Mammalian motivation circuits: Maybe they're born with it

Date:
October 18, 2021
Source:
Cold Spring Harbor Laboratory
Summary:
Are animals born to seek rewards or avoid punishment? Researchers
found that mice have pre-programmed neurons and circuits that
process 'positive' and 'negative' stimuli. Their findings may
be useful for studying neurological and psychiatric disorders
in humans.



FULL STORY ==========================================================================
Are we born to fear punishment or crave rewards? Or do those capacities
evolve with experience? Cold Spring Harbor Laboratory (CSHL) Professor
Bo Li and his lab found that mice have pre-programmed circuits that
process "positive" and "negative" stimuli. These neurons are found in
the mouse's amygdala, a section of the brain that deals with learning
rewards and punishments. The researchers' findings may be useful for
studying neurological and psychiatric disorders in humans.


========================================================================== Previously, Li and his colleagues discovered that the amygdala is the
hub for both fear- and reward-based learning. Xian Zhang, a postdoc in
Li's lab, wanted to find out the exact circuitry that takes in positive
or negative stimuli that trigger either pleasure or fear.

In an experiment similar to how Pavlov's dog was taught to associate
a bell sound with food, Li and Zhang trained mice to connect certain
sounds with either a reward (a refreshing drink of water) or a punishment
(an annoying puff of air to the whiskers). Then, in collaboration with
CSHL Adjunct Professor Z.

Josh Huang, they developed a method to mark and observe different neurons
in the mouse amygdala. They discovered two distinct types of neurons:
one that was activated when the mouse heard the reward sound, and one
that was activated when it heard the punishment sound. Both neuron
populations exist throughout the entire amygdala. Li explains: "They're spatially intermingled. When you start to image them, you know that some
of the neurons respond only to good things, some of the neurons respond
only to bad things, just like the pepper and the salt mixed together,
and they do different jobs." The researchers were surprised to discover
that some amygdala cells are hardwired to process motivation stimuli,
even without training. A puff of air or sip of water triggered the same
neurons in both untrained and trained mice.

Zhang thinks their findings may be relevant to human psychiatric disorders
like depression. He says: "If you have an imbalanced bit in different
neural circuits, you probably have a deficit of your motivation, like
you lost your interest in pursuing rewards, or you lost your interest
in avoiding punishment. I think this finding is important to know for
the future, to help people with depression or other mental disorders."
In mouse models of depression, animals lack the motivation to seek rewards
or avoid punishments. Li and Zhang hope that this study, published in
Nature Neuroscience, will help researchers understand how motivation
works or goes wrong in mammalian brains.

========================================================================== Story Source: Materials provided by
Cold_Spring_Harbor_Laboratory. Original written by Jasmine Lee. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Zhang, X., Guan, W., Yang, T. et al. Genetically identified
amygdala-
striatal circuits for valence-specific behaviors. Nature
Neuroscience, 2021 DOI: 10.1038/s41593-021-00927-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211018112453.htm

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