Scientists solve long-standing mystery by a whisker

January 29, 2021

RIVERSIDE, Calif. -- When we step on the car brake upon seeing a red traffic light ahead, a sequence of events unfolds in the brain at lightning speed.

The image of the traffic light is transferred from our eyes to the visual cortex, which, in turn, communicates to the premotor cortex -- a section of the brain involved in preparing and executing limb movements. A signal is then sent to our foot to step on the brake. However, brain region that helps the body go from "seeing" to "stepping" is still a mystery, frustrating neuroscientists and psychologists.

To unpack this "black box," a team of neuroscientists at the University of California, Riverside, has experimented on mice to identify the brain region that functions beyond sensory encoding and motor encoding, potentially opening up new directions to studying the cellular and circuit mechanisms of sensory-motor transformations. The researchers report a cortical region traditionally defined as whisker motor cortex in mice is most directly related to the transformation process.

In the lab, the researchers trained mice to sense a slight deflection on one side of their whiskers, and report if they sensed it by licking a water port.

"We recorded the neuronal activity of some brain regions that might convey this sensory-motor transformation by using the 'language of neurons' -- the electrical signals -- generated as the mouse performs the task of stimulus detection," said Zhaoran Zhang, a graduate student in the Neuroscience Graduate Program and a co-first author of the research paper published in eNeuro, an open-access journal of the Society of Neuroscience.

Behzad Zareian, a graduate student in the Department of Psychology and a co-first author of the research paper, explained the team used simple but intuitive mathematical tools to transform the neurons' electrical activities to numbers that describe how much the neurons sense the sensory input, how much they reflect the upcoming movement outputs, and how well they predict whether the sensory information can be successfully transformed to a correct behavior.

"We located a brain region traditionally defined as the whisker motor cortex, which was previously believed to influence how a mouse moves its whiskers," Zareian said, "We found this cortical region is capable of transforming the sensory input from whisker deflection to a more general movement action -- licking in this case -- rather than just moving whiskers."

Corresponding author Edward Zagha, an assistant professor of psychology and the team's principle investigator, explained that one difficulty in finding brain regions operating the sensory-motor transformation is that although scientists can measure the sensory- and motor-related brain activities easily in the lab, the inner process that conducts the sensory-motor transformation in the brain is elusive and hard to quantify.

"Our brain represents sensory and motor information in more than one place and often in a redundant manner for multiple purposes such as fine-tuning future movements, enhancing perception or memory storage," Zagha said. "Thus, scientists are now able to distinguish the location of transformation and the regions that merely reflect the sensory or motor information for other purposes. This can vastly improve the use of targeted therapy for patients with sensory- and motor-related brain deficits."

Next, the team plans to focus its research on whisker motor cortex to show what happens within this region to enable the transformation process.

"Interestingly, each cortical region consists of multiple layers and multiple subtype of neurons such as excitatory and inhibitory neurons that are subject to research," Zagha said. "Thus, this expands our knowledge of the neurobiological circuits performing sensory-motor transformations and identifies sites of potential therapeutic intervention to modulate these brain functions."
-end-
The research was funded by grants from the Whitehall Foundation and National Institutes of Health.

The research paper is titled "Cortical Localization of the Sensory-Motor Transformation in a Whisker Detection Task in Mice."

The University of California, Riverside (http://www.ucr.edu) is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment is more than 25,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of almost $2 billion. To learn more, email news@ucr.edu.

University of California - Riverside

Related Brain Articles from Brightsurf:

Glioblastoma nanomedicine crosses into brain in mice, eradicates recurring brain cancer
A new synthetic protein nanoparticle capable of slipping past the nearly impermeable blood-brain barrier in mice could deliver cancer-killing drugs directly to malignant brain tumors, new research from the University of Michigan shows.

Children with asymptomatic brain bleeds as newborns show normal brain development at age 2
A study by UNC researchers finds that neurodevelopmental scores and gray matter volumes at age two years did not differ between children who had MRI-confirmed asymptomatic subdural hemorrhages when they were neonates, compared to children with no history of subdural hemorrhage.

New model of human brain 'conversations' could inform research on brain disease, cognition
A team of Indiana University neuroscientists has built a new model of human brain networks that sheds light on how the brain functions.

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.

Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.

An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.

Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.

Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.

Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.

Read More: Brain News and Brain Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.