Neuroscientists show mice can learn to manipulate random dopamine pulses for reward
From the thrill of hearing an ice cream truck approaching to peaks of pleasure while sipping on fine wine, the neurological messenger known as dopamine has been commonly described as the brain chemical “feeling good” linked 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 studied extensively from the point of view of external cues, or “deterministic” signals. Instead, researchers at the University of California at San Diego recently set out to study less understood aspects related to spontaneous dopamine impulses. Their results, published on July 23 in the journal Current biology, have shown that mice can voluntarily manipulate these random dopamine pulses.
Rather than only happening when presented with pleasurable or reward-based expectations, UC San Diego graduate student Conrad Foo conducted research that found the neocortex in mice is inundated with unpredictable pulses of dopamine that occur about once a minute.
Working with colleagues at UC San Diego (Department of Physics and Section of Neurobiology) and Icahn School of Medicine at Mount Sinai in New York City, Foo investigated whether mice are in fact aware that these impulses – documented in the laboratory by molecular and optical imaging techniques – actually happen. The researchers devised a feedback system in which mice on a treadmill received a reward if they showed they were able to control impromptu dopamine signals. Not only were the mice aware of these dopamine pulses, the data revealed, but the results confirmed that they had learned to anticipate and intentionally act on some of them.
“Critically, the mice learned to reliably elicit impulses (dopamines) before receiving a reward,” the researchers note in the article. “These effects reversed when the reward was suppressed. We speculate that spontaneous dopamine impulses may serve as a salient cognitive event in behavioral planning.”
The researchers say the study opens up a new dimension in the study of dopamine and brain dynamics. They now intend to expand this research to explore whether and how unpredictable dopaminergic events result in foraging, which is an essential aspect of foraging, mate search, and as social behavior. in the colonization of new home bases.
“We further speculate that an animal’s sense of spontaneous dopamine impulses may motivate it to seek and feed in the absence of known predictive reward stimuli,” the researchers noted.
In their efforts to control dopamine, the researchers clarified that dopamine appears to invigorate, rather than initiate, motor behavior.
“It started as a chance discovery by a talented and curious graduate student with the intellectual support of a wonderful group of colleagues,” said study co-lead author David Kleinfeld, professor in the Department of Physics (Division of Physical Sciences) and Section of Neurobiology (Division of Biological Sciences). “As an unforeseen outcome, we spent long days developing the original study and, of course, performing control experiments to verify the claims. This led to the current conclusions.”
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Material provided by University of California – San Diego. Original written by Mario Aguilera. Note: Content can be changed for style and length.