Neural mechanisms of individual recognition
Within a close-knit social group, recognizing an individual as a unique identity and associating and retrieving individual-specific information during social interactions are fundamental abilities for living as a member of the group. Although individual recognition has been reported in many different species, including rodents, its neural underpinnings remain unclear.
We have been developing simplified and precisely controlled individual discrimination paradigms in which subject mice distinguish between stimulus mice based on their individually-unique characteristics. Together with quantitative behavioral measures, we use multiple state-of-art techniques, including two-photon calcium imaging, miniscope imaging, and Neuropixels recordings, to reveal neural mechanisms of social recognition.
Monitoring neuronal activity using a two-photon microscope during individual discrimination
Neural mechanisms of social motivation
– How reward learning improves social information processing in the mPFC and its implications on ASD
Social interactions are often intertwined with rewarding sentiments, giving rise to social motivation. Lack of social motivation is the defining trait of autism spectrum disorder (ASD) and one of its diagnostic criteria. The pathophysiology of ASD is yet unknown; however, one attempt at explaining the pathophysiology of ASD is the social motivation hypothesis. The social motivation hypothesis proposes that ASD manifests from the deficit of representing reward value from social stimuli. Treatments for ASD include behavioral interventions that utilize positive reinforcement as its main strategy.
The medial prefrontal cortex (mPFC) is a central neuroanatomical hub for social and reward circuits. However, the conjunctive association of social and reward information in the mPFC has not been thoroughly studied.
To elucidate how social and reward information is represented, processed, and associated in the mPFC to modulate social motivation, we have been developing a novel social cue-reward association paradigm that allows us to investigate social and reward information processing simultaneously.
Using in vivo calcium imaging, we are monitoring the activity of the mPFC in the cellular and the population levels in WT and ASD model mice. We plan to reveal the interlink between the social and reward representations in the mPFC that is critical for the neural mechanism of social motivation.
Brain-wide computation for social recognition
Social information is composed of cues of different sensory modalities such as vision, audition, and olfaction. Due to this multimodal nature of social information, multiple brain regions such as the prefrontal cortex, hippocampus, and olfactory sensory area are involved in processing it. Neuropixels, a recently developed high-yield recording probe, enables us to record electrical signals of single units across many brain regions, so it has become essential equipment for understanding social recognition involving large brain networks.
Our long-term goal is to elucidate the neural basis of social recognition using the state-of-the-art electrophysiological recording technique. Our lab is performing an experiment where neurons in the multiple brain areas including the prefrontal cortex and hippocampus are simultaneously recorded using two Neuropixels while mice perform an olfactory delayed non-match to sample task.
Neural encoding of mean motion direction in mouse primary visual cortex
There are so many visual stimuli everywhere at every moment. Although it is difficult to recognize all the individual visual stimuli due to the limited brain capacity, life goes on with almost ‘no problem’.
It is well-known that humans can extract statistical features from complex visual stimuli at a brief glance. By extracting mean information from visual stimuli, our sensations can be condensed into meaningful perceptions while reducing the amount of information. However, the neural mechanisms of such function are not understood.
To investigate how and where mean information is represented in the brain, we developed a task in which mice were required to extract mean motion direction from a group dots moving in different directions. We found that neural activity in the mouse primary visual cortex represents the mean motion direction at the individual neuron and population levels.