Summary: A new study identifies a specific class of brain cells—parvalbumin-expressing (PV) interneurons—in the insular cortex as essential regulators of social decision-making and empathic responses. Suppressing these cells in mice disrupted their ability to distinguish between familiar and unfamiliar peers and eliminated their tendency to preferentially approach stressed companions.
The results indicate that PV interneurons function as a neural “switch” within social circuits, adjusting which social targets an animal prefers. Because PV interneuron dysfunction has been associated with neurodevelopmental and psychiatric conditions such as autism spectrum disorder and schizophrenia, these findings offer insight into possible neural mechanisms underlying social deficits in those disorders.
Key Facts
- Social Switch Cells: Parvalbumin (PV) interneurons in the agranular insular cortex modulate whether animals recognize familiar peers and respond empathically to others’ distress.
- Behavioral Effects: When PV interneurons were chemogenetically inhibited, mice no longer showed a preference for novel versus familiar conspecifics and failed to preferentially interact with stressed peers.
- Clinical Relevance: Alterations in PV interneurons have been reported in animal models and human studies of autism and schizophrenia, suggesting translational importance.
Source: Kobe University
Deciding whom to spend time with is a constant part of social life: Should we sit beside a familiar friend on the bus or strike up a conversation with a stranger? Do we pay extra attention to someone who appears distressed? These choices rely on neural circuits that evaluate social information and guide preferences. Developmental or functional deficits in these circuits are linked to social disturbances seen in conditions like autism spectrum disorder and schizophrenia.
TAKUMI Toru, a neuroscientist at Kobe University, and colleagues have been investigating the neural substrates of social behavior and neuropsychiatric disorders. Building on previous work that located neuron clusters active during social interactions, the team focused on PV interneurons—fast-spiking inhibitory neurons known to influence circuit timing and signal processing.
Using genetically modified mice, microendoscopic calcium imaging, and an implanted miniature endoscope, the researchers recorded neuronal activity in the agranular insular cortex in real time while animals engaged in social tasks. They also applied chemogenetic tools to selectively reduce PV interneuron activity and observe the resulting behavioral changes.
Published in Cell Reports in collaboration with SATO Masaaki of Kyoto Institute of Technology, the study reports two key behavioral outcomes when PV interneurons were inhibited. First, mice failed to show normal familiarity-based behavior: whereas control animals typically spent less time with a familiar peer and more time investigating a novel mouse, PV-inhibited mice spent comparable amounts of time with both familiar and unfamiliar conspecifics, indicating an impairment in social recognition or preference.
Second, in tests involving one stressed and one unstressed peer, control mice spent more time near the stressed individual—an apparent consolation or empathic preference. PV-inhibited mice did not show this preference, suggesting PV interneurons are necessary for selecting socially relevant targets based on emotional cues.
Further analysis revealed that a subset of PV interneurons, like pyramidal neurons, increased activity during peer interactions. Suppressing PV interneurons altered how pyramidal neurons encoded interactions with significant social partners and disrupted session-to-session changes in social target specificity. These circuit-level shifts provide a mechanistic link between PV interneuron activity and social preference behavior.
Importantly, in experiments where mice freely interacted with newly met individuals, PV-inhibited mice did not differ from controls, indicating that overall social motivation and basic interaction capability were intact. Instead, PV interneurons specifically influence the selection and prioritization of social targets—decisions about who to spend time with and whom to approach when others are distressed.
Takumi emphasizes the broader implications: “These findings are an important step toward understanding the neural basis of human sociality. Because PV interneuron abnormalities have been observed in model animals and patient brains with autism spectrum disorder and schizophrenia, comparative studies across species could inform future therapeutic strategies.”
Funding: This research was supported by grants from the Japan Society for the Promotion of Science (23K27359, 24H02315, 23K14673, 24H00904, 23H04233, 23KK0132, 24K22036, 24H00620, 24H01241), the Japan Agency for Medical Research and Development (JP21wm0425011), the Japan Science and Technology Agency (JPMJMS2299, JPMJMS229B), the National Center of Neurology and Psychiatry (6-9), the Takeda Science Foundation, and the Taiju Life Social Welfare Foundation. The work was carried out in collaboration with researchers from Hokkaido University and Kyoto Institute of Technology.
About this empathy and social neuroscience research news
Author: Daniel Schenz
Source: Kobe University
Contact: Daniel Schenz – Kobe University
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Parvalbumin interneurons in the insular cortex control social familiarity and emotion recognition” by TAKUMI Toru et al., Cell Reports. DOI: 10.1016/j.celrep.2025.116085
Abstract
Parvalbumin interneurons in the insular cortex control social familiarity and emotion recognition
The insular cortex contributes to multiple aspects of social behavior, but how its inhibitory circuits shape social processing has been unclear. Using cell-type-specific microendoscopic calcium imaging combined with chemogenetic suppression, the authors show that parvalbumin-positive interneurons (PVINs) in the agranular insular cortex (aIC) critically regulate social familiarity and emotion recognition.
A subset of PVINs, like pyramidal neurons (PNs), increases activity during peer interactions. Inhibiting PVINs prevented mice from losing their preference for familiar peers and blocked the normal increase in interactions with stressed individuals. These behavioral changes corresponded with modifications in the proportion of PNs that responded to meaningful social partners and in how individual PNs changed their social target specificity across sessions.
Overall, these findings indicate that PVINs provide context-dependent inhibitory control over socioemotional behavior by locally adjusting PN coding of social information in the aIC, thereby shaping social preferences and empathic responses.