Schülke, R., Schmitter, C., Straube, B. (2023). Improving Causality Perception Judgments in Schizophrenia Spectrum Disorder via Transcranial Direct Current Stimulation. Journal of Psychiatry & Neuroscience IF: 5.699
Background: Deficient causality perception and attribution may underlie key symptoms of schizophrenia spectrum disorder (SSD), such as delusions and ideas of reference. While transcranial direct current stimulation (tDCS) can increase the influence of spatial information on perceptual causality judgments in healthy subjects, its effect in patients with SSD remains unknown.
Objective: We hypothesized that tDCS modulates the contribution of stimulus characteristics to perceptual causality judgments in SSD patients. We predicted that right parietal tDCS increases the influence of spatial stimulus characteristics on patients’ causality perception judgments.
Methods: SSD patients (n = 19) received frontal, parietal, frontoparietal and sham tDCS in four separate sessions. Pre- and post-tDCS, patients viewed video clips of ball A colliding with ball B. Spatial linearity (ball B’s angle of egress) and temporal contiguity (delay between collision and ball B’s movement) varied parametrically. After each launching event, patients rated perceived causality.
Results: We found a brain region-dependent tDCS effect regarding the sensitivity to violations of spatial linearity. After right parietal anodal tDCS, the influence of angle variations on patients’ perceptual causality judgments increased, reflected by a higher probability of perceived causality for stimuli with small angles and a lower probability of perceived causality for stimuli with high angles.
Conclusion: TDCS increased the influence of spatial stimulus characteristics on causality perception in SSD patients. Future research should explore potential links between tDCS-induced changes in basic perceptual processes and clinical symptoms, such as delusions and ideas of reference.