Effects of transcranial direct current stimulation (tDCS) on sensory evoked potentials

Abstract

We present a combined experimental/computational modeling approach aimed at studying the effects of transcranial Direct Current Stimulation (tDCS) on neuronal systems. More particularly, we introduce i) a neural mass model (neuronal population level) of the cerebral cortex and ii) a coupling model between the considered neuronal population and an externally-applied electric field. We then use this computational modeling approach to interpret evoked potentials (EPs) recorded from the somatosensory cortex of the rabbit under tDCS. Results showed that the model could accurately reproduce the time-course of actual EPs (polarity and latency of main peaks) recorded under control (i.e. “no tDCS stimulation”) condition. From real data, we also identified the “major” effects of tDCS on EPs in terms of shape modifications and we studied the necessary and sufficient conditions for which the model could reproduce these effects. We found that pyramidal cells should be depolarized (resp. hyperpolarized) in order to simulate the effects of anodal (resp. cathodal) currents. We also found that some interneurons are sensitive to externally-applied fields, indicating that modelling efforts need to also consider the role of these neurons to fully understand interactions between stimulation currents and underlying neuronal systems