Kozorez Vladislav/Shutterstock.com

Your 'Gut Feeling' Can Literally Control What Happens in Your Brain

It involves hundreds of millions of neurons that aren’t in your brain.

The brain’s powers are a little overrated. To keep your body going, you don’t need a functioning brain, but you do need something to provide energy. Enter the gut.

We may not give it much thought—because, literally, it happens without conscious thought—but the process of extracting energy from food is an intricate one. It involves hundreds of millions of neurons that aren’t in your brain. Those neurons are found in the outer layers of your gut, and the enteric nervous system they form is so powerful that it can work without any direct input from the brain.

The actions this nervous system performs include ensuring food passes at regulated speed, getting the right juices secreted to make digestion easier, and managing the mucus of the intestinal lining. These are crucial functions. And in the past decade, we have learned just how much of an impact the gut can have on the rest of the body and the mind.

Command and control

For instance, the processes the enteric nervous system performs also gives it some control over the trillions of microbes that sit in your gut. Many of them are essential for our health, because they help us extract nutrients that we wouldn’t otherwise be able to, and some even fend off infections.

One way enteric neurons control these microbes is by changing the thickness of the mucus lining. Justin and Erica Sonnenburg, researchers at Stanford University and authors of The Good Gutsay this process is similar to how “creatures adapted to a moist rain forest would struggle in the desert.” Depending on what kinds of microbes are best suited for a job, the mucus lining can determine their population in the gut.

Layers of the gastrointestinal tract.(Goran tek-en/Wikimedia CC-BY)

And there’s more. It had been suspected that what happens in the gut could have an impact on the brain. Now we have found too many correlations to ignore the gut-to-brain connection.

2011 study split a group of mice based on their personality: timid vs adventurous. Then the researchers took another set of mice with microbe-free guts. In half, they installed the microbiome of timid mice, and in the other half they placed the microbiome of adventurous mice. Lo and beholdthose germ-free mice took on the personality traits of the microbiome-owner.

In a 2013 study, using another mice model, researchers at the California Institute of Technology found that mice with autistic features—such as stress, anti-social nature, and troubling gastrointestinal symptoms—had much lower levels of Bacteroides fragilis than normal mice did. Worse still, when injected a chemical (4-ethylphenylsulphate) found in the guts of autistic mice in to normal mice, they developed autistic symptoms too.

In a 2014 study, researchers at University College Cork found that mice born via C-sections were found to have a greater risk of suffering from depression than mice born vaginally. Turns out, the C-section mice had far less diverse species of microbes in their gut, most likely because they couldn’t pick up the beneficial microbes found in their mother’s vagina.

Although mice are easier to manipulate, such connections are not limited to mice alone. In a 2013 study, researchers at Arizona State University found that humans with behavioral conditions, such as autism, had significant differences in their gut microbiome as compared to more normal humans.

Until now, however, these gut-brain connections have been mere correlations. With some help from tapeworms, a new study changes that.

Tapeworms to the rescue

One of the connecting factors between the brain and the gut has been the immune system. Neurological diseases, such as Alzheimer’s and multiple sclerosis, are linked to changes in the immune system, and auto-immune diseases of the gut, such as Crohn’s disease, are linked to mental illnesses.

Now a new study published in published in Brain, Behavior and Immunity has made use of this immune-system connection to show how the gut can have an impact on the brain. To trigger this connection, Staci Bilbo, a neuroscientist at Duke University, and her colleagues used tapeworms and showed how these nasty creatures can stop memory loss.

Hymenolepis diminuta.(CDC)

She split a group of 30 rats in two: those infected with the Hymenolepis diminutaworm and those without. Then, in both groups, she induced a second infection aimed at increasing the production of a brain signaling chemical called IL-1β. The chemical is usually beneficial, but in excess it can cause damage and has been associated with brain disease.

To test their memories, the rats were put in a room and were allowed to become familiar with it. Then Bilbo gave them a shock so that they would connect the room with bad memories. The next day she re-introduced both wormed and un-wormed rats in the room.

She found that mice with tapeworms were twice as likely to recoil from the room as rats that did not have worms. So the tapeworm infection seems to have protected the mice from memory loss, as compared to infection-free mice.

Good gut, good brain

The reason was that mice with tapeworm infection had already had an immune response, which kept the levels of IL-1β low when a second infection came along. Lower levels of IL-1β in the brain ensured the formation and retention of memories, more than in rats without the worms. Those who hadn’t had the infection produced far greater levels of IL-1β.

This kind of effect is called “biome depletion,” where a lack of exposure to infections causes immune systems to overreact to infections later in life. Thus exposure to some microbes can help avoid such a response, and, in the case of the rats, help prevent memory loss.

To be sure, tapeworm infections can be nasty, and nobody is recommending that you ingest some to protect against memory loss. The circuitous route taken was to come to a definitive conclusion that the changes in the gut can trigger changes in the brain.

The evidence from Bilbo’s study is among the first to draw a causal link. And more is sure to come. In 2014, the US National Institutes for Mental Health spent about $1 million on research looking at the microbiome-brain connection.

In comparison to the many billions of neurons in the brain, the gut’s hundreds of millions might not seem like much. And, yet, it’s quite clear “gut feelings” are no longer just a metaphor.

(Image via Kozorez Vladislav/Shutterstock.com)

X
This website uses cookies to enhance user experience and to analyze performance and traffic on our website. We also share information about your use of our site with our social media, advertising and analytics partners. Learn More / Do Not Sell My Personal Information
Accept Cookies
X
Cookie Preferences Cookie List

Do Not Sell My Personal Information

When you visit our website, we store cookies on your browser to collect information. The information collected might relate to you, your preferences or your device, and is mostly used to make the site work as you expect it to and to provide a more personalized web experience. However, you can choose not to allow certain types of cookies, which may impact your experience of the site and the services we are able to offer. Click on the different category headings to find out more and change our default settings according to your preference. You cannot opt-out of our First Party Strictly Necessary Cookies as they are deployed in order to ensure the proper functioning of our website (such as prompting the cookie banner and remembering your settings, to log into your account, to redirect you when you log out, etc.). For more information about the First and Third Party Cookies used please follow this link.

Allow All Cookies

Manage Consent Preferences

Strictly Necessary Cookies - Always Active

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Sale of Personal Data, Targeting & Social Media Cookies

Under the California Consumer Privacy Act, you have the right to opt-out of the sale of your personal information to third parties. These cookies collect information for analytics and to personalize your experience with targeted ads. You may exercise your right to opt out of the sale of personal information by using this toggle switch. If you opt out we will not be able to offer you personalised ads and will not hand over your personal information to any third parties. Additionally, you may contact our legal department for further clarification about your rights as a California consumer by using this Exercise My Rights link

If you have enabled privacy controls on your browser (such as a plugin), we have to take that as a valid request to opt-out. Therefore we would not be able to track your activity through the web. This may affect our ability to personalize ads according to your preferences.

Targeting cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising.

Social media cookies are set by a range of social media services that we have added to the site to enable you to share our content with your friends and networks. They are capable of tracking your browser across other sites and building up a profile of your interests. This may impact the content and messages you see on other websites you visit. If you do not allow these cookies you may not be able to use or see these sharing tools.

If you want to opt out of all of our lead reports and lists, please submit a privacy request at our Do Not Sell page.

Save Settings
Cookie Preferences Cookie List

Cookie List

A cookie is a small piece of data (text file) that a website – when visited by a user – asks your browser to store on your device in order to remember information about you, such as your language preference or login information. Those cookies are set by us and called first-party cookies. We also use third-party cookies – which are cookies from a domain different than the domain of the website you are visiting – for our advertising and marketing efforts. More specifically, we use cookies and other tracking technologies for the following purposes:

Strictly Necessary Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Functional Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Performance Cookies

We do not allow you to opt-out of our certain cookies, as they are necessary to ensure the proper functioning of our website (such as prompting our cookie banner and remembering your privacy choices) and/or to monitor site performance. These cookies are not used in a way that constitutes a “sale” of your data under the CCPA. You can set your browser to block or alert you about these cookies, but some parts of the site will not work as intended if you do so. You can usually find these settings in the Options or Preferences menu of your browser. Visit www.allaboutcookies.org to learn more.

Sale of Personal Data

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.

Social Media Cookies

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.

Targeting Cookies

We also use cookies to personalize your experience on our websites, including by determining the most relevant content and advertisements to show you, and to monitor site traffic and performance, so that we may improve our websites and your experience. You may opt out of our use of such cookies (and the associated “sale” of your Personal Information) by using this toggle switch. You will still see some advertising, regardless of your selection. Because we do not track you across different devices, browsers and GEMG properties, your selection will take effect only on this browser, this device and this website.