Spatiotemporal after-effects of transcranial direct current stimulation onsensory-evoked activity in rat S1: A pilot VSDI study

For decades, transcranial direct current stimulation (tDCS) has been used to manipulate cortical excitability and plasticity of the human brain. Promising therapeutic results, such as depression treatment, have emerged and are extensively studied today. However the underlying cortical mechanisms of this electrical stimulation remain unclear. Here, we propose to use voltage-sensitive dye imaging (VSDI) on rat primary somatosensory cortex to study the after-effects of tDCS on neuronal population activity. We found that after repetitive anodal tDCS, sensory-evoked VSD responses were significantly increased in amplitude and spatial extent of activation, counteracting the sensory adaptation process observed in control rats. Combining tDCS and VSDI, offers an excellent tool for observing in real-time subthreshold tDCS effects over a large cortical area, when applied to the animal brain.