The windfalls of technology in the oculomotor system. Proctor lecture.

The single, most important technical advance in all of motor physiology was the development, by the late Ed Evarts at the National Institute of Mental Health, of the method of recording from single neurons in alert, behaving animals. A chamber is implanted over a trephine hole in the skull through which, upon recovery, metal microelectrodes can be advanced to any region within the skull to record the extracellular spikes generated by its neurons. Prior to this, motor physiologists could study motor behavior in unanesthetized animals only after lesions or the chronic placement of fixed stimulating electrodes—both techniques useful for localization, but only in a gross way. Electrophysiology required anesthesia and largely permitted only circuit tracing as an adjunct to anatomical techniques. At the heart of motor physiology is the question of how sensory signals are processed by neurons to become motor commands. Signal processing is at the heart of understanding, and Evarts allowed us to see these signals for the first time.