The physiological interpretation of electrical stimulation of the nervous system.

The physiological basis of the responses of cells in the nervous system to electrical stimulation is described by reference to the strength-duration curve and to the characteristics of ion-carriers in the cell membranes. The effects of the electrode systems used to deliver the electrical stimuli are considered briefly, followed by an account of the relative electrical excitability of nervous elements in peripheral nerves, spinal cord and the cellular nuclei of the nervous system. The responses of more complex physiological systems to both peripheral and central electrical stimulation are then considered, with more detailed reference to neural mechanisms involved in analgesia at peripheral, spinal and brain-stem levels.