The most obvious maps in our heads are for getting from here to there and back, and we also have varying aptitudes for finding shortcuts. Body maps (for pain, range of movement e.g. for arms and legs, and so on) are fundamentally necessary for survival, for all animals. Similar mapping paradigms seem to also be repurposed for other uses, even for navigating social relationships. That’s what a new Scientific American article is about.
In Search Of The Brain’s Social Road Maps
How do animals, from rats to humans, intuit shortcuts when moving from one place to another? Scientists have discovered mental maps in the brain that help animals picture the best routes from an internalized model of their environments.
Physical space is not all that is tracked by the brain’s mapmaking capacities. Cognitive models of the environment may be vital to mental processes, including memory, imagination, making inferences and engaging in abstract reasoning.
Most intriguing is the emerging evidence that maps may be involved in tracking the dynamics of social relationships: how distant or close individuals are to one another and where they reside within group hierarchies.
Shaping plans also occurs during sleep. Sequences of place cell activity can reactivate during sleep to replay the past or simulate the future. Without the ability to simulate new behaviors, we would have to explore a multitude of real-world options before deciding on what action to take. We would be constant empiricists, only able to act on direct observations. Instead off-line simulations give us the ability to envision possibilities without directly experiencing them.
The progression from the physical to the abstract carries over into the way the brain represents social relationships. Various bits of knowledge about another person are distilled into the concept of that individual. When we see a photograph of someone or hear or see that person’s name, the same hippocampal cells will fire, regardless of the sensory details of the stimulus (for example, the famous “Jennifer Aniston neuron” described by Itzhak Fried of the University of California, Los Angeles, and his colleagues). These hippocampal cells are responsible for representing concepts of specific individuals.
Other hippocampal cells track the physical locations of others and are called social place cells. In an experiment by David Omer of the Hebrew University of Jerusalem, Nachum Ulanovsky of the Weizmann Institute of Science in Rehovot, Israel, and their colleagues, bats observed other bats navigating a simple maze to reach a reward. The task of an observer bat was to simply watch and learn from a navigating bat, enabling it to subsequently navigate the same route to get the same reward. When the observer bat watched, hippocampal cells fired corresponding to the location of the other bat.
Hippocampal activity also tracks social hierarchies: the demands of a boss and a co-worker, for instance, may be valued differently and confer different social standings. Common metaphors illustrate the spatial dimensions of a hierarchy: a person may try to gain status to “climb the social ladder” or “look down” at someone below them. Other factors are also critical. Biological relatedness, common group goals, the remembered history of favors and slights—all determine social proximity or distance. Human relationships can be conceived of as geometric coordinates in social space that are defined by the dimensions of hierarchy and affiliation.