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The neuroscience behind ‘gut feelings’

Fight or flight? We've all been there. Now we have an understanding of how it works.

  • There is such a thing in neuroscience as a 'gut feeling.'
  • We don't quite know what it's saying yet, but we have an idea.
  • "Gut signals are transmitted at epithelial-neural synapses through the release of … serotonin."

Have you ever had a 'gut feeling?' That moment when you just knew? Did you ever wonder why that was? Research is starting to make inroads towards an answer.

A recent study led by Melanie Maya Kaelberer of Duke along with a team of others looked at mice to determine how the stomach communicated with the brain. Historically, it was believed that the stomach communicated with the brain indirectly — typically through something called neuropeptide signaling (peptides are like proteins but smaller; neurons use neuropeptides to communicate); however, the results from this study suggest something much more direct, much more nuanced, and a little bit more complicated.

Let's break that down — first by quoting the National Institute of Health: "Epithelial cells form barriers that separate different biological compartments in the body." They have a role in regulating what is communicated and what is carried between these different compartments.

Serotonin is a neurotransmitter. A neurotransmitter is a chemical that is released when a signal arrives from somewhere else in the body and acts as a bridge for the signal to move from one neuron to the next.

What makes the result of the study noteworthy is the fact that — in addition to neuropeptides — "further studies revealed that enteroendocrine cells activate sensory neurons within tens to hundreds of milliseconds, a time scale typical of synaptic transmission rather than neuropeptide signaling."

In other words: something arrived in the stomach and it was known, fast. Think of the speed with which your body lets you know that a fly has landed in your skin and think what it means that your body knows what's in its stomach at comparable speeds. (We know that gut bacteria responds to exercise, but this study raises an asterisk of a question all its own: how quickly does gut bacteria respond to exercise in real time?) It's hypothesized that the reason why this happens is to relay where something is in the gut and how it exists in space-time — whether it's just arrived, how it's immediately reacting to the digestive properties of the stomach, and so on.

Benjamin Hoffman and Ellen A. Lumpkin found the results intriguing, writing in a review of the study that it led them to wonder, "What are the molecular mechanisms of neurotransmitter release in enteroendocrine cells?" Who specifically mediates this synaptic transmission? And how are these neuron signals modulated in a stomach full of acid, anyway? What happens when someone has an intestinal disorder?

Perhaps the answer is already known to someone deep within the depths of their gut.

Hints of the 4th dimension have been detected by physicists

What would it be like to experience the 4th dimension?

Two different experiments show hints of a 4th spatial dimension. Credit: Zilberberg Group / ETH Zürich
Technology & Innovation

Physicists have understood at least theoretically, that there may be higher dimensions, besides our normal three. The first clue came in 1905 when Einstein developed his theory of special relativity. Of course, by dimensions we’re talking about length, width, and height. Generally speaking, when we talk about a fourth dimension, it’s considered space-time. But here, physicists mean a spatial dimension beyond the normal three, not a parallel universe, as such dimensions are mistaken for in popular sci-fi shows.

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A new hydrogel might be strong enough for knee replacements

Duke University researchers might have solved a half-century old problem.

Lee Jae-Sung of Korea Republic lies on the pitch holding his knee during the 2018 FIFA World Cup Russia group F match between Korea Republic and Germany at Kazan Arena on June 27, 2018 in Kazan, Russia.

Photo by Alexander Hassenstein/Getty Images
Technology & Innovation
  • Duke University researchers created a hydrogel that appears to be as strong and flexible as human cartilage.
  • The blend of three polymers provides enough flexibility and durability to mimic the knee.
  • The next step is to test this hydrogel in sheep; human use can take at least three years.
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Predicting PTSD symptoms becomes possible with a new test

An algorithm may allow doctors to assess PTSD candidates for early intervention after traumatic ER visits.

Image source: camillo jimenez/Unsplash
Technology & Innovation
  • 10-15% of people visiting emergency rooms eventually develop symptoms of long-lasting PTSD.
  • Early treatment is available but there's been no way to tell who needs it.
  • Using clinical data already being collected, machine learning can identify who's at risk.

The psychological scars a traumatic experience can leave behind may have a more profound effect on a person than the original traumatic experience. Long after an acute emergency is resolved, victims of post-traumatic stress disorder (PTSD) continue to suffer its consequences.

In the U.S. some 30 million patients are annually treated in emergency departments (EDs) for a range of traumatic injuries. Add to that urgent admissions to the ED with the onset of COVID-19 symptoms. Health experts predict that some 10 percent to 15 percent of these people will develop long-lasting PTSD within a year of the initial incident. While there are interventions that can help individuals avoid PTSD, there's been no reliable way to identify those most likely to need it.

That may now have changed. A multi-disciplinary team of researchers has developed a method for predicting who is most likely to develop PTSD after a traumatic emergency-room experience. Their study is published in the journal Nature Medicine.

70 data points and machine learning

nurse wrapping patient's arm

Image source: Creators Collective/Unsplash

Study lead author Katharina Schultebraucks of Columbia University's Department Vagelos College of Physicians and Surgeons says:

"For many trauma patients, the ED visit is often their sole contact with the health care system. The time immediately after a traumatic injury is a critical window for identifying people at risk for PTSD and arranging appropriate follow-up treatment. The earlier we can treat those at risk, the better the likely outcomes."

The new PTSD test uses machine learning and 70 clinical data points plus a clinical stress-level assessment to develop a PTSD score for an individual that identifies their risk of acquiring the condition.

Among the 70 data points are stress hormone levels, inflammatory signals, high blood pressure, and an anxiety-level assessment. Says Schultebraucks, "We selected measures that are routinely collected in the ED and logged in the electronic medical record, plus answers to a few short questions about the psychological stress response. The idea was to create a tool that would be universally available and would add little burden to ED personnel."

Researchers used data from adult trauma survivors in Atlanta, Georgia (377 individuals) and New York City (221 individuals) to test their system.

Of this cohort, 90 percent of those predicted to be at high risk developed long-lasting PTSD symptoms within a year of the initial traumatic event — just 5 percent of people who never developed PTSD symptoms had been erroneously identified as being at risk.

On the other side of the coin, 29 percent of individuals were 'false negatives," tagged by the algorithm as not being at risk of PTSD, but then developing symptoms.

Going forward

person leaning their head on another's shoulder

Image source: Külli Kittus/Unsplash

Schultebraucks looks forward to more testing as the researchers continue to refine their algorithm and to instill confidence in the approach among ED clinicians: "Because previous models for predicting PTSD risk have not been validated in independent samples like our model, they haven't been adopted in clinical practice." She expects that, "Testing and validation of our model in larger samples will be necessary for the algorithm to be ready-to-use in the general population."

"Currently only 7% of level-1 trauma centers routinely screen for PTSD," notes Schultebraucks. "We hope that the algorithm will provide ED clinicians with a rapid, automatic readout that they could use for discharge planning and the prevention of PTSD." She envisions the algorithm being implemented in the future as a feature of electronic medical records.

The researchers also plan to test their algorithm at predicting PTSD in people whose traumatic experiences come in the form of health events such as heart attacks and strokes, as opposed to visits to the emergency department.

Surprising Science

How often do vaccine trials hit paydirt?

Vaccines find more success in development than any other kind of drug, but have been relatively neglected in recent decades.

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