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Updated: Nov 6, 2025
Behavioral Tasks for Examining Identity Recognition In Mice
Published on: February 7, 2025
Social isolation impairs the prefrontal-nucleus accumbens circuit subserving social recognition in mice
Gaeun Park1, Changhyeon Ryu2, Soobin Kim1
1Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea; Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea.
Abstract:
Although medial prefrontal cortex (mPFC) is known to play important roles in social behaviors, how early social experiences affect the mPFC and its subcortical circuit remains unclear. We report that mice singly housed (SH) for 8 weeks after weaning show a social recognition deficit, even after 4 weeks of resocialization. In SH mice, prefrontal infralimbic (IL) neurons projecting to the shell region of nucleus accumbens (NAcSh) show decreased excitability compared with group-housed (GH) mice. NAcSh-projecting IL neurons are activated when GH mice encounter a familiar conspecific, which is not observed in SH mice. Chemogenetic inhibition of NAcSh-projecting IL neurons in normal mice impairs social recognition without affecting social preference, whereas activation of these neurons reverses social recognition deficit in SH mice. Our findings demonstrate that early social experience critically affects mPFC IL-NAcSh projection, the activation of which is required for social recognition by encoding information for social familiarity.
Insights
Early social isolation in mice impairs social recognition by altering brain circuits. Re-establishing social connections did not fully restore this social recognition ability.
Area of Science:
- Neuroscience
- Behavioral Science
- Social Cognition
Background:
- The medial prefrontal cortex (mPFC) is crucial for social behaviors.
- The impact of early social experiences on mPFC and its subcortical connections is not well understood.
Purpose of the Study:
- To investigate how early social experiences affect the medial prefrontal cortex (mPFC) and its projection to the nucleus accumbens shell (NAcSh).
- To determine the role of the mPFC infralimbic (IL) to NAcSh pathway in social recognition.
Main Methods:
- Mice were singly housed (SH) or group housed (GH) after weaning.
- Social recognition was assessed after 8 weeks of housing and 4 weeks of resocialization.
- Neuronal excitability of IL neurons projecting to NAcSh was measured.
- Chemogenetic techniques were used to manipulate the activity of IL-NAcSh neurons.
Main Results:
- Singly housed mice exhibited a social recognition deficit, persisting even after resocialization.
- SH mice showed decreased excitability in NAcSh-projecting IL neurons compared to GH mice.
- Activation of IL-NAcSh neurons was observed in GH mice during social encounters but not in SH mice.
- Chemogenetic inhibition impaired social recognition, while activation reversed the deficit in SH mice.
Conclusions:
- Early social experience critically shapes the mPFC IL-NAcSh projection.
- The activation of this specific neural pathway is essential for social recognition.
- This pathway encodes familiarity information necessary for recognizing conspecifics.
