Surprise discovery reveals second visual system in mouse cerebral cortex

The visual system is probably the best-understood part of the brain. Over the past 75 years, neuroscientists have assembled a detailed account of how light waves entering your eyes allow you to recognize your grandmother's face, to track a hawk in flight, or to read this sentence. But a new study by UC San Francisco researchers is calling a fundamental aspect of vision science into question, showing that even the best-studied parts of the brain can still hold plenty of surprises.
According to the standard model of visual processing, all visual information from the retina must first pass through the primary visual cortex (V1) in the back of the brain, which extracts simple features like lines and edges, before being distributed to a number of "higher order" visual areas that extract increasingly complex features like shapes, shading, movement, and so on.
The new study—published online January 4, 2019, in Science—shows for the first time that one of these supposedly higher-order visual areas, which is involved in the perception of moving objects, does not depend on information from V1 at all. Instead, this region, known as the post-rhinal cortex (POR), appears to obtain visual data directly from an evolutionarily ancient sensory processing center at the base of the brain called the superior colliculus.