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. 2021 Jun 28;12:4004. doi: 10.1038/s41467-021-24241-2

Fig. 2. Visual, auditory, and somatic sensorimotor map of cortical projections to SC zones.

Fig. 2

a Color-coded schematic overview of the left visual field and body part topography based on their target zones in right hemisphere of SC at level 90. Reconstructions of cortico-tectal fibers adjacent. b Schematic of injection strategy using triple or double anterograde tracers into cortex, and custom SC atlas levels. c VISp, VISal, and PTLp-lat projections to SC.m and SC.cm. SC boundaries in all panels were delineated based on Nissl-stained cytoarchitecture. Dashed lines correspond to specific layers in each SC level. Scale bar 200 µm in SC panels. d Two neighboring caudal MOs regions and a rostral MOp injection send projections to adjacent, but nonoverlapping zones in the SC.cl and SC.l. e Rostral MOs and rostral-ventral MOp projections to the SC.l zone. f SSp-tr and AUDp projections target caudal SC.l zones. g Stacked bar chart for visualization of proportion of labeling across each SC zone (x-axis) from each cortical ROI (y-axis) for each selected ROI (n = 20 cases). Values represent proportion of pixel density for an individual ROI across each zone (n = 1 case per row). See Supplementary Table 3 for zone- and layer-specific values. h Probability distribution graphs of thresholded labeling represented by probability density (y-axis) across angular ranges (θ°) in SC (x-axis) from atlas level 90. VISam cases show distributions in angular ranges that align with SC.m and SC.cm zones (n = 3). MOs cases show distributions aligned with SC.cl (n = 10). SSp-ul cases show distributions in angular ranges aligned with SC.l (and SC.cl) zones (n = 3). Color-code associations: red (SC.m), orange (SC.cm), green (SC.cl), purple (SC.l). ACAd anterior cingulate cortex dorsal part, ARA Allen reference atlas, AAV Adeno-associated virus, AAV-gfp AAV green fluorescent protein, AAV-rfp AAV red fluorescent protein, MOp primary motor cortex, MOs secondary motor cortex, PHAL Phaseolus vulgaris leucoagglutinin, PTLp posterior parietal cortex, VISam visual cortex anterior medial part, SC superior colliculus, SC Layers: zo zonal, sg superficial gray, op optic, ig intermediate gray, iw intermediate white, dg deep gray, dw deep white, Somatotopic body parts; bfd barrel field, ll lower limb, m mouth, n nose, tr trunk, ul upper limb, SSp primary somatosensory cortex, VIS visual cortex. Complete list of abbreviations in Supplementary Table 1.