Talk about thinking small: researchers at Harvard University have devised a new way to implant flexible bioelectronic devices in the embryos of frogs, mice, and lizards, enabling them to monitor brain activity as these creatures develop.
That’s huge!
“Autism, bipolar disorder, schizophrenia – these all could happen at early developmental stages,” Jia Liu, an assistant professor of bioengineering and collaborator on the study, explained. “There is just no ability currently to measure neural activity during early neural development. Our technology will really enable an uncharted area.”
Indeed, it will be the first time researchers track neural activity across the entire brain of a living organism from single cells, throughout its development.
The team described its bioengineering breakthrough in a paper that appeared in Nature last week. It involves seamlessly integrating a flexible biocompatible electrode array that’s been in the works for years into the stem cells of a tadpole’s neural plate, the 2D structure of cells that eventually folds and becomes the brain and spinal cord.
The electronics are embedded in an incredibly soft material called fluorinated elastomer that’s been licensed to and developed by Liu’s startup Axoft Materials; the entire implant is less than a micrometer thick. The mesh of electrodes gradually stretches and distributes throughout the brain, seamlessly integrating with neural tissue without damaging the organ or impeding its function.
This is far more advanced than previous methods of implanting electrodes, which led to neuronal damage. It’s designed to be many orders of magnitude softer than conventional flexible electronics, hold a large number of electrodes, while also reducing damage and lasting a long time inside the body.
So what do these cyborg-like implants tell us?
In the case of frogs, we now know that in its early development phases, neural activity is slow and synchronized across the brain. Later on, different parts of the brain showed distinct and quicker development.
The implants in axolotls – a species of salamanders that can regenerate practically any part of their body when damaged – showed that brain activity greatly increased when their bodies got to work regenerating tails cut off by the researchers. “This suggests that brain activity might play a role in regeneration, “Liu told IEEE Spectrum. “It would be very interesting to see if we can control the central nervous system to facilitate this kind of tissue recovery or injury recovery.”
The scientists also fitted implants into mouse embryos, as well as newborn rats, and managed to record brain activity in them.
This approach could prove instrumental in expanding our understanding of neurodevelopmental disorders in the future. And based on the findings from axolotls, Liu is also excited about the prospect of controlling the central nervous system to encourage tissue recovery.
If you’re into this sort of thing, check out this recent Nature Podcast episode that features the researchers’ work on the implant and embedding it into axolotls.
Source: Harvard John A. Paulson School of Engineering and Applied Sciences
