(July 13, 2015) From
the smell of flowers to the taste of wine, our perception is strongly
influenced by prior knowledge and expectations, a cognitive process known as
top-down control.
In a University of California, San Diego School of Medicine
study published July 13 in the online journal Nature Neuroscience, a research
team led by Takaki Komiyama, PhD, assistant professor of neurosciences and
neurobiology, reports that in mouse models, the brain significantly changed its
visual cortex operation modes by implementing top-down processes during
learning.
“We 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,” said first author Hiroshi Makino,
PhD, postdoctoral researcher in Komiyama’s lab. “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.