Figure 1.

Glutamatergic MLR neurons segregate by projection target

(A) Strategy for retrograde labeling of glutamatergic MLR neurons from substantia nigra (SN), spinal cord (SC), and medulla (Med).

(B) Average number (±SEM) of labeled cells along the rostro-caudal axis (n = 9).

(C) Cell density from an example animal at bregma −4.84 mm containing PPN, mRT, and CnF subdivisions.

(D) Left: two-dimensional reconstruction of MLR neurons projecting to Med, SC, or SN at bregma −4.84 mm (n = 3). Right: quantification of labeled cell number in MLR subregions for each subpopulation (n = 9). Error bars represent SEM.

(E) Average number (±SEM) of labeled cells for the three retrograde injections in PPN, mRT, and (p)CnF along its rostro-caudal axis (n = 9).

(F) Pairwise comparison of the cellular overlap between MLR subpopulations. Two-dimensional distribution of single or double (orange) labeled cells at bregma −4.84 mm (left) and total percentage of overlapping cells for each subpopulation pair shown in Venn diagrams (right; n = 6 per pair). Percentage of double-labeled neurons (mean ± SEM) were Med+SC/SC, 81.3% ± 2.7%; Med+SC/Med, 10.1% ± 1.1%; Med+SN/SN, 8.8% ± 2.4%; Med+SN/Med, 2.7% ± 0.8%; SN+SC/SN, 2.8% ± 0.9%; SN+SC/SC, 3.1% ± 0.8%.

See also Figure S1.