Every time I heard that the vertebrate retina does not receive any feedback from the central brain I expressed scepticism, and was told repeatedly that no, feedback fibers running backwards along the optic nerve were never found.
Now*, Sylvia Schröder et al. reports that:
"Arousal modulates retinal output", Schröder et al. 2020 https://www.cell.com/neuron/fulltext/S0896-6273(20)30318-4
Recordings with neuropixels probes on the optic tract of the mouse showed changes in retinal ganglion cell (RGC) activity (the output neurons of the retina whose axons make up the optical tract) in concordance with the arousal state of the mouse. They also measured activity of RGC axon boutons in the superior colliculus.
What a fantastic piece of work.
* for long values of "now".
Also it's "now" more clear that these effects are histamine-mediated.
Some more awesome work by the Rivlin lab: https://www.science.org/doi/10.1126/sciadv.adk4062
