Nicotine induces both behavioral stimulation and anxiety in animals. Transcranial magnetic stimulation shows promise as does transcutaneous supraorbital nerve stimulation. Sensory neurophysiology investigates the relation between the processes of perception and stimulation. Procedures may include bladder distention, nerve stimulation, or surgery. Immature neurons are more prone to synaptic depression than potentiation after high frequency stimulation. Hz resulted in more effective therapeutic stimulation. Natural killer cell activation is determined by the balance of inhibitory and activating receptor stimulation. A non-invasive method using transcutaneous electrical nerve stimulation (TENS) is being studied. The direct electrical stimulation of the brain could simulate electrocortical relays. Conditions that increase automaticity include sympathetic nervous system stimulation and hypoxia. There is tentative evidence of benefit of transcutaneous electrical nerve stimulation (TENS) in RA. Anorgasmia is regular difficulty reaching orgasm after ample sexual stimulation, causing personal distress. Many diseases are investigated through "excitation/stimulation" or "inhibition/suppression" testing. This phenomenon is called intracranial self-stimulation or brain stimulation reward. It is usually the result of sexual stimulation, which may include prostate stimulation.