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Saturday, July 30, 2022

Pinpointing consciousness in animal brain using mouse ‘brain map’

New study identifies network cores of the brain with strong bidirectional connections

UNIVERSITY OF TOKYO

Importance of bidirectionality for consciousness — IMAGE: IT HAS BEEN SUGGESTED THAT THE PART OF THE BRAIN NETWORK SUPPORTING CONSCIOUSNESS BRAIN REGIONS SHOULD BE BIDIRECTIONALLY CONNECTED BECAUSE BOTH FEED-FORWARD AND FEEDBACK PROCESSES ARE NECESSARY FOR CONSCIOUS EXPERIENCE. FOR EXAMPLE, PREVIOUS STUDIES EXAMINING VISUAL PERCEPTION HAVE SHOWN THAT CONSCIOUS PERCEPTION DOES NOT ARISE WHEN THERE IS ONLY FEED-FORWARD PROCESSING, WHEREAS IT ARISES WHEN THERE IS FEEDBACK AS WELL AS FEED-FORWARD PROCESSING. view more
CREDIT: ©2022 JUN KITAZONO

Science may be one step closer to understanding where consciousness resides in the brain. A new study shows the importance of certain types of neural connections in identifying consciousness.

The research, published in Cerebral Cortex, was led by Jun Kitazono, a corresponding author and a project researcher in the Department of General Systems Studies at the University of Tokyo.

“Where in the brain consciousness resides has been one of the biggest questions in science,” said Associate Professor Masafumi Oizumi, corresponding author and head of the lab conducting the study. “Although we have not reached a conclusive answer, much empirical evidence has been accumulated in the course of searching for the minimal mechanisms sufficient for conscious experience, or the neural correlates of consciousness.”

For this study, the team took a step toward identifying the minimally sufficient subnetworks in the brain that support conscious experience.

To identify the areas of the brain where consciousness resides, the researchers looked for one specific hallmark of consciousness within the neural networks of the brain: bidirectional pathways. When we see something or experience a sensation, our brains take in information. This is called a feed-forward signal, but receiving such feed-forward signals is not enough for consciousness. Our brains also need to send information back, in what is called feedback. Not every part of the brain can both receive feed-forward and return feedback information. Researchers hypothesized that these bidirectional connections are an essential hallmark of the parts of the brain responsible for consciousness.

“Feed-forward processing alone is insufficient for subjects to consciously perceive stimuli; rather, feedback is also necessary, indicating the need for bidirectional processing. The feedback component disappears not only during the loss of specific contents of consciousness in awake states, but also during unconscious states where conscious experiences are generally lost, such as general anesthesia, sleep and vegetative states,” said Kitazono. He also explained that it does not matter if you are looking at a human, monkey, mouse, bird or fly; the bidirectionality of processing remains essential.

CAPTION

The proposed algorithm can decompose the entire network hierarchically, into the network part with the strongest bidirectional connections, the part with the second strongest, and so on down the line.

CREDIT

Researchers used a mouse connectome and computational techniques to test their idea. A connectome is a detailed map of the connections in the brain. First, they developed an efficient algorithm to extract the parts of the brain with strong bidirectional connections, called complexes. Then, they applied the algorithm to the mouse connectome.

“We found that the extracted complexes with the most bidirectionality were not evenly distributed among all major regions, but rather are concentrated in the cortical regions and thalamic regions,” said Kitazono. “On the other hand, regions in the other major regions have low bidirectionality. In particular, regions in the cerebellum have much lower bidirectionality.”

These findings align with where scientists have long thought consciousness resides in the brain. The cerebral cortex, located on the surface of the brain, contains sensory areas, motor areas and association areas that are thought to be essential to consciousness experience. The thalamus, located in the middle of the brain, has likewise been thought to be related to consciousness, and in particular, the interaction between the thalamus and cortical regions, called the thalamo-cortical loop, is considered important for consciousness. These results support the idea that the bidirectionality in the brain network is a key to identifying the place of consciousness.

Researchers emphasized that they are still working toward identifying the place of consciousness.

“This study focuses only on ‘static’ anatomical connections between neurons or brain areas. However, consciousness is ‘dynamic,’ changing from moment to moment depending on neural activity,” said Oizumi. “Although anatomical connections tell us how neural activity would propagate and how brain areas would interact, we need to directly investigate the dynamics of neural activity to identify the place of consciousness at any given moment.”

As a next step, he said the team is currently analyzing activity-based networks of the brain in various types of neural recordings.

“The ultimate goal of our lab is to find the mathematical relationship between consciousness and the brain,” said Oizumi. “In this study, we have attempted to relate the network properties of the brain to the place of consciousness. We will further investigate the relationship between consciousness and the brain, toward what is our ultimate goal.”

CAPTION

Conventional neuroscience has studied the relationship of what kind of brain activity r occurs in response to an external stimulus s (e.g., an image of an apple). If we write this relationship using the function f as r=f(s), we can say that clarifying the function f is the main research that conventional neuroscience has been doing. Such research has revealed much about the mechanism of information processing, that is, how the brain processes information from external stimuli. On the other hand, our brain not only processes information from the external world, but also produces the subjective experience of “seeing an apple.” The ultimate goal of the Oizumi Lab is to theoretically understand the subjective experience and consciousness produced by the brain: that is, to clarify the function g that connects brain activity r and consciousness C, where C is the consciousness produced from brain activity r (C=g(r)).

CREDIT

Journal article

Jun Kitazono, Yuma Aoki, Masafumi Oizumi, “Bidirectionally connected cores in a mouse connectome: towards extracting the brain subnetworks essential for consciousness,” Cerebral Cortex: July 21, 2022, DOI: 10.1093/cercor/bhac143

Link: https://doi.org/10.1093/cercor/bhac143

Funding

Japan Science and Technology Agency ACT-X (Grant Number JPMJAX20A6), Japan Science and Technology Agency CREST (Grant Numbers JPMJCR1864 and JPMJCR15E2), AIP challenge program, Japan Science and Technology Agency Moonshot R&D (Grant Number JPMJMS2012), and Japan Society for the Promotion of Science KAKENHI (Grant Numbers 18H02713 and 20H05712) supported this research.

JOURNAL

Cerebral Cortex

DOI

10.1093/cercor/bhac143

ARTICLE TITLE

Bidirectionally connected cores in a mouse connectome: towards extracting the brain subnetworks essential for consciousness

ARTICLE PUBLICATION DATE

21-Jul-2022

Friday, July 29, 2022

Researchers develop new breath-driven concept set to transform access to hand prosthetics

Peer-Reviewed Publication

UNIVERSITY OF OXFORD

Testing during the development process — IMAGE: TESTING DURING THE DEVELOPMENT PROCESS – GATHERING FEEDBACK FROM USERS. view more
CREDIT: CREDIT: MOBILITY INDIA

The new air-powered hand provides a lightweight, low-maintenance and easy-to-use body-powered prosthetic option particularly well suited for children and those in low and middle-income countries.

A revolutionary new hand prosthesis powered and controlled by the user’s breathing has been developed by researchers at the University of Oxford.

The simple lightweight device offers an alternative to Bowden cable-driven body-powered prosthetics initially developed in the early 19th century – particularly for those too young or anatomically unsuited to an uncomfortable harness and cable system.

Senior author Professor Jeroen Bergmann, Department of Engineering Science, University of Oxford said: ‘Our breathing-powered device provides a novel prosthetic option that can be used without limiting any of the user’s body movements. It is one of the ﬁrst truly new design approaches for power and control of a body-powered prosthetic since the emergence of the cable-driven system over two centuries ago.’

Although several different prosthetic options exist (suitability dependent on the level of upper limb difference amongst other factors) little progress has been made in developing new approaches to power and control of body-powered devices compared to sophisticated externally powered prosthetics.

The most widely used functional upper-limb prosthesis remains the cable-driven body-powered system – which can be prohibitively expensive to own and maintain in low-resource settings because of the costs associated with the necessary professional fitting and maintenance.

The new approach, published in the journal Prosthesis, provides an alternative body-powered device for users in situations where cost, maintenance, comfort and ease of use are primary considerations.

By regulating their breathing, users power a small purpose-built Tesla turbine that can accurately control the prosthetic finger movements. The volume of air needed to power the unit can be achieved by young children and the gearing in the unit determines the speed of the grasping action.

Cable and harness free, the device is lightweight and suitable for children and adolescents who are still growing. Minimal maintenance and training are needed for ease of use in comparison to other prosthetic options.

The researchers have been working with LimbBo, a leading UK-based charity for children with limb differences, to develop and refine the device.

Jane Hewitt, Trustee of LimbBo, said: ‘One of our aims at The LimbBo Foundation is to ensure that all our children have access to any devices which will aid their day-to-day lives. No two limb differences are the same and what will help one child will not be suitable for another. Currently, there is some choice available regarding prosthetics but there are still children who need a completely different approach. For many, their lack of an elbow joint severely limits their access to prosthetic devices and so we welcomed the chance to be involved with Professor Jeroen Bergmann to look at different approaches. This is an exciting development for many of our children.’

She added: ‘We welcome this research as a completely different approach to enabling our children to have the help that a prosthetic such as this would give them. The element of choice is important, and we would fully support any research and development plans that enable this. We feel that by including us in discussions the team in Oxford really do want the best for our children.’

A spokesperson from Mobility India, an NGO based in Bengaluru, India working with the researchers on user testing said: ‘The breathing-powered prosthetic (Airbender) has the potential to broaden prosthetic options for children and adolescents, especially in India and other developing countries that lack appropriate technology.’

First author Dr Vikranth H. Nagaraja, Department of Engineering Science, University of Oxford said: ‘Over 40 million individuals worldwide are estimated to have limb differences – most with no access to any form of prosthetic care. Besides, upper-limb prosthetics currently available to patients are often neither affordable nor appropriate, especially in low-resource settings. We hope our research represents a step-change in making prosthetics more widely accessible and helping overcome challenges with current options.’

The full paper, ‘Reimagining prosthetic control: A novel body-powered prosthetic system for simultaneous control and actuation,’ is available in the journal Prosthesis.

ENDS

Testing during the development process – gathering feedback from users.

CREDIT

Credit: Mobility India

Testing during the development process – gathering feedback from users.

CREDIT

Credit: Mobility India

CAPTION

New breath-driven hand prosthetic holding a pen

CREDIT

Credit: University of Oxford

JOURNAL

Prosthesis

DOI

10.3390/prosthesis4030032

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Researchers develop new breath-driven concept set to transform access to hand prosthetics

ARTICLE PUBLICATION DATE

29-Jul-2022

BU researchers find interplay of ancestry and sexual dimorphism significantly affect growth patterns in frontal sinuses

Sinus shape is like fingerprint used by forensic anthropologists in identifying human remains.

Peer-Reviewed Publication

BOSTON UNIVERSITY SCHOOL OF MEDICINE

(Boston) – Located between and above your eyebrows, the frontal sinuses develop in shapes that are as unique to each person as a fingerprint. Since 1925, they’ve been used by forensic anthropologists to help identify human remains when dental or other medical records were missing.

Boston University School of Medicine (BUSM) researchers have found the development of the frontal sinus was affected more by sexual dimorphism than the ancestry of the individual and that it was the interplay between those two factors that produced the most significant variation.

“It is a common drive of people to be curious about ourselves, our backgrounds and our bodies. This study takes a fascinating structure that is as unique to an individual as their fingerprint and starts to shed light on what causes this feature to be so special to each person,” said corresponding author Sean Tallman, PhD, assistant professor of anatomy & neurobiology. Former graduate student Austin Shamlou, MS, now a research technician at Massachusetts General Hospital, is a co-author in the study.

The researchers analyzed computed tomography (CT) images of more than 300 individuals designated as assigned male or assigned female at birth. Individuals also were classified by ancestral backgrounds of African-derived, Asian-derived, European-derived, or Latin American-derived. The authors used Photoshop to create an outline of the frontal sinus layer-by-layer and took measurements of maximum height, width and depth. These frontal sinus outlines were categorized into three groups and compared against variables. The study concluded that when considered separately neither assigned sex nor ancestry significantly affected sinus shape, but there was significant variation in maximum height and maximum depth when the two factors were looked at together.

“Interestingly, the interactive effects of sexual dimorphism and adaptive population histories influence the dimensions of the frontal sinus,” said Tallman, who added that a clear pattern had not yet been found.

Tallman said further research was needed to address the question of why the frontal sinus forms unique structures for every individual. He cautioned that in the U.S. sinus variation did not fall along ancestral lines, suggesting that there was significant overlap in ancestral climates or that climate adaptations no longer impacted variation in the U.S.

These findings appear online in the journal Biology.

JOURNAL

Biology

METHOD OF RESEARCH

Imaging analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Frontal Sinus Morphological and Dimensional Variation as Seen on Computed Tomography Scans

ARTICLE PUBLICATION DATE

29-Jul-2022

US Adults’ Beliefs About Harassing or Threatening Public Health Officials During the COVID-19 Pandemic

Key Points

Question What factors shape US adults’ beliefs regarding whether threatening or harassing public health officials was justified during the COVID-19 pandemic?

Findings In this survey study of 1086 US adults, the share who believed that harassing or threatening public health officials because of business closures was justified rose from 20% to 25% and 15% to 21%, respectively, from November 2020 to July and August 2021. There were increases in negative views over time among higher earners, political independents, those with more education, and those most trusting of science.

Meaning These findings suggest that restoring trust in public health officials will require strategies tailored to engage diverse viewpoints.

Abstract

Importance The rise in attacks on public health officials has weakened the public health workforce and complicated COVID-19 mitigation efforts.

Objective To examine the share of US adults who believed harassing or threatening public health officials because of COVID-19 business closures was justified and the factors shaping those beliefs.

Design, Setting, and Participants The Johns Hopkins University COVID-19 Civic Life and Public Health Survey was fielded from November 11 to 30, 2020, and July 26 to August 29, 2021. A nationally representative cohort of 1086 US adults was included.

Main Outcomes and Measures Respondents were asked how much they believed that threatening or harassing public health officials for business closures to slow COVID-19 transmission was justified. Adjusted differences in beliefs regarding attacks on public health officials were examined by respondent sociodemographic and political characteristics and by trust in science.

Results Of 1086 respondents who completed both survey waves, 565 (52%) were women, and the mean (SE) age was 49 (0.77) years. Overall, 177 respondents (16%) were Hispanic, 125 (11%) were non-Hispanic Black, 695 (64%) were non-Hispanic White, and 90 (8%) were non-Hispanic and another race. From November 2020 to July and August 2021, the share of adults who believed harassing or threatening public health officials because of business closures was justified rose from 20% (n = 218) to 25% (n = 276) (P = .046) and 15% (n = 163) to 21% (n = 232) (P = .01), respectively. In multivariable regression analysis, respondents who trusted science not much or not at all were more likely to view threatening public health officials as justified compared with who trusted science a lot (November 2020: 35% [95% CI, 21%-49%] vs 7% [95% CI, 4%-9%]; P < .001; July and August 2021: 47% [95% CI, 33%-61%] vs 15% [95% CI, 11%-19%]; P < .001). There were increases in negative views toward public health officials between November 2020 and July and August 2021, among those earning $75 000 or more annually (threatening justified: 7 [95% CI, 1-14] percentage points; P = .03), those with some college education (threatening justified: 6 [95% CI, 2-11] percentage points; P = .003), those identifying as politically independent (harassing justified: 9 [95% CI, 3-14] percentage points; P = .01), and those trusting science a lot (threatening justified: 8 [95% CI, 4-13] percentage points; P < .001).

Conclusions and Relevance While antagonism toward public health officials was concentrated among those doubting science and groups most negatively affected by the pandemic (eg, those with lower income and less education), the findings of this study suggest that there has been a shift toward such beliefs within more economically advantaged subgroups and those more trusting of science. Restoring public trust in public health officials will require nuanced engagement with diverse groups.

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US Adults’ Beliefs About Harassing or Threatening Public Health Officials During the COVID-19 Pandemic | Violence | JAMA Network Open | JAMA Network

Association of State COVID-19 Vaccine Mandates With Staff Vaccination Coverage and Staffing Shortages in US Nursing Homes

Key Points

Question Are state COVID-19 vaccine mandates for US nursing home employees associated with staff vaccination coverage and reported staff shortages?

Findings This cohort study of nursing homes in 38 states found that states with a vaccine mandate experienced an increase in staff vaccination coverage compared with facilities in states with no mandate and no worsening of reported staffing shortages following the mandates.

Meaning These findings suggest that given the waning vaccine-induced immunity and low booster dose coverage among nursing home staff in many parts of the US, state mandates for booster doses may be warranted to improve and sustain vaccination coverage in nursing homes.

Abstract

Importance Several states implemented COVID-19 vaccine mandates for nursing home employees, which may have improved vaccine coverage but may have had the unintended consequence of staff departures.

Objective To assess whether state vaccine mandates for US nursing home employees are associated with staff vaccination rates and reported staff shortages.

Design, Setting, and Participants This cohort study performed event study analyses using National Healthcare Safety Network data from June 6, 2021, through November 14, 2021. Changes in weekly staff vaccination rates and reported staffing shortages were evaluated for nursing homes in states with mandates after the mandate announcement compared with changes in facilities in nonmandate states. An interaction between the mandates and county political leaning was considered. Data analysis was performed from February to March 2022.

Exposures Weeks after announcement of a state’s COVID-19 vaccine mandate.

Main Outcomes and Measures Weekly percentage of all health care staff at a nursing home who received at least 1 COVID-19 vaccine dose, and a weekly indicator of whether a nursing home reported a staffing shortage.

Results Among 38 study-eligible states, 26 had no COVID-19 vaccine mandate for nursing home employees, 4 had a mandate with a test-out option, and 8 had a mandate with no test-out option. Ten weeks or more after mandate announcement, nursing homes in states with a mandate and no test-out option experienced a 6.9 percentage point (pp) increase in staff vaccination coverage (95% CI, −0.1 to 13.9); nursing homes in mandate states with a test-out option experienced a 3.1 pp increase (95% CI, 0.5 to 5.7) compared with facilities in nonmandate states. No significant increases were detected in the frequency of reported staffing shortages after a mandate announcement in mandate states with or without test-out options. Increases in vaccination rates in states with mandates were larger in Republican-leaning counties (14.3 pp if no test-out option; 4.3 pp with option), and there was no evidence of increased staffing shortages.

Conclusions and Relevance The findings of this cohort study suggest that state-level vaccine mandates were associated with increased staff vaccination coverage without increases in reported staffing shortages. Vaccination increases were largest when mandates had no test-out option and were also larger in Republican-leaning counties, which had lower mean baseline vaccination rates. These findings support the use of state mandates for booster doses for nursing home employees because they may improve vaccine coverage, even in areas with greater vaccine hesitancy.

Introduction

High COVID-19 vaccination coverage among direct care staff is critical to avoid and manage nursing home COVID-19 outbreaks and deaths,¹^,2 yet many staff remained unvaccinated months after vaccines became available.³ COVID-19 vaccination for nursing home staff serves 3 purposes: (1) to protect residents who are particularly vulnerable to severe infection and may not mount sufficient vaccine-induced immunity,⁴ (2) to protect staff who themselves have experienced a high toll of infection and morbidity,⁵^,6 and (3) to control viral transmission to mitigate nursing home outbreaks.¹^,7 New COVID-19 variants along with low staff vaccination rates in many US nursing homes despite extensive coordinated vaccination campaigns have led several states to implement mandates requiring nursing home employees to be vaccinated against COVID-19.⁸^,9 These state policies were mostly introduced ahead of the federal mandate that was announced as a final rule by the Centers for Medicare & Medicaid Services (CMS) on November 4, 2021.¹⁰

How state COVID-19 vaccine mandates affected nursing home workers is largely unknown. Specifically, it is not clear whether mandates necessarily increased staff vaccination rates, and there are several reasons for this lack of clarity. First, state mandates may include a number of potential exemptions that might allow many workers to remain unvaccinated. A number of states adopted mandates that had a test-out option for employees who wanted to remain unvaccinated for any reason, meaning that staff could choose to submit to additional COVID-19 testing in lieu of receiving the vaccine. Likewise, state policies may allow for medical or religious exemptions from the mandate. Finally, mandates may not have been strictly enforced, thereby allowing out-of-compliance staff to continue working.

How state COVID-19 vaccine mandates affected the supply of nursing home workers is also unclear. Many nursing home leaders have expressed substantial concerns that requiring vaccination as a prerequisite for working in a nursing home may lead many direct care staff to leave the industry, potentially worsening the already severe worker shortages experienced by nursing homes throughout the pandemic.¹¹^,12

Lastly, how the success of state COVID-19 vaccine mandates may be affected by the predominant political preferences of a given geographic location is also unknown. This factor can strongly influence perceptions of vaccines,¹³ and has been shown to correlate strongly with vaccine acceptance and uptake.³^,14^,15 Consequently, mandates may have varying success in terms of achieving their intended policy goal (eg, increasing staff vaccination coverage without worsening staff shortages) in areas with differing political leanings.

A study in Mississippi evaluated how the nation’s first state-level COVID-19 vaccine mandate affected nursing home employees and staff vaccine coverage.¹⁶ The findings indicated that in the weeks after the June 15, 2021, enactment , the nursing home staff vaccination rates increased compared with comparator states without a mandate; however, the gains were modest and failed to raise levels to industry benchmarks. Notably, Mississippi’s policy provided a test-out option for employees.

The purpose of this cohort study was to examine the association of state COVID-19 vaccine mandates with staff vaccination coverage and staffing shortages at nursing homes. We examined these relationships among states with and without test-out options in their mandates and across counties with different political leanings.

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JAMA Health Forum – Health Policy, Health Care Reform, Health Affairs | JAMA Health Forum | JAMA Network

It doesn’t matter much which fiber you choose – just get more fiber!

The human gut evolved to thrive on fermentable fibers, not bacon cheeseburgers

Peer-Reviewed Publication

DUKE UNIVERSITY

DURHAM, N.C. -- That huge array of dietary fiber supplements in the drugstore or grocery aisle can be overwhelming to a consumer. They make all sorts of health claims too, not being subject to FDA review and approval. So how do you know which supplement works and would be best for you?

A rigorous examination of the gut microbes of study participants who were fed three different kinds of supplements in different sequences concludes that people who had been eating the least amount of fiber before the study showed the greatest benefit from supplements, regardless of which ones they consumed.

“The people who responded the best had been eating the least fiber to start with,” said study leader Lawrence David, an associate professor of molecular genetics and microbiology at Duke University.

The benefit of dietary fiber isn’t just the easier pooping that advertisers tout. Fermentable fiber -- dietary carbohydrates that the human gut cannot process on its own but some bacteria can digest -- is also an essential source of nutrients that your gut microbes need to stay healthy.

“We’ve evolved to depend on nutrients that our microbiomes produce for us,” said Zack Holmes, former PhD student in the David lab and co-author on two new papers about fiber. “But with recent shifts in diet away from fiber-rich foods, we’ve stopped feeding our microbes what they need.”

When your gut bugs are happily munching on a high-fiber diet, they produce more of the short-chain fatty acids that protect you from diseases of the gut, colorectal cancers and even obesity. And in particular, they produce more of a fatty acid called butyrate, which is fuel for your intestinal cells themselves. Butyrate has been shown to improve the gut’s resistance to pathogens, lower inflammation and create happier, healthier cells lining the host’s intestines.

Given the variety of supplements available, David’s research team wanted to know whether it may be necessary to ‘personalize’ fiber supplements to different people, since different fermentable fibers have been shown to have different effects on short-chain fatty acid production from one individual to the next.

“We didn’t see a lot of difference between the fiber supplements we tested. Rather, they looked interchangeable,” David said during a tour of his sparkling new lab in the MSRB III building, which includes a special “science toilet” for collecting samples and an array of eight “artificial gut” fermenters for growing happy gut microbes outside a body.

“Regardless of which of the test supplements you pick, it seems your microbiome will thank you with more butyrate,” David said.

The average American adult only consumes 20 to 40 percent of the daily recommended amount of fiber, which is believed to be a root cause behind a lot of our common health maladies, including obesity, cardiovascular disease, digestive disorders and colon cancer. Instead of having to go totally vegetarian or consume pounds of kale daily, convenient fiber supplements have been created that can increase the production of short-chain fatty acids.

The Duke experiments tested three main kinds of fermentable fiber supplements: inulin, dextrin (Benefiber), and galactooligosaccharides (GOS) marketed as Bimuno. The 28 participants were separated into groups and given each of the three supplements for one week in different orders, with a week off between supplements to allow participants’ guts to return to a baseline state.

Participants who had been consuming the most fiber beforehand showed the least change in their microbiomes, and the type of supplement really didn’t matter, probably because they were already hosting a more optimal population of gut bugs, David said.

Conversely, participants who had been consuming the least fiber saw the greatest increase in butyrate with the supplements, regardless of which one was being consumed.

In a second study the David lab performed with support from the U.S. Office of Naval Research, they found that gut microbes responded to a new addition of fiber within a day, dramatically altering the populations of bugs present in the gut and changing which of their genes they were using to digest food.

Using their artificial gut fermenters, the researchers found the gut microbes were primed by the first dose to consume fiber, and digested it quickly on the second dose.

"These findings are encouraging,” said graduate student Jeffrey Letourneau, lead author of the second study. “If you’re a low fiber consumer, it’s probably not worth it to stress so much about which kind of fiber to add. It’s just important that you find something that works for you in a sustainable way.”

“It doesn’t need to be a supplement either,” Holmes added. “It can just be a fiber-rich food. Folks who were already eating a lot of fiber, which comes from plants like beans, leafy greens, and citrus, already had very healthy microbiomes.”

This research was supported by the National Institutes of Health (R01-DK116187, R01DK116187-01); Office of Naval Research (N00014-18-1-2616); NASA Translational Research Institute (NNX16AO69A); and the Damon Runyon Cancer Research Foundation.

CITATIONS: “Microbiota Responses to Different Prebiotics Are Conserved Within Individuals and Associated with Habitual Fiber Intake,” Zachary Holmes, Max Villa, Heather Durand, Sharon Jiang, Eric Dallow, Brianna Petrone, Justin Silverman, Pao-Hwa Lin, Lawrence David. Microbiome, July 29, 2022. DOI: 10.1186/s40168-022-01307-x

“Ecological Memory of Prior Nutrient Exposure in the Human Gut Microbiome,” Jeffrey Letourneau, Zachary Holmes, Eric Dallow, Heather Durand, Sharon Jiang, Verónica Carrion, Savita Gupta, Adam Mincey, Michael Muehlbauer, James Bain, Lawrence David. ISME Journal, July 23, 2022. DOI: 10.1038/s41396-022-01292-x

JOURNAL

Microbiome

DOI

10.1186/s40168-022-01307-x

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Microbiota Responses to Different Prebiotics Are Conserved Within Individuals and Associated with Habitual Fiber Intake

ARTICLE PUBLICATION DATE

29-Jul-2022