Figure 1. CFA and RFA corticospinal neurons target neurons in distinct spinal regions.

(A) Strategy to label brain-wide inputs to the cervical spinal cord.

(B) Top-down view of a 3D reconstruction of the mouse brain showing CSNs as individual points. A contour map of CSN cell bodies is superimposed. The approximate locations of CFA and RFA are indicated. The three colors indicate samples from 3 separate experiments (N = 3 mice for A and B).

(C) Strategy to simultaneously label CFA and RFA CSNs.

(D) Photomicrograph of a transverse section of the spinal cord with fluorescently labeled CFA (cyan) and RFA (magenta) axons. Neurotrace is in gray. Major spinal laminae are demarcated (representative of N = 6 mice for C and D).

(E) Strategy to simultaneously label spinal neurons that are innervated by CFA or RFA.

(F) z stack projection of aligned photomicrographs of the cervical spinal cord. CFA_SC is in cyan and RFA_SC is in magenta (representative of N = 4 mice for [F] and [G]).

(G) Rotated 3D reconstruction of a section of the cervical spinal cord.

(H) Contour plot of CFA_SC labeling. D-V, dorsoventral; M-L, mediolateral (N = 4 mice for [H]–[M]).

(I) Contour plot of RFA_SC labeling.

(J) Contour plot of double-labeled neurons (CFA/RFA_SC neurons).

(K) Mean centroid positions of CFA_SC, RFA_SC, and CFA/RFA_SC populations.

(L) The major spinal cord structures containing CFA_SC and RFA_SC neurons. Regions colored red indicate a significant difference between CFA_SC and RFA_SC fractions. The inset is a photomicrograph with major spinal structures indicated.

(M) The spinal cord laminae and nuclei containing CFA_SC and RFA_SC neurons. The inset is a photomicrograph with spinal structures indicated.

Refer to Table S1 for a complete list of the spinal cord structures and their corresponding acronyms. Data are represented as mean ± SEM. Red text in (F) and (M): p < 0.05, **p < 0.01

See also Figure S1.