Introducing the brain: bat hippocampal cell uses (Introduction)

by David Turell , Tuesday, October 31, 2023, 19:58 (178 days ago) @ David Turell

All about grid cells and place cells in a variety of uses:

https://www.quantamagazine.org/bats-use-the-same-brain-cells-to-map-physical-and-social...

"The researchers had an idea: that as a bat navigates its physical environment, it’s also navigating a network of social relationships. They wanted to know whether the bats use the same or different parts of their brain to map these intersecting realities.

"In a new study published in Nature in August, the scientists revealed that these maps overlap. The brain cells informing a bat of its own location also encode details about other bats nearby — not only their location, but also their identities. The findings raise the intriguing possibility that evolution can program those neurons for multiple purposes to serve the needs of different species.

"The neurons in question are located in the hippocampus, a structure deep within the mammalian brain that is involved in the creation of long-term memories. A special population of hippocampal neurons, known as place cells, are thought to create an internal navigation system.

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"To gain insight into how the brain might navigate the social environment, Yartsev and his postdoctoral fellow Angelo Forli looked to Egyptian fruit bats, which they had previously used in studies of the brain’s navigation wiring.

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"As expected, the place cells for a given bat changed their activity based on the bat’s location in the cave. Certain place cells fired more frequently when the bat was in a particular spot, while others increased their firing when the bat was someplace else.

"The presence or absence of other bats also influenced the neurons’ firing. As a bat went in for a landing, the place cells behaved differently depending on whether there was a roostmate at the landing site. What’s more, the neurons appeared to encode the identity of specific bats, distinguishing friends from acquaintances. If a bat landed next to a close social contact, the neurons behaved differently than if it landed near a bat it didn’t spend much time with.

"In short, the bats’ navigation system appeared to do double duty as a social map. The mammals weren’t just moving around their home — they were also using the exact same brain cells to track who was on the premises.

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"The discovery immediately spurred questions about whether this reuse of hippocampal place cells applies beyond Egyptian fruit bats in the evolution of the social brain. The hippocampus is an ancient brain structure: It is highly conserved among mammals with diverse lifestyles and degrees of sociality, from largely solitary platypuses to highly communal people. It’s possible that the hippocampus’s navigation system logs the social environment similarly across species. However, it’s equally possible that the place circuitry evolved this dual purpose only in the Egyptian fruit bat. Only additional research can fill in the gaps.

"The findings go beyond the social map. They also fit with the concept of mixed selectivity, Alexander said: the idea that it’s more computationally efficient for single neurons to encode multiple features of the environment.

"In that sense, Forli said, the hippocampus may be like a powerful graphics card in a computer, which can have many uses, from rendering graphics for video games to performing machine learning computations. The hippocampus may be great at particular kinds of computations and may have the ability to be modified or programmed by evolution.

“'We’ve classically thought of the hippocampus as having these [place] cells that code particular locations in space,” Alexander said. “But I think more and more we’re discovering that it’s actually highly adaptive and flexible, and that the hippocampus will code for all sorts of things depending on what you present to it.'”

Comment: not a surprising discovery. The brain is designed to help us navigate our reality.