the odd ball task.

Fig. (2)

(A) Grand average of time frequency map of schizophrenic patient group (n=10) at phase-lock during the odd ball task in channel 104. (B) Grand average of time frequency map of control group (n=10) at phase-lock during the odd ball task in channel 104. Power was not found at phase-lock in all frequencies compared to at no phase-lock, as shown Figs. (1B and 1C) in both patient and control groups.

Fig. (3)

Theta ERS. (A). Functional maps of ERS power in the theta band (4–8 Hz) during the oddball task show statistical differences between patients with schizophrenia and normal controls. Theta ERS at 250–500 ms in patients was significantly increased in the left temporal pole during oddball task (FWE p<0.05). (B). Theta (4–8 Hz) ERS power at 500–750ms in patients was significantly increased in midline frontal and anterior portion of anterior cingulate cortex regions in both hemispheres, and left portion of lateral temporal regions during the oddball task (FWE p<0.05).

Fig. (4)

Alpha ERS. (A) Lower alpha (8–10 Hz) ERS power at 500–750ms in patients was significantly decreased in the right occipital region during the oddball task (FWE p<0.05). (B) Lower alpha (8–10 Hz) ERS power at 750–1000 ms in patients was significantly decreased in the right midline parietal and bilateral occipital regions during the oddball task (FWE p<0.05). (C) Upper alpha (10–13 Hz) ERS power at 750–1000ms in patients was significantly decreased in the right midline parietal and left occipital regions during the oddball task (FWE p<0.05).

Fig. (5)

Beta ERS and beta ERD. (A). Beta (13–30 Hz) ERS power at 500–750ms in patients was significantly decreased in the right occipital region during the oddball task (FWE p<0.05). (B). Beta (13–30 Hz) ERS power at 750–1000ms in patients was significantly decreased in the region from right frontal to temporal and right anterior portion of anterior cingulate cortex during the oddball task (FWE p<0.05). (C). Beta ERD power at 750–1000 ms in patients was significantly increased in the right posterior frontal, upper temporal, and parietal region, and small upper portions of bilateral dorsal frontal and dorsal-medial parietal regions, compared to control subjects (FWE p<0.05).