Recognizing and remembering individuals is crucial for a social species such as ourselves. But how does our brain identify an individual and then "place them" so we know who they are?
Two Processes of Social Memory: The Butcher on the Bus
Picture riding the bus, observing those around you. Your eyes come across a familiar face, and you think, "I know that person, but from where?" After some thought, you recollect the person from a completely non-bus related context: "That's my butcher, and I bought food from them on Tuesday!"
There are two processes of social memory described by "The Butcher on the Bus" story. Getting from recognition ("I know that person") to the recollection of past experiences ("They gave me some great advice for my brisket") relies on distinct and complex cellular interactions.
The satisfaction you feel after "placing" someone is well deserved, considering the high level of intricate activity your hippocampus just performed, according to a recent study out of Columbia University by Lara M. Boyle and colleagues.
Recognizing and Remembering by CA2 Neurons
In their study published in Neuron, Boyle et al. focus on the CA2 region in the hippocampus —an area not fully understood, yet believed to be crucial for processing social cues.
The researchers use a common scenario—a familiar individual in an unexpected place—to explore social memory. Using mice as model organisms, Boyle et al. employ cutting-edge techniques to monitor the real-time firing of neurons within the CA2 region. The researchers gain invaluable insights into the neural substrates of social memory processing by presenting the mice with both novel and familiar counterparts in various social contexts.
More Insight on How Our Brains Process Social Information
Boyle and her team observed that as mice become more familiar with other mice, the patterns of neural activity in the CA2 region and the mathematical models that describe it become increasingly complex. This heightened complexity, termed "dimensional geometry," correlates directly with the mice's ability to recognize familiar conspecifics. Low-dimensional geometry is sufficient to identify a familiar individual, but to get you to that butcher on the bus level, high-dimensional geometry between CA2 neurons becomes necessary.
Implications and Future Directions in Social Memory
Understanding how our brains remember someone and our past experiences with that individual could help us understand conditions like autism and schizophrenia, which affect social interactions.
It also sheds light on an essential aspect of human cognition. As research continues, we may uncover more about how our brains make sense of the social world.
Sources: Neuron, Nature Reviews Neuroscience