The Relation of Brain Electrical Activity to Behavior

Electrophysiological studies of the brain in mammals have made extensive use of immobilized preparations. Experimental animals are commonly anesthetized or immobilized by curare or by section of the brain stem (cerveau isol�) (Bremer, 1935) or spinal cord at level CI (enc�phale isol�) (Bremer, 1936a, b). Such preparations are preferable to freely moving animals for many types of research since they simplify the technical problems of electrical recording and make it easy to record or control physiological variables, such as blood pressure or blood gas concentrations. Some procedures, such as intracellular recording, are virtually impossible unless the preparation is rigidly immobilized. Furthermore, since animals that have been anesthetized or had the neuraxis transected have a greatly reduced capacity to feel pain, many procedures that could not be used in intact, conscious animals can be carried out freely.