(A) Sensations drive adaptive behaviors via pathways from peripheral sensory neurons to the NMJ. (B) Projection pattern of functionally distinct RGC subtypes. dLGN, dorsal lateral geniculate nucleus; IGL, intergeniculate nucleus; vLGN, ventral lateral geniculate nucleus; mdPPN, medial division of the posterior pretectal nucleus; MTN, medial terminal nucleus; NOT, nucleus of the optic tract; OPN, olivary pretectal nucleus; SC, superior colliculus. (C) Normal RGC targeting of pretectum. (D–E) Potential outcomes of losing luminance-sensing RGC input. (F) Schematic of PLR circuit. CG, ciliary ganglion; EW, Edinger-Westphal nucleus; OPN, olivary pretectal nucleus. (G) Role of pupil constriction.