An Ancient Pathway That Relays Visual Information in the Mammalian Brain
Have you ever jumped in fear, and then a split second later realized that a spider (or a spider-shaped shadow) was at the edge of your vision?
Your brain enables different kinds of responses to visual information. There’s the conscious response to what you see, which is what allows you to read and understand words, check the weather through a window, follow a complicated movie. But you can also respond subconsciously to the visual world through instinctive reactions like jumping away from something scary.
There are two interconnected sections of the brain thought to play a role in those instinctive responses: A small section of the brainstem, known as the superior colliculus, and the pulvinar, which is part of the thalamus and is nestled deep in the middle of the brain. These two structures, which both predate the evolution of mammals, have been implicated in intuitive responses to vision, but it was unclear how the pulvinar was responding to visual information.
Now, a new study of the mouse visual system led by Allen Institute researchers has shown that certain visual information passes from the eyes through these parts of the brain in mammals, rather than through the canonical neural pathway previously thought to be responsible for trafficking everything we see. The study, which was published Tuesday in the journal Neuron, relied on recordings of electrical activity from more than 1,500 neurons in the mouse brain using a newly developed type of silicon probe, Neuropixels.