Alpha-gamma interactions are disturbed in schizophrenia: a fusion of electroencephalography and functional magnetic resonance imaging.

OBJECTIVE

To delineate regional brain activity associated with the alpha oscillations related to perception of sensory stimuli, and test the hypothesis that the synchronisation of alpha oscillations with stimulus onset is impaired in schizophrenia.

METHODS

Joint independent component analysis was applied to electroencephalographic and functional magnetic resonance imaging data recorded in 19 individuals with schizophrenia and 19 healthy individuals during a vibrotactile somatosensory task.

RESULTS

In healthy individuals the strongest component was dominated by alpha oscillations, and was associated not only with activity in somatosensory regions but also in the insula and anterior cingulate cortex (the salience network). In schizophrenia, the strongest component had low alpha power and activity was limited mainly to somatosensory regions. Furthermore, in the healthy group, but not the patients, significant correlation was observed between the strongest component and evoked gamma power.

CONCLUSION

The correlation between the alpha-dominated component and evoked gamma power is consistent with the hypothesis that gamma localised to sensory cortex elicits stimulus-locking of spatially distinct, large-scale ongoing alpha oscillations. Furthermore, this hypothesised mechanism appears to be disrupted in schizophrenia.

SIGNIFICANCE

These findings suggest that a weakened alpha-gamma interaction underlies impaired recruitment of the brain during sensory information processing in schizophrenia.