Neuromodulation, defined by the
International Neuromodulation Society as "the alteration of nerve activity through the delivery of electrical stimulation or chemical agents to targeted sites of the body," is carried out to normalize – or modulate – nerve function. Neuromodulation is an evolving therapy that can involve a range of electromagnetic stimuli such as a strong magnetic field (
repetitive transcranial magnetic stimulation), a very small
electric current, or a drug instilled directly in the subdural space (intrathecal drug delivery). Emerging applications involve targeted introduction of genes or gene regulators and light (
optogenetics), and by 2014, these had been at minimum demonstrated in mammalian models, or first-in-human data had been acquired. The most clinical experience has been with electrical stimulation.