Figure 8.

Population data on motoneuron responses to contralateral peripheral nerve stimulation. A, Incidence of synaptic responses, separated by whether the motoneuron projected to an intrinsic hand muscle (d), forearm flexor (f), forearm extensor (e), or a muscle proximal to the elbow (p). In cells that responded to multiple nerves, the earliest response has been used. B, Same as in A, but now classified according to the contralateral nerve that evoked the response. cMN, Median at the arm; cUN, ulnar at the arm; cDRN, deep radial nerve. C, Venn diagram representation of responses to different contralateral nerves, compiled for motoneurons in which all three nerves were tested. D, Amplitude of synaptic responses elicited by contralateral nerve stimulation, separated by motoneuron target muscle (same abbreviations as in A). The different symbols correspond to the different contralateral nerves stimulated (see key); filled symbols represent IPSPs; and open symbols, EPSPs. Cross hairs to the right indicate mean ± SD of amplitudes for the different MN types. E, Same as in D, but plotting response latencies. Cross hairs to the right indicate the overall mean ± SD of EPSP and IPSP latencies. D, E, All observed responses, including cases where the same motoneuron responded to stimulation of more than one contralateral nerve.