Summary: A newly developed system uses wireless technology to remotely activate specific brain networks in fruit flies in less than a second.
Source: Rice University
A research team led by Rice University’s neuroengineers has created wireless technology to remotely activate specific brain circuits in fruit flies in under a second.
In a published demonstration in Natural materialResearchers from Rice, Duke University, Brown University and Baylor College of Medicine used magnetic signals to activate targeted neurons that controlled the body position of freely moving fruit flies in an envelope.
“To study the brain or to treat neurological disorders, the research world is looking for tools that are both incredibly accurate but also minimally invasive,” said study author Jacob Robinson, associate professor of electrical and computer technology at Rice and a member of Rice’s Neuroengineering Initiative.
“Remote control of selected neural circuits with magnetic fields is something of a holy grail for neurotechnology. Our work takes an important step towards that goal because it increases the speed of magnetic remote control, making it closer to the natural speed of the brain.”
Robinson said the new technology activates neural circuits about 50 times faster than the best previously demonstrated technology for magnetic stimulation of genetically defined neurons.
“We made progress because the lead author, Charles Sebesta, had the idea of using a new ion channel that was sensitive to the rate of temperature changes,” Robinson said.
“By bringing together experts in genetic engineering, nanotechnology and electrical engineering, we were able to put all the parts together and prove that this idea works. This was truly a team effort by world-class researchers that we were fortunate to work with.”
The researchers used genetic engineering to express a special heat-sensitive ion channel in neurons that cause flies to partially spread their wings, a common mating gesture.
The researchers then injected magnetic nanoparticles that could be heated with an applied magnetic field. An overhead camera looked at flies as they roamed freely in a casing on top of an electromagnet. By changing the magnetic field in a specified way, the researchers were able to heat the nanoparticles and activate the neurons.
An analysis of video from the experiments showed that flies with the genetic modifications adopted the wing-scattered posture within about half a second after the change in the magnetic field.
Robinson said that the ability to activate genetically targeted cells at precise times can be a powerful tool for studying the brain, treating diseases and developing direct brain-machine communication technology.
Robinson is the lead investigator at MOANA, an ambitious project to develop headset technology for non-surgical, wireless, brain-to-brain communication. MOANA is an abbreviation for “magnetic, optical and acoustic neural access” and is funded by the Defense Advanced Research Projects Agency (DARPA) to develop headset technology that can both “read” or decode neural activity in a person’s visual cortex and “write,” or code, that activity in another person’s brain.The magnetogenetic technology is an example of the latter.
Robinson’s team is working towards a goal of partially restoring vision for patients who are blind. By stimulating parts of the brain associated with vision, MOANA researchers hope to be able to give patients a sense of sight even when their eyes are no longer functioning.
“The long-term goal of this work is to create methods to activate specific parts of the brain in humans for therapeutic purposes without ever having to perform surgery,” Robinson said. “To get to the natural precision of the brain, we probably need to get an answer down to a few hundredths of a second. So there is still a way to go.”
Co-authors of the rice study include Sebesta, Daniel Torres Hinojosa, Joseph Asfouri, Guillaume Duret, Kaiyi Jiang, Linlin Zhang, Qingbo Zhang and Gang Bao. Additional co-authors include Boshuo Wang, Zhongxi Li, Stefan Goetz and Angel Peterchev of Duke; Zhen Xiao and Vicki Colvin of Brown; and Herman Dierick from Baylor.
Financing: The research was funded by DARPA (N66001-19-C-4020), National Science Foundation (1707562), Welch Foundation (C-1963) and National Institutes of Health (R01MH107474).
About this neurotechnical research novelty
Original research: Closed access.
“Second, multi-channel magnetic control of selected neural circuits in freely moving flies”By Jacob Robinson et al. Natural material
Second, multi-channel magnetic control of selected neural circuits in freely moving flies
Precise timed activation of genetically targeted cells is a powerful tool for studying neural circuits and controlling cell-based therapies.
Magnetic control of cell activity, or “magnetogenetics”, using magnetic nanoparticle heating of temperature-sensitive ion channels enables remote, non-invasive activation of neurons for deep tissue applications and free-range animal studies.
However, the in vivo response time for thermal magnetogenetics is currently tens of seconds, which prevents precise time modulation of neural activity. In addition, magnetogenetics has not yet achieved in vivo multiplexed stimulation of different groups of neurons.
Here we produce subsecond behavioral responses in Drosophila melanogaster by combining magnetic nanoparticles with a speed-sensitive thermoreceptor (TRPA1-A). In addition, by setting magnetic nanoparticles to respond to different magnetic field strengths and frequencies, we achieve subsecond, multi-channel stimulation.
These results bring magnetogenetics closer to the temporal resolution and multiplexed stimulation possible with optogenetics while maintaining the minimal invasiveness and deep tissue stimulation possible only by magnetic control.
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