[Mechanisms of action of high-frequency deep brain stimulation. A review of the literature and current concepts]

High-frequency deep brain stimulation (HF-DBS) has become a widely used therapeutic method in the field of movement disorders for the treatment of Parkinson's disease, essential tremor or dystonia. New targets and indications are under evaluation in several other conditions such as cluster headache, obesity, epilepsy or psychiatric diseases (depression, OCD). However, the mechanisms of action of HF-DBS remain poorly understood. Herein we present a review of the literature and our current view of the question. The first part deals with the effects of stimulation itself on the different parts of the neuron and tries to answer the question of what is actually stimulated by DBS (cell bodies, dendrites or axons). The second part is devoted to the ortho- and antidromic effects of the stimulation. The third part more specifically focuses on the case of subthalamic nucleus stimulation. The target axons in the subthalamic area are discussed in the light of recent optogenetic studies. In conclusion, HF-DBS leads to a kind of functional deafferentation of the stimulated structure and to the modulation of cortical activity (both ortho and antidromically). Which effects are relevant to the therapeutic effects of DBS is still unclear. Further investigations are required especially regarding the corticosubthalamic pathways.