Multimodal personalization of transcranial direct current stimulation for modulation of sensorimotor integration

Transcranial direct current stimulation (tDCS) for the modulation of smooth pursuit eye movements provides an ideal model for investigating sensorimotor integration. Within neural networks subserving smooth pursuit, visual area V5 is a core hub where visual motion information is integrated with oculomotor control. Here, we applied personalized tDCS explicitly targeting individual V5 in healthy human participants using algorithmic optimization informed by functional magnetic resonance imaging and combined electro- and magnetoencephalography. We hypothesized subtle modulation of sensorimotor integration during pursuit and assessed the effects of personalized anodal and cathodal tDCS targeting V5 compared to (a) sham stimulation, (b) personalized tDCS targeting the frontal eye field (FEF), and (c) conventional normative tDCS over V5. We found pursuit initiation specifically delayed during personalized cathodal tDCS targeting right V5 suggesting the involvement of distinct functional subregions of V5 in initial sensorimotor integration of visual motion information during pursuit eye movements. Results were extensively controlled by anodal and sham tDCS, different pursuit tasks, and finite-element simulations of individual electric fields. Importantly, in contrast to the two control experiments (personalized tDCS targeting FEF and normative tDCS over V5) personalized tDCS targeting V5 effectively modulated pursuit by adapting electric fields to individual anatomical and functional V5 properties. Our results provide evidence for the ability of personalized tDCS targeting V5 to introduce targeted subtle modulation of sensorimotor integration, specifically during smooth pursuit initiation. Further, our results indicate the potential of personalized tDCS to alter behavior as the main aspect of interest in human neuromodulation.