Capabilities of a penetrating microelectrode array for recording single units in dorsal root ganglia of the cat.

The recording capability of a microelectrode array in the cat dorsal root ganglion (DRG) was studied in 11 acute experiments, 373 single, discriminable sensory units were recorded on 587 electrodes (0.64 units/electrode). Sensory action potentials as large as 1750 microV were obtained (mean=132 microV). These were comparable to literature reports of the best DRG extracellular recordings made with conventional electrodes. We were able simultaneously to activate and record over 50 discriminable, time-varying units from L6 and L7 DRGs during a cyclic ankle displacement. We also successfully recorded stable, phase dependent multiple sensory units with very little artifact or electromyographic (EMG) contamination during decerebrate walking. Thus, the array is capable of recording more effectively from more DRGs neurons than has been achieved by conventional recording techniques. The recording selectivity and stability of the array, coupled with the large number of neurons that can be recorded simultaneously, provide attractive features for better understanding sensorimotor control principles.