Fig. 5.

The mixed flexor and extensor motor output of L4 can be segregated by site-specific focal light stimulation. The L4 root carries a similar amount of motor output to extensor muscles as to the flexor muscles evident as a double burst pattern seen during locomotor-like activity (by whole preparation Vglut2::Cre x RC-ChR2 stimulation in A). The flexor activity in L2 (B, 1) and L4 (B, 2) can be independently activated depending on the site of focal light stimulation. The L4 output in B2 is flexor-related because it has a phase lag to L5 output (left circle plot). The extensor activity in L4 is also demonstrated by yet another stimulation spot (B, 3 and right circle plot).