Fig. 6. Contribution of specific neurons and pathways to movement.

a, Schematic showing the anatomical location of neurons and neural pathways that we targeted using intersectional genetics.

b, Reconstructed sequence of leg kinematics during walking while a red-shifted light (4 LEDs) is delivered over the spinal cord to silence reticulospinal tract projections. The occurrence of stance phases and paw dragging events is displayed for both legs below leg kinematics.

c, Bar plots reporting gait parameters most affected by the silencing of reticulospinal fibers (n = 3 mice, two-sided unpaired t-test***,p <0.0001, mean±s.e.m.)

d, Reconstructed sequence of leg kinematics during walking while a red-shifted light (4 LEDs) is delivered over the spinal cord to silence corticospinal tract projections. The occurrence of stance phases and paw dragging events is displayed for both legs below leg kinematics.

e, Bar plots reporting gait parameters most affected by the silencing of corticospinal tract fibers (n = 3 mice, two-sided unpaired t-test ***, p < 0.0001, mean±s.e.m.)

f, Timeline of experiments for targeted expression of Jaws (inhibition) or Chrimson (activation) in V2a interneurons. Photograph shows kinematic recordings during swimming along a water corridor.

g, Reconstructed sequence of left and right leg kinematics during swimming are shown in conjunction with the oscillations of both legs. Grey shared areas indicate the occurrence of a stroke. V2a interneurons were silenced or activated with sudden photostimulation over the lumbar spinal cord (620nm/590 nm, 4 LEDs).

h, Polar plot reporting the coordination between left and right strokes during swimming under the different experimental conditions (n = 3 mice)

i, Timeline of experiments for targeted expression of Jaw in PV^ON neurons of the dorsal root ganglia in mice.

j, Reconstructed sequence of leg kinematics during stepping together with EMG activity of the tibialis anterior muscle while a red-shifted light (4 LEDs) is suddenly delivered over the spinal cord to silence proprioceptive neurons

k, Bar plots reporting the step length, step height, and features of tibialis anterior EMG activity (n = 3 mice, two-sided unpaired t-test; *, p < 0.05; **, p < 0.01, ***, p<0.001, mean±s.e.m.)