'Feel good' brain messenger can be willfully controlled, new study
reveals
Neuroscientists show that mice can learn to manipulate random dopamine impulses for reward

Date:
July 23, 2021
Source:
University of California - San Diego
Summary:
Researchers have discovered that spontaneous impulses of dopamine,
the neurological messenger known as the brain's 'feel good'
chemical, occur in the brain of mice. The study found that mice
can willfully manipulate these random dopamine pulses for reward.



FULL STORY ========================================================================== [Dopamine molecule, brain | Credit: (c) Andrea Danti / stock.adobe.com] Dopamine molecule, brain illustration (stock image).

Credit: (c) Andrea Danti / stock.adobe.com [Dopamine molecule, brain |
Credit: (c) Andrea Danti / stock.adobe.com] Dopamine molecule, brain illustration (stock image).

Credit: (c) Andrea Danti / stock.adobe.com Close From the thrill of
hearing an ice cream truck approaching to the spikes of pleasure while
sipping a fine wine, the neurological messenger known as dopamine has
been popularly described as the brain's "feel good" chemical related to
reward and pleasure.


==========================================================================
A ubiquitous neurotransmitter that carries signals between brain cells, dopamine, among its many functions, is involved in multiple aspects
of cognitive processing. The chemical messenger has been extensively
studied from the perspective of external cues, or "deterministic"
signals. Instead, University of California San Diego researchers recently
set out to investigate less understood aspects related to spontaneous
impulses of dopamine. Their results, published July 23 in the journal
Current Biology, have shown that mice can willfully manipulate these
random dopamine pulses.

Rather than only occurring when presented with pleasurable, or
reward-based expectations, UC San Diego graduate student Conrad Foo
led research that found that the neocortex in mice is flooded with unpredictable impulses of dopamine that occur approximately once per
minute.

Working with colleagues at UC San Diego (Department of Physics and Section
of Neurobiology) and the Icahn School of Medicine at Mount Sinai in New
York, Foo investigated whether mice are in fact aware that these impulses
-- documented in the lab through molecular and optical imaging techniques
-- are actually occurring. The researchers devised a feedback scheme in
which mice on a treadmill received a reward if they showed they were able
to control the impromptu dopamine signals. Not only were mice aware of
these dopamine impulses, the data revealed, but the results confirmed that
they learned to anticipate and volitionally act upon a portion of them.

"Critically, mice learned to reliably elicit (dopamine) impulses prior
to receiving a reward," the researchers note in the paper. "These effects reversed when the reward was removed. We posit that spontaneous dopamine impulses may serve as a salient cognitive event in behavioral planning."
The researchers say the study opens a new dimension in the study of
dopamine and brain dynamics. They now intend to extend this research
to explore if and how unpredictable dopamine events drive foraging,
which is an essential aspect of seeking sustenance, finding a mate and
as a social behavior in colonizing new home bases.

"We further conjecture that an animal's sense of spontaneous dopamine
impulses may motivate it to search and forage in the absence of known reward-predictive stimuli," the researchers noted.

In their efforts to control dopamine, the researchers clarified that
dopamine appears to invigorate, rather than initiate, motor behavior.

"This started as a serendipitous finding by a talented, and curious,
graduate student with intellectual support from a wonderful group of colleagues," said study senior co-author David Kleinfeld, a professor
in the Department of Physics (Division of Physical Sciences) and Section
of Neurobiology (Division of Biological Sciences). "As an unanticipated
result, we spent many long days expanding on the original study and of
course performing control experiments to verify the claims. These led to
the current conclusions." The full authors list of the paper includes:
Conrad Foo, Adrian Lozada, Johnatan Aljadeff, Yulong Li, Jing W. Wang,
Paul A. Slesinger and David Kleinfeld.

The BRAIN Initiative at the National Institutes of Health (grants
DA050159, DC009597, MH111499, NS107466 and NS097265) supported the
research.

========================================================================== Story Source: Materials provided by
University_of_California_-_San_Diego. Original written by Mario
Aguilera. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Conrad Foo, Adrian Lozada, Johnatan Aljadeff, Yulong Li, Jing
W. Wang,
Paul A. Slesinger, David Kleinfeld. Reinforcement learning links
spontaneous cortical dopamine impulses to reward. Current Biology,
2021; DOI: 10.1016/j.cub.2021.06.069 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210723121512.htm

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