A technique to restrain awake rats for recording single-unit activity with glass micropipettes and conventional...

A technique has been developed which permits the study of single-unit activity using glass micropipettes and conventional microdrives in restrained, awake rats. A unique feature of this preparation is that the rats are kept still during electrophysiological recording by infusing a small amount of local anesthetic through a catheter chronically implanted into the epidural space of the spinal cord resulting in a temporary mid-body to hind-limb motor blockade. The animal is held in a slightly modified stereotaxic device by a bolt attached to the top of its skull. The rats are responsive to acoustic, visual, or tactile stimulation, permitting the simultaneous recording of electrophysiological activity and behavioral or electromyographical activity rostral to the level of motor blockade. By employing the epidural anesthesia the animals are healthy and mobile prior to and following each recording session and can be tested across a number of days. Single unit activity recorded from the facial motor nucleus in response to an acoustic click is presented as an example of the viability of this preparation. Therefore, this preparation seems suitable for a variety of investigations involving neurophysiological recording with glass micropipettes or the correlation of such recording with simple behaviors in awake, restrained rats.