Tiny worms make complex decisions, too
Scientists surprised to discover flexible decision-making capabilities in
a worm with just 302 neurons
Date:
March 7, 2022
Source:
Salk Institute
Summary:
How does an animal make decisions? Scientists have spent decades
trying to answer this question by focusing on the cells and
connections of the brain that might be involved. Scientists are
taking a different approach -- analyzing behavior, not neurons. They
were surprised to find that worms can take multiple factors into
account and choose between two different actions, despite having
only 302 neurons compared to approximately 86 billion in humans.
FULL STORY ==========================================================================
How does an animal make decisions? Scientists have spent decades trying to answer this question by focusing on the cells and connections of the brain
that might be involved. Salk scientists are taking a different approach -- analyzing behavior, not neurons. They were surprised to find that worms
can take multiple factors into account and choose between two different actions, despite having only 302 neurons compared to approximately 86
billion in humans.
==========================================================================
The findings, published in Current Biology on March 7, 2022, have
important implications for the way researchers assess motivation and
cognitive abilities in animals. What's more, the study demonstrates that complex decision-making capabilities could be encoded in small biological
and artificial networks.
"Our study shows you can use a simple system such as the worm to
study something complex, like goal-directed decision-making. We also demonstrated that behavior can tell us a lot about how the brain works,"
says senior author Sreekanth Chalasani, associate professor in Salk's
Molecular Neurobiology Laboratory. "Even simple systems like worms
have different strategies, and they can choose between those strategies, deciding which one works well for them in a given situation. That provides
a framework for understanding how these decisions are made in more complex systems, such as humans." Whether eating prey or defending its food
source, the predatory worm Pristionchus pacificus relies on biting. The
team's challenge was to determine the worm's intentions when it bites.
The researchers found that P. pacificus chooses between two
foraging strategies for biting its prey and competitor, another
worm called Caenorhabditis elegans: 1) predatory strategy, in which
its goal for biting is to kill prey, or 2) territorial strategy, in
which biting is instead used to force C. elegans away from a food
source. P. pacificuschooses the predatory strategy against larval
C. elegans, which is easy to kill. In contrast, P. pacificus selects
the territorial strategy against adult C. elegans, which is difficult
to kill and outcompetes P. pacificus for food.
To the team, it appeared that P. pacificusweighed the costs and benefits
of multiple potential outcomes of an action -- behavior that's familiar
in vertebrates but unexpected in a worm.
"Scientists have always assumed that worms were simple -- when
P. pacificus bites we thought that was always for a singular predatory purpose," says first author Kathleen Quach, a postdoctoral fellow in Chalasani's lab. "Actually, P.
pacificus is versatile and can use the same action, biting C. elegans,
to achieve different long-term goals. I was surprised to find that P.
pacificuscould leverage what seemed like failed predation into successful
and goal-directed territoriality." In the future, the scientists would
like to determine which of P. pacificus' cost-benefit calculations are hard-wired or flexible. They hope more research like this will help
further uncover the molecular underpinnings of decision- making.
The research was supported by the National Institutes of Health
(5R01MH113905), the W.M. Keck Foundation, the National Science Foundation,
Salk Women & Science and a Paul F. Glenn Foundation Postdoctoral
Fellowship.
========================================================================== Story Source: Materials provided by Salk_Institute. Note: Content may
be edited for style and length.
========================================================================== Related Multimedia:
* C._elegans_worm_escaping_the_predatory_P._pacificus_worm ========================================================================== Journal Reference:
1. Kathleen T. Quach, Sreekanth H. Chalasani. Flexible reprogramming of
Pristionchus pacificus motivation for attacking Caenorhabditis
elegans in predator-prey competition. Current Biology, 2022; DOI:
10.1016/ j.cub.2022.02.033 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220307113024.htm
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