Reaching deep brain structures: The H-coils

Abstract

The capacity of standard transcranial magnetic stimulation (TMS) to elicit neuronal responses is limited to superficial structures. The deep TMS technology enables direct stimulation of deeper and larger brain volumes, potentially affecting extensive neuronal pathways including deeper cortical regions and fibers targeting subcortical regions, without a significant increase of the electric field induced in superficial cortical layers. This chapter includes theoretical background and design principles of deep TMS H-coils, comparison of standard TMS and deep TMS coils electric field profiles, as well as description and maps of electric field distribution of several deep TMS H-coils.