COMBINED INTRACELLULAR STIMULATION AND HIGH-SPEED VIDEO MOTION ANALYSIS OF MOTOR CONTROL NEURONS IN THE COCKROACH

A complete understanding of motor control circuitry requires detailed analysis of the behavior produced by the circuitry as well as the conn ections between individual neurons. A technique is described for combi ning high speed video motion analysis of leg movements in the cockroac h with electrophysiological techniques such as intracellular stimulati on/recording from central neurons and EMG recording from leg muscles. Using a restrained preparation, we have quantified leg movements evoke d by intracellular stimulation of individual motor neurons and local i nterneurons. By incorporating motion analysis into the recording parad igm, the transfer functions from electrical activity to movements can be derived. Because distinct and characteristic responses to single an d multiple action potentials are seen in slow, intermediate, and fast motor neurons, it is often possible to identify the motor neuron targe ts of local interneurons. The ability to analyze movement in any plane is especially useful in situations such as blind neuropilar penetrati ons, where a more restricted motion transducer arrangement may not be in register with the impaled cell. In addition, it is possible to reco rd and analyze such complex phenomena as coordinated movements in mult iple joints produced by local interneurons and reflexes produced by pr oprioceptive feedback due to activity of one motor neuron.