NYC Gazette

Researchers led by Columbia’s Kristin Baldwin have created mice with hybrid brains—part mouse, part rat—that sense the odors of the world with their rat neurons. The study, published in the journal Cell, marks the first time an animal has been able to use the sensory apparatus of another species to sense and respond accurately to the world.

Baldwin, a professor of genetics & development at Columbia University, explains, “This research is starting to show us how we can expand the flexibility of a brain so that it can accommodate other kinds of inputs, from human-machine interfaces or transplanted stem cells.”

One of the key benefits of these hybrid brains is the potential to enhance understanding of how brain cells function and how they can be repaired or replaced. Baldwin highlights the significance by stating, “Hybrid brains will allow researchers to better understand how brain cells get sick or die and better understand the rules of repairing and replacing parts of the brain.”

The innovative technique used by Baldwin's team involves introducing rat stem cells into mouse blastocysts, resulting in the rat and mouse cells growing together and integrating on their own. This approach, called blastocyst complementation, offers insights into how different species' neurons can coexist and function within a single brain.

The study revealed that the hybrid mice were able to use rat neurons to restore their sense of smell, a crucial function for finding food and avoiding predators. Baldwin shares an interesting observation from the experiments, “We hid a cookie in each mouse cage, and we were very surprised to see that they could find it with the rat neurons."

While the research shows promise in advancing our understanding of brain function and potential treatments for neurological disorders, challenges remain. Baldwin acknowledges that the random distribution of rat cells in each animal poses a hurdle in extending the studies to other sensory and neural systems in the brain. Nevertheless, she remains optimistic about the future possibilities, including the potential to create hybrid brains with primate neurons to further understand human diseases.

The study was supported by various institutions and grants, including the National Institutes of Health and the Cancer Prevention & Research Institute of Texas. Baldwin's involvement in the scientific advisory board of Gameto Therapeutics and other disclosures are noted in the article.