LOCAL-ANESTHESIA INDUCES IMMEDIATE RECEPTIVE-FIELD CHANGES IN NUCLEUSGRACILIS AND CORTEX

THE reorganization of receptive fields of nucleus gracilis neurones af ter local anaesthesia, and its relationship to the reorganization of c ortical maps were studied in the rat. Cutaneous stimulation was perfor med using electronically gated air jets. Single unit recordings were o btained in gracilis nucleus and somatosensory cortex. Temporary anaest hesia was induced with lidocaine (2%, 5-15 mu l s.c.), which blocked t he responses in <2 min and provoked the simultaneous appearance of new overlapping receptive fields in gracilis and cortical neurones in 2-3 0 min. The present results suggest that the early reorganization of so matosensory cortical maps after temporary anaesthesia may be partly du e to the emergence of new receptive fields in nucleus gracilis neurone s.