“…Retinotopic map formation in SC occurs during the first postnatal week in mice, involving both genetic and activity-dependent factors (Cang and Feldheim, 2013; Arroyo and Feller, 2016). These factors also play a key role in the development of a fine-scale organization in other sensory systems, such as the tonotopic map in the cochlear nucleus (Krasewicz and Yu, 2023), and the chemotopic map in the olfactory bulb where olfactory sensory neurons expressing the same olfactory receptor type project exclusively to the same single glomerulus (Imai et al, 2010). While overall sensory map formation is genetically predetermined by molecular cues (e.g., ephrin-Eph signaling; Frisén et al, 1998; Krasewicz and Yu, 2023; and axon-axon interactions; Plas et al, 2005; Cioni et al, 2018), a precise topography is established only after refinement that involves spontaneous activity, such as retinal waves during development (Chandrasekaran et al, 2005; Arroyo and Feller, 2016), and eventually experience-driven alignment (McLaughlin et al, 2003).…”