Amazing stuff!
"... The research ... focused on the hippocampus — the part of the brain responsible for spatial navigation and social memory.
While scientists knew the hippocampus served both these functions, they previously thought these might be separate processes handled by different neurons. What this study unveiled is that the same neurons can simultaneously track where others are located AND their social relationships, creating a holistic social-spatial map. ..."
From the editor's summary and abstract:
"Editor’s summary
Classic work on cognitive maps has shown that neurons in the hippocampus code an organism’s environment and their place within it. However, most organisms, and especially social species, exist in complex worlds that include not just their place in their environment, but also the place and identity of other individuals relative to themselves. Ray et al. monitored fruit bats within a naturalistic environment and found that neurons in the hippocampus also coded for distinct individuals, including their sex, rank, location, and unique identity. Thus, the hippocampus creates not only an individual’s cognitive map, but also a complex map of their social environment. ...
Structured Abstract
INTRODUCTION
Social animals live in groups and interact volitionally in complex ways. To perform real-life social behaviors, the brain needs to code other individuals’ identities, represent various types of social interactions, and encode key social factors such as the sex, dominance hierarchy, and social affiliation of multiple other individuals. However, our understanding of how the brain deals with such diverse requirements stems from constrained laboratory experiments in which an animal typically exhibits one specific behavior with one other animal in one particular task. This leaves the fundamental question unexplored: How does the brain actually represent the real world with its complex, multianimal settings?
RATIONALE
To understand natural social coding in the mammalian brain, we studied Egyptian fruit bats (Rousettus aegyptiacus), which are highly social mammals, and focused on the hippocampus, a brain area that in previous studies has been shown to be important for memories of social identities, episodic events, and spatial locations. We hypothesized that in natural scenarios, when all of these disparate aspects occur simultaneously, hippocampal neurons would bind together all of these different types of information.
To create a naturalistic environment, we established a laboratory-based “cave,” housing mixed-sex groups of five to 10 wild-caught bats. The bats lived together continuously (24/7) for several months, engaging in natural social behaviors without any imposed tasks. During this time, we conducted wireless neural recordings from the dorsal hippocampus area CA1 of both male and female bats and tracked their positions, head directions, and social interactions with each other.
RESULTS
The freely behaving bats formed a stable social network and displayed three key behaviors:
(i) flying between two nets located at opposite corners of the setup,
(ii) engaging in social interactions, and
(iii) being active on the net and observing each other.
We found that hippocampal “place cells,” neurons known to represent the animal’s own position, were modulated during flight by the social context, i.e., whether the bat was flying to meet another bat or to be alone. These cells also encoded the identities of other bats. This identity coding was invariant to the bat’s flight direction.
We also found that many hippocampal cells encoded social-interaction events, with different neurons typically encoding distinct types of social interactions such as affiliative grooming or aggressive boxing.
During active observation on the nets, we used methods from machine learning and game theory to reveal that neurons encoded the bat’s own position and head direction, together with the positions, directions, and identities of multiple other individuals.
Identity-coding neurons encoded the same specific bat across different locations and different behavioral states, both in-flight and on the net, providing another example of social invariance. The strength of identity coding was modulated by the sex, dominance hierarchy, and social affiliation of the other bats.
CONCLUSION
Our use of a naturalistic social colony allowed us to discover that the classical hippocampal cognitive map of space also integrates rich social information, forming a sociospatial cognitive map. We found neurons that encoded social interaction events, identities and sex of other individuals, dominance hierarchy, and social affiliation, along with the position and direction of both self and others. These findings combine the historically disparate views on hippocampal function, which suggested that the hippocampus is important for encoding memory, social identity, or spatial maps. Here, we have shown that all of these factors are represented together in the same neural network."
Scientists find brain's social GPS in pioneering bat study - ISRAEL21c "The finding could help us understand how animals and humans navigate social relationships, potentially leading to new treatments for social disorders."
Hippocampal place cells also encode social information, forming a sociospatial cognitive map.
