Unitary premotor drives and modular reflex primitives in frog spinal cord

Modular organization of reflexes and premotor drives in frog spinal cord can be revealed in a number of ways. Isometric force-field measurements, electromyogram decomposition with statistical methods, and direct reflex manipulation all support a small number of elements supporting spinal behaviors. The central neural circuits that support the modules indicated by these methods are not well understood. A current focus of our laboratory is to begin to examine activity patterns that support modular common drives. To examine activity we are using a Bionic Technologies Cerebus 128 channel system with real time (1KHz 1ms resolution) delivery of up to 2 resolved spikes spikes per channel. Neuralynx Cyborg drives, microwire, and tetrodes are being tested for recording with this system. Activity is elicited by reflex stimulation to induce wipe movements or muscle vibration. We are also testing activity induction by photolytic uncaging of glutamate in the preparation, a technique with the advantage of no electrical artefact but perhaps reduced temporal precision. If recruited by microstimulation or other means a modular spinal circuitry may in the future support powerful neuroprosthetic designs.