Early visual processing and adaptation as markers of disease, not vulnerability: EEG evidence from 22q11.2 deletion syndrome, a population at high risk for schizophrenia

Abstract

We investigated visual processing and adaptation in 22q11.2 deletion syndrome (22q11.2DS), a condition characterized by an increased risk for schizophrenia. Visual processing differences have been described in schizophrenia but remain understudied early in the disease course. Electrophysiology was recorded during a visual adaptation task with different interstimulus intervals to investigate visual processing and adaptation in 22q11.2DS (with (22q+) and without (22q-) psychotic symptoms), compared to control and idiopathic schizophrenia groups. Analyses focused on early windows of visual processing. While increased amplitudes were observed in 22q11.2DS in an earlier time window (90-140 ms), decreased responses were seen later (165-205 ms) in schizophrenia and 22q+. 22q11.2DS, and particularly 22q-, presented increased adaptation effects. We argue that while amplitude and adaptation in the earlier time window may reflect specific neurogenetic aspects associated with a deletion in chromosome 22, amplitude in the later window may be a marker of the presence of psychosis and/or of its chronicity/severity.

Fig. 1. Visual adaptation task.

Checkerboards were presented for 33 ms. In five blocked conditions, the ISI was either 145, 245, 495, 995, or 2495 ms.

Fig. 2. CT 22q and 22q: Averaged ERPs and topographies per group and ISI.

A Averaged ERPs per group (CT 22q and 22q) and ISI at O1, Oz, and O2. B Plots showing distribution of amplitudes (trial-by-trial data; average of O1, Oz, and O2) for the time windows of interest (90–140 ms and 165–205 ms). C Averaged ERPs for both groups at Oz. D Topographies for windows of interest per group and ISI.

Fig. 3. Curves representing visual adaptation effects between groups.

Curves representing visual adaptation effects between groups in the time windows of interest (90–140 ms and 165–205 ms). Error bars represent standard errors of the mean.

Fig. 4. CT SZ and SZ: Averaged ERPs and topographies per group and ISI.

A Averaged ERPs per group (CT SZ and SZ) and ISI at O1, Oz, and O2. B Plots showing distribution of amplitudes (trial-by-trial data; average of O1, Oz, and O2) for the time windows of interest (90–140 ms and 165–205 ms). C Averaged ERPs for both groups at Oz. D Topographies for windows of interest per group and ISI.

Fig. 5. 22q− and 22q+: Averaged ERPs and topographies per group and ISI.

A Averaged ERPs per group (22q− and 22q+) and ISI at O1, Oz, and O2. B Plots showing distribution of amplitudes (trial-by-trial data; average of O1, Oz, and O2) for the time windows of interest (90–140 ms and 165–205 ms). C Averaged ERPs for both groups at Oz. D Topographies for windows of interest per group and ISI.

Fig. 6. ERPs and adaptation summary per group and ISI.

A Averaged ERPs per group (CT 22q, 22q−, 22q+, and SZ) at Oz, showing the average of all ISIs. B Curves representing visual adaptation effects between groups (CT 22q, 22q−, 22q+, and SZ) in the time windows of interest (90–140 ms and 165–205 ms). Error bars represent standard errors of the mean.