Engineers at MIT have developed a microelectronic probe that can measure and influence the behavior of neurons involved in the brain-gut axis. Neural communication between the brain and GI tract has been implicated in a range of conditions as varied as autism and Parkinson’s disease. However, studying the interplay between these neurons was difficult, until now. The new microelectronic probes are thin polymer filaments that contain sensors and other microelectronic components, including microfluidic channels to deliver drugs and light sources to perform optogenetics. The probes can be advanced into gastrointestinal or neural tissues to study and influence activity. The MIT team hopes that the technology will reveal new phenomena in a variety of disease states.
The gut and brain communicate a lot, as it turns out, and this does not exclusively involve the brain instructing the gut. Researchers are increasingly appreciating that signals from the gut can also influence our behavior and activity, and the gut-brain axis may play an important role in a variety of diseases.
“There’s continuous, bidirectional crosstalk between the body and the brain,” said Polina Anikeeva, a researcher involved in the study. “For a long time, we thought that the brain is a tyrant that sends output into the organs and controls everything. But now we know that there’s a lot of feedback back into the brain, and this feedback potentially controls some of the functions that we have previously attributed exclusively to the central neural control.”
However, studying this has been difficult to date, and in an effort to shed a little light on the issue, these MIT researchers have designed a new tool. In fact, they had to design the tool, because it didn’t exist. “To be able to perform gut optogenetics and then measure the effects on brain function and behavior, which requires millisecond precision, we needed a device that didn’t exist,” said Atharva Sahasrabudhe, another researcher involved in the study. “So, we decided to make it.”
To create the probes, the researchers used an approach called thermal drawing, which involves drawing out polymer strands into thin filaments. The filaments can also be functionalized with a range of microelectronic devices, including sensors and light sources for optogenetics, along with microfluidic channels that can deliver drugs. Once advanced into neural tissues, the wireless probes are powered and controlled by a small control circuit that can be affixed to the skin.
So far, the researchers have tested the technology in mice, and found that they could significantly influence behavior in the mice by stimulating their gut. “We can now begin asking, are those coincidences, or is there a connection between the gut and the brain?” said Anikeeva. “And maybe there is an opportunity for us to tap into those gut-brain circuits to begin managing some of those conditions by manipulating the peripheral circuits in a way that does not directly ‘touch’ the brain and is less invasive.”
Study in journal Nature Biotechnology: Multifunctional microelectronic fibers enable wireless modulation of gut and brain neural circuits