Thursday, November 27, 2025

Prefrontal cortex reaches back into the brain to shape how other regions function

A new MIT study illustrates how areas within the brain’s executive control center tailor their messages in specific circuits with other brain regions to influence them with information about behavior and internal feelings.

Picower Institute at MIT

Innervated cortex — image:
An image from the research shows axons from neurons in the ACA (red) and ORB (green) innervating the visual cortex, targeting discrete layers.
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Credit: Sur Lab/MIT Picower Institute

Vision shapes behavior and, a new study by MIT neuroscientists finds, behavior and internal states shape vision. The research, published Nov. 25 in Neuron, finds in mice that via specific circuits, the brain’s executive control center, the prefrontal cortex, sends tailored messages to regions governing vision and motion to ensure that their work is shaped by contexts such as the mouse’s level of arousal and whether they are on the move.

“That’s the major conclusion of this paper: There are targeted projections for targeted impact,” said senior author Mriganka Sur, Paul and Lilah Newton Professor in The Picower Institute for Learning and Memory and MIT’s Department of Brain and Cognitive Sciences.

Neuroscientists, including Sur’s office next-door neighbor at MIT Earl K. Miller, have long suggested that the prefrontal cortex biases the work of regions further back in the cortex. Tracing of anatomical circuits supports this idea. But in the new study, lead author and Sur Lab postdoc Sofie Ährlund-Richter sought to determine whether the PFC is broadcasting a generic signal or customizes the information it conveys for different downstream regions. She also wanted to take a fresh look at which neurons the PFC talks to, and what impact the information has on how those regions function.

Ährlund-Richter and Sur’s team uncovered several new revelations. One was that the two prefrontal areas they focused on, the orbitofrontal cortex (ORB) and the anterior cingulate area (ACA), selectively convey information about arousal and motion to the two downstream regions they studied, the primary visual cortex (VISp) and the primary motor cortex (MOp), to achieve distinct ends. For instance, the more aroused a mouse was the more ACA prompted VISp to sharpen the focus of visual information it represented, but ORB only chimed in if arousal was very high and then its input seemed to reduce the sharpness of visual encoding. Ährlund-Richter speculates that as arousal increases, ACA may help the visual cortex focus on resolving what might be salient in what it’s seeing, while ORB might be suppressing focus on unimportant distractors.

“These two PFC subregions are kind of balancing each other,” Ährlund-Richter said. “While one will enhance stimuli that might be more uncertain or more difficult to detect, the other one kind of dampens strong stimuli that might be irrelevant.”

Tracing and tapping circuits

In the study, Ährlund-Richter performed detailed anatomical tracings of the circuits that ACA and ORB forge with VISp and MOp to map their connections. In other experiments, mice were free to run on a wheel as they also watched both structured images or naturalistic movies at varying levels of contrast. Sometimes the mice received little air puffs that made them more aroused. Meanwhile, the neuroscientists tracked the activity of neurons in ACA, ORB, VISp and MOp. In particular, they eavesdropped on the information flowing through the neural projections (or “axons”) that extended from the prefrontal to the posterior regions.

The anatomical tracings showed that complementary some prior studies, the ACA and ORB each connect to many different types of cells in the target regions, not just one cell type. But they do so with distinct geographies. In VISp, for instance, ACA tapped in to layer 6 whereas ORB tapped into layer 5.

In their analysis of the transmitted information and neural activity, the scientists could discern several trends. ACA neurons conveyed more visual information than the ORB neurons and were more sensitive to changes in contrast. ACA neurons also scaled with arousal state, while ORB neurons seemed to only care if arousal crossed a high threshold. Meanwhile, when “talking” to MOp, the ACA and ORB each conveyed information about running speed, but with VISp, the regions only conveyed whether the mouse was moving or not. Finally, ACA and ORB also conveyed arousal state and a trickle of visual information to MOp.

To understand what effect this information flow had on visual function, the scientists sometimes blocked the circuits that ACA and ORB forged with VISp to see how that changed what VISp neurons did. That’s how they found that ACA and ORB affected visual encoding in specific and opposite ways, based on the mouse’s arousal level and movement.

“Our data support a model of PFC feedback that is specialized at both the level of PFC subregions and their targets, enabling each region to selectively shape target-specific cortical activity rather than modulating it globally,” the authors wrote in Neuron.

In addition to Sur and Ährlund-Richter, the paper’s other authors are Yuma Osako, Kyle R. Jenks, Emma Odom, Haoyang Huang, and Don B. Arnold.

Funding for the study came from a Wenner-Gren foundations Postdoctoral Fellowship, the National Institutes of Health, and the Freedom Together Foundation.

Journal

Neuron

DOI

10.1016/j.neuron.2025.10.037

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Distinct roles of prefrontal subregion feedback to the primary visual cortex across behavioral states

Article Publication Date

25-Nov-2025

New research from Montana State highlights subsurface impact of Yellowstone earthquakes

Montana State University

image:
Montana State University professor Eric Boyd pictured in the Norris Geyser Basin at Yellowstone National Park.
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Credit: MSU photo by Kelly Gorham.

BOZEMAN – In Yellowstone National Park, earthquakes are an everyday occurrence whether humans feel them or not. In fact, data shows that as many as 3,000 quakes of various magnitudes occur in the park each year.

That regularity makes Yellowstone a perfect place to study the many impacts of seismic activity on ecosystems, said Montana State University professor Eric Boyd. In a new paper published this week in the journal PNAS Nexus, Boyd explores how Yellowstone’s earthquakes impact some of the planet’s earliest lifeforms, and what such lifeforms could tell us about life on other planets.

“I think it's one of the more significant findings that I have ever been a part of,” said Boyd, who has conducted research in Yellowstone for more than two decades as part of MSU’s Department of Microbiology and Cell Biology. “There are hypotheses that microbial life originated in the subsurface 3.8 billion years ago. These microbes would have been dependent on chemical forms of energy stored in minerals. As the microbes consumed this energy, the minerals would become depleted, and there’s simply no way such ecosystems could persist without a mechanism to replenish them.”

By fracturing and shearing rock, earthquakes allow fresh, reactive minerals to be exposed, Boyd said. While earthquakes are common nearly everywhere, they are particularly frequent in a volcanically active place like Yellowstone, making it a perfect location for the research.

“Eric’s investigation into how seismic activity shapes microbial communities in the Yellowstone ecosystem is yet another excellent example of his groundbreaking research exploring how microbial life persists and evolves in extreme environments,” said Jovanka Voyich, head of the Department of Microbiology and Cell Biology, which is housed in MSU’s College of Agriculture. “The fact that MSU undergraduate and graduate students can take courses and receive mentorship from one of the world’s most prestigious geobiologists is a remarkable educational opportunity.”

Boyd is the lead author on the new paper, titled “Seismic Shifts in the Geochemical and Microbial Composition of a Yellowstone Aquifer.” The work brought together extensive data on the underground systems of the national park, including measurements of thousands of earthquakes and explorations of the microbes that live beneath the surface, along with the chemicals that they need to survive. Early Earth, Boyd said, didn’t have an atmosphere like the one it has today, so radiation levels on the surface would have made it uninhabitable. For that reason, early life most likely originated underground. But how did it survive there?

That question has driven much of Boyd’s research, including this latest project, which was funded by a $1 million grant from the W.M. Keck Foundation awarded in 2020. Microbes underground don’t use air and sunlight to survive like plants, animals and people do; instead, they consume and process elements from the rocks around them to reproduce and evolve. Drawing those elements out of the surrounding rocky environment requires an external driver. In Boyd’s newest discovery, that driver is earthquakes.

Because a substantial portion – as much as half, by some estimates – of Earth’s microbial biomass resides underground, Boyd said understanding how that life has sustained itself can give insights into not only how that life has evolved, but also the potential for where and how it could reside on other planets.

“If you perturb a system, there will be a response. If you want to understand how our systems work, you need to understand those responses,” he said. “So much of the biomass on Earth is microbial, and if you eliminated that, there would be no higher forms of life. It’s as simple as understanding the food that sustains the microbes that sustain you.”

While conducting research for the project, Boyd was at one point taking real-time measurements of the microbes present in a deep well near Yellowstone Lake, noticing significantly higher levels of sulfur gases than he’d previously measured. When he later looked at the seismic logs for the same time, he realized the sampling had overlapped with the onset of an earthquake swarm, in which several small quakes converge over the same period.

Shaking and fracturing the rocks beneath, the seismic activity altered the supply of elements and nutrients the microbes need to thrive, setting off a chain reaction that resulted in a bloom that changed the microbial composition in the aquifer. For a period of several months, the microbes had much more of the food they needed to grow and reproduce. As the earthquake swarm ceased, the concentration of microbes and elements returned to previous levels.

Deepening understanding of these systems, Boyd said, has been the challenge and opportunity of his career. As it has been for decades, MSU remains a perfect place to study the fundamentals of life through its proximity to Yellowstone’s unique landscapes.

“Every single ecosystem on Earth is ultimately supported by microbes,” Boyd said. “They are the base of all ecosystems as moderators of the geochemical cycles that sustain plant, animal and human health. If half of that base that sustains all life on Earth is in the subsurface, then you better understand how that microbial base has sustained itself.”

-end-

This story is available on the Web at: http://www.montana.edu/news/24951