Neural-Ensemble Activity of Spinal Cord L1/L2 During Stepping in a Decerebrate Rat Preparation

Abstract

Interneuronal networks within the L1-L2 region of the spinal cord are intrinsically capable of coordinating the activation of multiple functional muscle groups as required for locomotion. This paper demonstrates the use of microelectrode arrays for mapping extracellular spike activity and local-field potentials in the lumbar spinal cord of rats. Locomotion was studied in acute decerebrate rats by stimulation of the mesencephalic locomotor region (MLR) to induce stepping. Neural-ensemble activity during stepping was correlated with electromyograms (EMG) from ankle flexors and extensors. To visualize the activity, spatiotemporal population maps were generated from the recorded step cycles. These results will shed light on the organization of locomotor pattern generating circuits and identify active regions for stimulation. In future studies, we will test patterned electrical stimulation of the identified hotspots in spinal-cord-transected rats. These efforts will be directed towards the development of a functional stimulator for locomotion in paralyzed patients