Exploring visual processing of illusory contours in 22q11.2 deletion syndrome using high density EEG

In order to investigate the electroencephalographic (EEG) biomarkers of visual processing of illusory contours in schizophrenia, we studied patients with 22q11.2DS who are known to have 30% risk for developing schizophrenia in adulthood. This is much higher than the 1% risk in the general population and makes them a group with a high risk profile for schizophrenia. We performed high-density EEG source imaging to study the visual processing in response to illusory contours in 14 participants with 22q11.2DS and 15 age-matched healthy controls in the age range of 14 to 28 years. Two circle and square shapes were used that would form or not form an illusory contour. We found impairments at all the latencies for the 22q11.2DS, such as the P1, N1, Ncl and the visual P3. However, compared with controls, the patient group showed a good performance and significantly faster RT, that could be explained by overactivity of the DLPFC and the ACC, which may play a compensatory role. Moreover, there were also faster RTs and overactivity in the ACC in response to the illusory contours in both groups that could show the role of the ACC in attentional guiding towards relevance detection..