Investigating Lateral Entorhinal Cortex Neuronal Activity During Social Interaction

• Karlee Wickline, Neuroscience, University of Delaware

• Claudia Collins, Psychological and Brain Sciences, University of Delaware
• Devashish Pande, Psychological and Brain Sciences, University of Delaware
• Yichong Ma, Psychological and Brain Sciences, University of Delaware

The hippocampal-entorhinal system plays a central role in encoding experiences and storing them in memory to guide future behavior. The lateral entorhinal cortex (LEC) transmits non-spatial sensory information to the hippocampus. Prior discovery of a direct projection important for social recognition from the LEC to hippocampal CA2 suggests the LEC may contribute to encoding social information. However, how the LEC encodes naturalistic social experiences remains unclear.

To examine whether LEC neuronal activity is modulated during social interaction, we recorded simultaneous video and neural data from animals implanted using a naturalistic social interaction paradigm paired with wireless in vivo electrophysiology. Across six one-hour recording sessions, an adult male mouse was implanted in the LEC with a 32-channel silicon probe and freely interacted with one male and two female mice. Dyadic social interactions were identified using a custom-written social interaction program, and interaction partners were assigned to each interaction bout. Across recording sessions, behavioral measures including interaction frequency, total interaction duration, and percentage of recording time spent interacting were quantified and summarized as mean ± standard deviation. Behavioral analyses for the implanted mouse identified an average of 450 ± 45 social interactions and 12.68 ± 3.46 minutes of social interaction per session. Using a supervised machine learning approach, we extracted chase behavior. A total of 50 chases involving the implant mouse were identified. We recorded a total of 168 well-isolated putative neurons from the entorhinal cortex across six social interaction sessions. Ongoing analyses will investigate LEC activity during social interactions and chase behaviors to explore whether LEC encodes specific social behaviors. These findings will contribute to our understanding of how the entorhinal cortex contributes to social processing and memory.