They say the eyes are the window to the soul. On these mice, a transparent skin portal does the job even better.
Scientists have installed small windows into mice's guts to observe their stomachs' nervous systems in real time, according to a study published in the journal Nature Communications.
It may look like something straight out of a sci-fi novel, but in fact, it could help us figure out why so many people have gastrointestinal problems — and how we might be able to treat them.
What the window reveals: The part of the gut the researchers observed is called the enteric nervous system — often referred to as the body's "second brain."
The enteric nervous system controls how food passes through the digestive tract and tells our immune system if something unusual appears. It has five times as many neurons as the spinal cord and can even direct certain organs without communicating with the brain or spinal cord first.
This is an incredibly important part of the body, yet scientists know very little about it — including its role in functional GI disorders, which affect around a quarter of the U.S. population. Functional GI disorders encompass a number of issues, including irritable bowel syndrome, diarrhea, constipation and incontinence.
"If you look at the physiology in these diseases, the gut looks fine," Xiling Shen, associate professor of biomedical engineering at Duke University, said in a statement. "It's the nerves that are somehow malfunctioning. And the reason the term includes so many diseases is because we really don't have any idea what's going on with those nerves."
How the window works: Shen and a team of researchers implanted a window made of borosilicate glass into the skin of a mouse so they could observe the enteric system in real time. Nerves inside the gut light up in green when they fire. The team could record the behavior of neurotransmitters and watch how the gut's "brain" responded to drugs.
Here's what the view looked like:
What's next: Shen hopes the research will lead to better understanding of the enteric system and gut diseases.
"So much is known about the brain and spinal cord because we can open them up, look at them, record the neural activities and map their behaviors," Shen said in the statement. "Now we can start doing the same for the gut.
"We can see how it reacts to different drugs, neurotransmitters or diseases," Shen continued. "We have even artificially activated individual neurons in the gut with light, which nobody has ever done before. This innovation will help us understand this 'dark' nervous system that we currently have completely no idea about."