Fig. 8.

Double-referent mean ON- and OFF-phases (± angular deviation) of 72 descending propriospinal interneurons during normal rostral scratching represented by the start andend, respectively, of each bar. Unit firing during rostral scratching with hip-extensor deletions is indicated by the fill of each bar: unfilled bar for quiescence; gray-filled bar for a burst;black-filled bar for continuous firing. Nearly all units with 0% overlap with hip-flexor activity and with mean ON- and OFF-phases during hip-flexor quiescence of normal rostral scratching were quiet during deletion rostral scratching.