[Interactive rTMS protocols in psychiatry].

BACKGROUND

The efficiency of repetitive transcranial magnetic stimulation (rTMS) in the treatment of psychiatric disorders is robust for major depressive episode (MDE) while results are encouraging for schizophrenia. However, rTMS protocols need to be optimized. Basic researches in TMS led to the concept of "state dependency TMS". This concept suggests that the neural circuits' activation states, before and during the stimulation, influence the pulse effect. Indeed, TMS effect must be seen, not simply as a stimulus, but also as the result of an interaction between a stimulus and a level of brain activity. Those data suggest that rTMS efficiency could be increased in psychiatric disorders by triggering patients' neurocognitive activities during stimulation. Thus "interactive rTMS protocols" have been submitted.

OBJECTIVES

This article provides a review and a classification of different interactive protocols implemented in the treatment of MDE and schizophrenia. Protocols' interactions with cognitive activities and brain electrical activities will be discussed.

LITERATURE FINDINGS

Interactive rTMS protocols that manipulate cognitive activities have been developed for MDE treatments. They aim at regulating emotional states of depressed patients during the stimulation. The patients perform emotional tasks in order to activate cortical networks involving the left dorsolateral prefrontal cortex (DLPFC) into a state that may be more sensitive to the rTMS pulse effect. Simultaneous cognitive behavioral therapy ("CBT rTMS") and cognitive-emotional reactivation ("affective rTMS") have thus been tested during left DLPFC rTMS in MDE. Interactive rTMS protocols that manipulate brain electrical activities have been developed for MDE and schizophrenia treatments. Two categories of protocols should be identified. In the first set, personalized brain activity has been analyzed to determine the parameters of stimulation (i.e. frequency of stimulation) matching the patient ("personalized rTMS"). Personalized rTMS protocols can be made "online" or "offline" depending on whether the EEG activity is measured during or prior to rTMS. Online protocol is called "contingent rTMS": it consists in stimulating the brain only when a specific EEG pattern involving the intensity of alpha rhythm is recorded and recognized. Offline protocol is called "alpha rTMS", and relies on ascertaining frequency of stimulation in accordance with personalized alpha peak frequency prior to rTMS. In the second set, electrical brain activity is modulated before or during rTMS in order to stimulate the DLPFC in optimal conditions. Brain activity modulation may be obtained by transcranial direct current stimulation ("tDCS rTMS") or EEG-biofeedack ("EEG-biofeedback rTMS").

CONCLUSION

Interactive rTMS studies have various limitations, notably their exploratory character on a small sample of patients. Furthermore, their theoretical neurocognitive framework justification remains unclear. Nonetheless, interactive rTMS protocols allow us to consider a new field of rTMS, where cognitive and cerebral activities would no longer be considered as simple neural noise, leading to a kind of "first person rTMS", and certainly to innovative therapy in psychiatry.