Scientists uncover how decisions about what we see are relayed back
through the brain
Study in monkeys finds that in visual decision-making, information
relevant to the decision is broadcast widely

Date:
July 27, 2021
Source:
NIH/National Eye Institute
Summary:
Researchers have discovered that decisions based on visual
information, which involve a complex stream of data flowing forward
and backwards along the brain's visual pathways, is broadcast
widely to neurons in the visual system, including to those that
are not being used to make the decision.



FULL STORY ========================================================================== Researchers at the National Institutes of Health have discovered that
decisions based on visual information, which involve a complex stream of
data flowing forward and backwards along the brain's visual pathways, is broadcast widely to neurons in the visual system, including to those that
are not being used to make the decision. Feedback -- such as information
about a decision traveling back to neurons detecting visual features
like color or shape -- is thought to help the brain focus on visual
information that is relevant to decision-making.

The study, by scientists at the National Eye Institute (NEI), was
published in Nature Communications.


==========================================================================
"Why and how decision-making information is relayed back into the visual processing parts of the brain is an open question. Some theories posit
that this type of feedback should be selective -- only affecting those
neurons that are involved in the decision," said Hendrikje Nienborg,
Ph.D., chief of the NEI Unit on Visual Decision Making and lead author of
the study. "This study shows that decision-related feedback is spatially unselective, affecting neurons much more broadly than one might suppose." Feedback is used by the brain in many ways and many systems. When a
decision is based on what we see, information about expectation or
attention -- such as where the object is, or about its features -- is
fed back to brain regions involved in the visual process, raising the
activity of neurons involved in seeing the object or event in question.

An example of this type of expectation might be keeping an eye out for a pedestrian at a crosswalk while driving through an intersection. Neurons specialized in detecting objects to your right might receive an extra bit
of signal due to your attention. If you were trying to decide whether the person was your red jacket-clad child, neurons specializing in detecting
the color red might receive feedback.

Researchers have hypothesized that feedback may help the brain focus in
on hard-to-see features, or perhaps help stabilize the decision as it's
being made. Some scientists have thought that decision-related feedback
is selective, raising the activity of only the neurons involved in the decision, and not irrelevant neurons.

However, scientists wondered what happens when two different types
of information are relevant to a decision at the same time. Is there
feedback for each type of information, and is that feedback selective
for the decision? To answer this question, Katrina Quinn, a graduate
student in Nienborg's lab and first author of the study, and colleagues
trained monkeys to distinguish whether an object on a screen in a
particular location looked concave or convex, while ignoring objects
in irrelevant locations. While the animals were performing the task,
the researchers recorded the activity of neurons involved in processing
visual information. The animals were good at the task, efficiently distinguishing objects in the correct locations and ignoring objects in irrelevant locations.

To see whether the decision-related feedback was selective for both pieces
of relevant information, such as location and depth, the researchers
recorded activity from neurons that detect depth information and spatial location in the visual cortex, the part of the brain that specializes
in visual processing.

Despite the animals' stellar performance, the researchers discovered an unexpectedly nuanced picture of feedback in the visual system. Similar
to previous studies, they found that location feedback is selective,
but location feedback didn't vary depending on the decision the animal
made, it was only associated the location that the animal was paying
attention to. Conversely, feedback related to the object's depth was
associated with the decision, but was spatially unselective, meaning
that even depth-sensing neurons that couldn't possibly be used to make
the decision got extra decision-related feedback anyway.

"You would think that this kind of feedback is always tailored to the
task at hand, but it turns out we can't make that assumption," said Quinn.

"This study may point towards a feedback mechanism that generalizes across tasks, but in some ways, these findings raise more questions than they
answer," said Nienborg.

The study was funded by the NEI Intramural program, the European
Research Council, the German Research Foundation, and the National
Science Foundation.

========================================================================== Story Source: Materials provided by NIH/National_Eye_Institute. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Katrina R. Quinn, Lenka Seillier, Daniel A. Butts, Hendrikje
Nienborg.

Decision-related feedback in visual cortex lacks spatial
selectivity.

Nature Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-24629-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210727145239.htm

--- up 11 weeks, 4 days, 22 hours, 45 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)