Background:
Our integrative neuroscience model of first-episode schizophrenia (FES) emphasizes a dysfunction in the coordinated neural activity required for selective attention in the disorder. This study investigated the longitudinal changes in neural connectivity (assessed by means of 40-Hz gamma synchrony) and neuroanatomy [assessed by magnetic resonance imaging (MRI)] exhibited by patients with FES.
Method:
Twenty-three FES patients underwent an EEG recording in response to an auditory oddball task, both at baseline and 2–3 years subsequently. Gamma-phase synchrony was extracted from the EEG signal for L/R frontal, temporal and posterior brain regions. Thirteen of these patients also underwent an MRI scan at baseline and follow-up, and an automated masking procedure was used to calculate the GM volumes of the analogous cortical regions. A 2 × 6 (‘time’ × ‘region’) repeated-measures ANOVA was used for statistical analysis.
Results:
An inverse relationship was observed between the longitudinal changes in gamma synchrony and the longitudinal changes in GM volume. While the patients with FES lost significant frontal and parietal GM over the follow-up interval, they also showed a corresponding increase in posterior gamma-phase synchrony.
Conclusions:
These results indicate that while gamma-phase synchrony increases over the initial years of illness in patients with FES, GM volume decreases in corresponding cortical regions. Given the role that gamma-phase synchrony has been proposed to play in the integration of discrete perceptual events, these findings support the idea that schizophrenia is caused by a dysfunction in neural connectivity.
