Chronic stimulation of the central nervous system

Historically, chronically implanted neuronal stimulators evolved from cardiac pacemaker technology and began in 1963 with phrenic nerve cyclic activation for long-term artificial respiration. The larger field of pain control started in 1965 with peripheral nerve activating, and in 1967 with spinal cord stimulation. The next 35 years has seen an expansion of its clinical use, particularly in the numbers of channels and outputs. Stimulators are available with outputs being either "controlled current" or "controlled voltage" with or without capacitive-coupling producing monophasic or biphasic, balanced or unbalanced waveforms. Stimulators are powered either by radio frequency applied by a surface antenna or internally by a battery (non-rechargeable or chargeable). A goal of neural prosthesis development is to modulate and restore dysfunction of the nervous system by safely using small electrodes placed close to the neurons to be activated.