Figure 6.

Extracellular unit recording of hip-extensor interneuron with 0% overlap with the hip-flexor burst was active in a burst during hip-flexor quiescence of normal rostral scratch and was quiet during rostral scratch with a hip-extensor deletion. (A) ENG recordings of the biarticular knee-extensor motor nerve (top trace); ENG recordings of the hip-flexor motor nerve (second trace); instantaneous frequency of unit (third trace); and interneuron unit activity (bottom trace). The first cycle is an example of rostral scratch with a hip-extensor deletion (end of cycle marked with filled diamond). The other cycles are examples of normal rostral scratch. (B) Start and end of bar represent mean ON-phase and mean OFF-phase, respectively, of unit firing during normal rostral scratch. Bar is unfilled to represent unit quiescence during hip-extensor deletion rostral scratch. From⁵⁴ and used with permission of and copyright 2002 by the Society for Neuroscience.