Does Transcranial Electrical Stimulation Induce Changes in Peripheral Physiology?

Transcranial electrical stimulation (tES) is a non-invasive brain stimulation method that has evoked increasing interest during the past years. The most common form of tES, transcranial direct current stimulation (tDCS), is considered to modulate neuronal resting potentials. For example, anodal stimulation over motor cortex appears to lead to increased neuronal excitability under the stimulation electrodes. However, some recent findings suggest that the effects of tDCS extend beyond the cortical areas under the electrodes, to deeper brain structures such as the midbrain. The brain also actively regulates peripheral physiology. Thus, changes in brain activity following tES may lead to modulation of peripheral physiology. For example, tDCS targeting primary motor cortex has been observed to induce changes in peripheral glucose metabolism. Furthermore, stimulation of dorsolateral prefrontal cortex has been shown to lead to alterations in cortisol secretion and the activity of the autonomic nervous system. Unpublished findings from our group corroborate with the above observations. Nevertheless, the evidence regarding peripheral effects of tES remains limited. Investigating such possible effects may be relevant especially from the point of view of tES safety and potential therapeutic discoveries. Disclosure of interest The author has not supplied his declaration of competing interest.