Only neurons responding within the visually matching segments are included (2992/4602). ( d) Cumulative distribution of the spatial modulation index (SMI) for the V1 neurons. The ordering was based on separate data (odd-numbered trials). ( c) Responses of 4602 V1 neurons (out of 16,238) whose activity was modulated along the corridor (≥5% explained variance), ordered by the position of their peak response. Dotted lines are predictions assuming identical responses in the two segments. The corridor had two landmarks that repeated after 40 cm, creating visually matching segments ( top). ( b) Normalized responses of three example V1 neurons, as a function of position in the virtual corridor. ( a) Example retinotopic map ( colors) showing borders between visual areas ( contours) and imaging sessions targeting V1 fully or partly ( squares, field of view: 500 × 500 µm). If spatial modulation signals reach visual cortex from the navigational system, therefore, they should grow with active navigation and with experience of the environment. In addition, both hippocampal place fields and entorhinal grid patterns grow stronger when an environment becomes familiar ( Barry et al., 2012 Frank et al., 2004 Karlsson and Frank, 2008). In the navigational system, spatial encoding is stronger in active navigation than during passive viewing, when most hippocampal place cells lose their place fields ( Chen et al., 2013 Song et al., 2005 Terrazas et al., 2005). Moreover, it is not known if the spatial modulation of visual responses varies with experience in the environment or active navigation. For instance, they might be stronger in parietal areas such as A and AM ( Hovde et al., 2018), because many neurons in parietal cortex are associated with spatial coding ( Krumin et al., 2018 McNaughton et al., 1994 Nitz, 2006 Save and Poucet, 2009 Whitlock et al., 2012 Wilber et al., 2014). Spatial signals might also become stronger downstream of V1, in higher visual areas (HVAs). Indeed, spatial signals have been seen elsewhere in thalamus ( Jankowski et al., 2015 Taube, 1995) and possibly also in LGN itself ( Hok et al., 2018). Spatial signals might enter the visual pathway upstream of V1, in the lateral geniculate nucleus (LGN). It is not known, however, how this spatial modulation varies along the visual pathway. The underlying spatial signals covary with those in hippocampus and are affected similarly by idiothetic cues ( Fournier et al., 2020 Saleem et al., 2018). During navigation, indeed, the visual responses of V1 neurons are modulated by the animal’s estimate of spatial position ( Saleem et al., 2018). There is increasing evidence that the activity of the mouse primary visual cortex (V1) is influenced by navigational signals ( Fiser et al., 2016 Flossmann and Rochefort, 2021 Fournier et al., 2020 Haggerty and Ji, 2015 Ji and Wilson, 2007 Pakan et al., 2018 Saleem et al., 2018).