Transcranial magnetic stimulation and the human brain: an ethical evaluation

Transcranial magnetic stimulation (TMS) is a neuroscientific technique that induces an electric current in the brain via application of a localized magnetic field pulse. The pulse penetrates the scalp and skull non-invasively and, depending on the parameters of stimulation, facilitates or depresses the local neuronal response with effects that can be transient or long lasting. While the mechanisms by which TMS acts remain largely unknown, the behavioral effects of the stimulation are reproducible and, in some cases, are highly beneficial. As the applications of and access to this technique become increasingly pervasive, scientific engagement is needed to define the ethical framework in which research with TMS should be translated to application. In this chapter we review the technique in detail and discuss safety as the paramount ethics issue for TMS. We further examine the ethical arguments for and against neuroenhancement with TMS and how the framework for acceptable practice must differ for patient and non-patient populations.