The Limited Effect of Neural Stimulation on Visual Attention and Social Cognition in Individuals with Schizophrenia
Previous research has demonstrated a relationship between faulty visual attention and poorer social cognition within individuals with schizophrenia. One potential explanatory model for this relationship suggests that faulty neuromodulation in specific neural networks may result in poorer attention to socially important cues, leading to poorer understanding of another’s emotional state or intentions. The current study experimentally manipulated neural networks using tDCS to examine this potential causal mechanism. Using a double-blind crossover design, 74 participants underwent both active and sham stimulation to either the ventral attention network (rTPJ) or the social brain network (dmPFC). Following stimulation, participants completed tasks assessing emotion recognition (ER40; BLERT) and Theory of Mind (TASIT). Concurrent eye tracking assessed visual attention, measuring the proportion of time spent attending to socially and contextually important stimuli. The primary aim of the study was to determine whether stimulation to the rTPJ improves visual attention based upon eye tracking, and secondary aims were to determine 1) whether stimulation improves performance on the social cognitive tasks and 2) whether visual attention moderates this improved performance. For emotion recognition, results failed to support the proposed model, with stimulation impacting neither visual attention nor social cognitive task accuracy. Similarly, neurostimulation failed to impact visual attention on the ToM task. However, we saw significant improvement in ToM accuracy after stimulation to the active comparator, dmPFC, with no improvement after stimulation to rTPJ. Although the current results require replication, this study demonstrates no effect of a single stimulation session on visual attention and emotion recognition accuracy, and via a somewhat limited effect on ToM performance, directly challenges our proposed model for deficits in this social cognitive domain. Instead, findings provide some support for an alternate model, which highlights the importance of executive functions, not visual attention, in ToM within individuals with schizophrenia.