241 — The functional organization of cortical feedback inputs to primary visual cortex
Using calcium imaging from GCaMP6-expressing AAV infection across LM, this team looked at cortical feedback inputs transmitted to mouse V1. V1 is conventionally considered to be retinotopically arranged (the organization follows the part of the retina receiving an upstream visual field input). Though V1 was largely retinotopic, the researchers also noticed that some axons relayed distal visual signals, which complicates the otherwise 1-to-1 mapping scheme.
The preservation of retinotopy in neighboring visual regions is expected — but the researchers also found higher resolution data (using scanning-bar stimuli) that demonstrated that the distribution of inputs to orientation-selective regions of visual cortex “fuzz” perpendicular to the preferred orientation. In other words, if a region prefers 90º stimuli, its inputs are most likely distributed along the 0º axis.
The authors bring up the question of cross-species preservation of this (and other) organization conclusions: If we draw these sorts of conclusions on mice, how conserved are these patterns in primates? Or, for that matter, in other mammals, or even other vertebrates?