Abstract
Multiple sources innervate the visual thalamus to influence image-forming vision prior to the cortex, yet coordination between non-retinal and retinal inputs in shaping thalamic visual selectivity remains unclear. Using dual-color two-photon calcium imaging in the thalamus of awake mice, we observed a higher fraction of direction-selective boutons among input from superior colliculus neurons than from retinal ganglion cells, both providing strong converging excitatory input to thalamic neurons. Collicular and retinal axons exhibit retinotopic organization with similar precision. At a fine scale of ∼10 μm, collicular boutons often shared feature preferences with nearby retinal boutons. Inhibiting collicular input significantly suppressed visual responses in thalamic shell neurons and specifically reduced selectivity in neurons preferring motion along the temporal direction or horizontal axis. These findings suggest that the thalamus is not merely a relay but selectively integrates inputs from multiple regions to build stimulus selectivity and shape the information transmitted to the cortex.
Keywords:
chronic two-photon calcium imaging in awake mice; colliculogeniculate axons; dorsal lateral geniculate nucleus; functional convergence; motion selectivity; presynaptic functional clustering; retinogeniculate axons; superior colliculus; visual processing; visual thalamus.