CHEMICAL AND ELECTRICAL-STIMULATION INDUCE RHYTHMIC MOTOR-ACTIVITY INAN IN-VITRO PREPARATION OF THE SPINAL-CORD FROM ADULT TURTLES

Bath application of N-Methyl-D-aspartate (NMDA) and serotonin induced rhythmic activity in hindlimb motoneurons in an isolated spinal cord p reparation from adult turtles. Subthreshold concentrations of NMDA and serotonin accompanied by stimulation of the dorsal funiculus also ind uced rhythmic activity. The induced activity in motoneurons and ventra l roots displayed characteristics which resemble that of locomotion. T his activity could be evoked in as few as three segments (D8-D10) of t he lumbar enlargement isolated from the rest of the spinal cord. The e xistence of intrinsic oscillations in single neurons was revealed in t he presence of tetrodotoxin. Our findings introduce a new in vitro pre paration in which electrophysiological and pharmacological tools can b e used with ease to study mechanisms of central pattern generation in a mature spinal motor network. (C) 1998 Elsevier Science Ireland Ltd.