Abraham Zangen and Markus Heilig
The pathophysiology of addiction involves impaired excitability and function of reward-related circuitries. Repeated electromagnetic stimulation of these circuitries can induce lasting alterations in excitability and function of these networks, thereby becoming a potential therapeutic approach. Our animal studies revealed that multiple sessions of localized stimulation of the prefrontal cortex can alter molecular and behavioral features of cocaine addiction.
In order to affect the relevant circuitries without a surgery, we have designed special transcranial magnetic stimulation (TMS) coils that enable stimulation of much deeper regions relative to those directly affected by standard TMS. These coils, termed H-coils, were tested for their safety and ability to reach deeper brain regions, and evaluation of their antidepressant potential when applied over the prefrontal cortex of medication-resistant depressive patients showed high rates of remission in a large multi-center study. The therapeutic potential of other versions of H-coils are evaluated in several psychiatric disorders including addiction. The use of an H-coil version targeting the prefrontal and insular cortices in heavy smokers showed effectiveness when high, but not low frequency was applied, especially when combined with activation of the craving-related circuitries by presentation of smoking cues just prior each stimulation session.
Deep TMS is a relatively novel tool in psychiatric and basic brain research. The ability to induce non-surgical direct stimulation of deep brain areas opens a wide range of therapeutic and research options. Optimization of stimulation parameters requires further investigation into mechanisms utilizing imaging and electrophysiological techniques.