High Schizotypy shows superior putative subcortical Magnocellular-driven emotion processing and deficits in cortical attentional change detection

• ¹ La Trobe University, School of Psychological Science, Australia

Background
Attention deficits are well established as a major area of impairment in schizophrenia. Furthermore, some visual and attentional deficits have been found in relatives and individuals with high schizotypy personality traits, suggesting the existence of a potential biomarker for schizophrenia.
We sought to explore the relationship between schizotypy traits and the magnocellular (M) pathway and dorsal stream – argued to be impaired in schizophrenia. Face emotion processing was also explored under conditions targeting low (M) or high (parvocellular) spatial frequency channels.

Methods
Sixty-one non-clinical participants completed the Schizotypy Personality Questionnaire (SPQ), and on this basis were grouped into High and Low SPQ groups. M-pathway processing was assessed by a flicker-defined form contrast threshold task, dorsal stream processing was assessed by motion coherence and time to detect visual array change, whilst form coherence provided a control measure of ventral stream processing. An emotion categorization task measured accuracy for identifying disgust, happy or neutral emotional faces that had either low- or high-pass filters applied, creating high (HSF) and low spatial frequency (LSF) conditions, respectively.

Results
Although not significant, the High SPQ group showed superior flicker-defined form contrast thresholds, and worse motion coherence thresholds compared with the Low SPQ group. Form coherence thresholds did not differ between groups. However, the High SPQ group showed significantly worse change detection performance. ANOVA results for comparison of SPQ group, emotion and spatial frequency revealed a three-way interaction. Simple effects analysis revealed that whilst both groups showed lower accuracy for disgust compared with neutral and happy emotions, the High SPQ group showed higher accuracy compared with the Low SPQ group for LSF disgust emotions.

Discussion
Results suggest schizotypy may be associated with superior subcortical M-pathway processing but deficits in dorsal stream and transient attention. These results may explain the relative superiority for detecting LSF disgust emotions – assuming this stimulus requires subcortical M-pathway activation to the amygdala. We suggest a straightforward M- or dorsal deficit does not account for the anomalous processing in high schizotypy. Further work should explore how hypoactive M-pathway activation could detreminetally impact ability to disengage visual attention mechanisms.