Nav: Home

Study identifies brain cells involved in Pavlovian response

March 22, 2017

In his famous experiment, Russian scientist Ivan Pavlov rang a bell each time he fed his dogs. Soon, the dogs began drooling in anticipation when they heard the bell, even before food appeared.

Now, a UCLA study has traced the Pavlovian response to a small cluster of brain cells -- the same neurons that go awry during Huntington's disease, Parkinson's disease and Tourette's syndrome. Published March 22 in the journal Neuron, the research could one day help neuroscientists find new approaches to diagnosing and treating these disorders.

"Species survive because they've learned how to link sensory cues like specific sounds, smells and sights to rewards like food and water," said Sotiris Masmanidis, the study's senior author and an assistant professor of neurobiology at the David Geffen School of Medicine at UCLA. "We wanted to uncover the brain circuitry that encodes reward-based learning and behavior."

The UCLA team focused on cellular activity in the striatum, a part of the brain associated with reward, movement and decision-making.

In a modern version of Pavlov's experiment, Masmanidis and colleagues repeatedly exposed mice to the unfamiliar scent of banana or lemon, followed by a drop of condensed milk. Eventually, the mice learned that the fragrances predicted the arrival of a sweet reward and began fervently licking the air in anticipation.


"The mice learned to associate the new scent with food, just like Pavlov's dogs," said Masmanidis, who is also a member of UCLA's California NanoSystems Institute and Brain Research Institute. "Our next step was to uncover what happens to the Pavlovian response when we silence different groups of cells in the striatum."

Based on clues from earlier studies, the team zeroed in on a tiny group of cells that support the principal neurons in the striatum. Although these supporting players comprise fewer than 2 percent of the cells in the region, the scientists were surprised to discover that they play a disproportionately important role.

"When we switched off the support cells, the mice licked the air in anticipation of the milk only half as often as normal," Masmanidis said. "We suspect that the support cells enhance the brain circuits that encode Pavlovian response."

The support cells' influence appeared strongest when the mice were first learning to pair the unfamiliar scents with a reward. The change was less dramatic in mice who had already mastered the connection.

"These cells were most essential to inexperienced mice who hadn't yet mastered the Pavlovian response," Masmanidis said.

The findings suggest that malfunctioning support cells could lead to neurological disorders, and that restoring the cells' function could eventually help people with these diseases.

More than a century after Pavlov's classic study, there is still much to learn about Pavlovian responses. "Our findings open up exciting opportunities for further studying the roles of different types of neurons in health and disease," said joint first-author Kwang Lee, a UCLA postdoctoral researcher in neurobiology.
The paper's other co-authors are joint first-author Sandra Holley, Justin Shobe, Natalie Chong, Carlos Cepeda and Michael Levine, all of UCLA.

The study was funded by the McKnight Endowment Fund for Neuroscience, the National Institute on Drug Abuse, the National Institute of Neurological Diseases and Stroke, and the National Science Foundation.

University of California - Los Angeles Health Sciences

Related Neurons Articles:

New tool to identify and control neurons
One of the big challenges in the Neuroscience field is to understand how connections and communications trigger our behavior.
Neurons that regenerate, neurons that die
In a new study published in Neuron, investigators report on a transcription factor that they have found that can help certain neurons regenerate, while simultaneously killing others.
How neurons use crowdsourcing to make decisions
When many individual neurons collect data, how do they reach a unanimous decision?
Neurons can learn temporal patterns
Individual neurons can learn not only single responses to a particular signal, but also a series of reactions at precisely timed intervals.
A turbo engine for tracing neurons
Putting a turbo engine into an old car gives it an entirely new life -- suddenly it can go further, faster.
Brain neurons help keep track of time
Turning the theory of how the human brain perceives time on its head, a novel analysis in mice reveals that dopamine neuron activity plays a key role in judgment of time, slowing down the internal clock.
During infancy, neurons are still finding their places
Researchers have identified a large population of previously unrecognized young neurons that migrate in the human brain during the first few months of life, contributing to the expansion of the frontal lobe, a region important for social behavior and executive function.
How many types of neurons are there in the brain?
For decades, scientists have struggled to develop a comprehensive census of cell types in the brain.
Molecular body guards for neurons
In the brain, patterns of neural activity are perfectly balanced.
Engineering researchers use laser to 'weld' neurons
University of Alberta researchers have developed a method of connecting neurons, using ultrashort laser pulses -- a breakthrough technique that opens the door to new medical research and treatment opportunities.

Related Neurons Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...