In a University
of California, a research team reports that in mouse models, the brain
significantly changed its visual cortex operation modes by implementing
top-down processes during learning. They found that when the mouse assigns a
new meaning to a previously neutral visual stimulus, top-down control becomes
much more influential in activating the visual cortex. Top-down inputs interact with specific neuron
types in the visual cortex to modulate its operation modes. This cognitive
process uses our thoughts and influences our senses. For example, when we see a
word with missing letters, our brain is able to fill in the blank based on past
experiences.
Researchers
looked at activity in excitatory neurons and somatostatin-expressing inhibitory
neurons in the visual cortex and top-down inputs from the retrosplenial cortex
(RSC) during associative learning to see how these affected the top-down and
bottom-up processing—when perception begins with the senses. The findings
indicate that intricate interactions of various circuit components effectively
change the balance of top-down and bottom-up processing, with learning
enhancing the contribution of top-down control. These results support the
long-standing theory that the brain does not faithfully represent the
environment but rather attempts to predict it based upon prior information.
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