PLCγ1 dependent neural plasticity is required for dynamic hippocampal CA2 network processing social memory in mice

초록

A growing body of evidence suggests that the hippocampal CA2 region is crucial for processing social memory, including discerning novel social stimuli from familiar ones (retrieving social memory) and becoming familiarized with novel social stimuli (acquiring social memory). Previous studies have shown that the representations of CA2 neural networks differ when presented with familiar versus novel social stimuli. However, the precise moment when a novel stimulus becomes familiar has not been explored. Here, we investigated how the CA2 neural network changes during the acquisition of social stimuli. To achieve this, we imaged the hippocampal CA2 calcium activity in mice in vivo during repetitive presentations of a novel conspecific until it became familiar. We found that the configuration of the hippocampal CA2 neural ensemble changes as the mice become familiarized with the presented conspecific. Interestingly, transgenic mice with Plcg1 knockdown in hippocampal CA2, previously shown to be unable to acquire social memory, did not show changes in the hippocampal CA2 neural ensemble during this repeated exposure to the same conspecific. These results suggest novel mechanisms for how social information is processed in the hippocampal CA2 region.