Figure 8. Circuits controlling innate visual responses in the mouse.

(A) Projections of the crossed pathway, principally from the dSC to the contralateral PMRF (green), drive orienting movements. In addition to the PMRF, descending collaterals are projected to the contralateral dSC (co-dSC), the precerebellar nuclei such as the nucleus reticularis tegmenti pontis (NRTP) and inferior olive (IO), the raphe, and further down to the spinal cord (Spc). In addition, collaterals are also projected ipsilaterally to the pedunculopontine tegmental nucleus (PPN) and partly to the PRMF in the pons, mesencephalic reticular formation (mRt) and substantia nigra pars compacta (SNc) in the midbrain. Furthermore, ascending axons are projected to several thalamic and midbrain nuclei on the ipsilateral side, some of which might function an efference copy signal. (B) Projections forming the uncrossed pathway (magenta), from the dSC to the ipsilateral cuneiform nucleus (CnF), control evasive movements. Here, collaterals of the descending branch are projected to the PPN, inferior colliculus (IC), PMRF, raphe and IO. In the midbrain, collaterals are projected to the dorsal periaqueductal gray matter (dPAG), SNc and mRt, some of which might be related to the emotional and reward-related aspects of the behavior. Furthermore, ascending axons are projected to several thalamic and midbrain nuclei on the ipsilateral side. Adapted from Dean et al, 1989 ⁵; Sahibzada et al, 1986 ⁶ and Isa et al, 2020 ²⁰⁸.