Closed-crown packaging system for stable, long-term neural recording in group-housed mice

Long-term recording of neural circuit activity in behaving mice is essential for understanding the pathophysiology of neuropsychiatric disorders and developing effective therapies. However, conventional open-crown packaging leaves cables and connectors exposed, making them vulnerable to biting, mechanical impact, and contamination. In group-housing conditions, these weaknesses often cause cable disconnection or probe damage, forcing single housing and undermining the ecological validity of studies on social behavior. To address these limitations, we developed a closed-crown neural probe packaging system that (i) integrates an NFC-enabled crown for simultaneous physical shielding and individual identification, (ii) employs an ultra-thin PSR-based flexible cable (~35 μm) to ensure mechanical flexibility and stable long-term connectivity, and (iii) incorporates black Pt-electroplated electrodes with low impedance (the tens of kiloohms at 1 kHz) for stable neural recording. After implantation into the hippocampal CA1 region, mice maintained under group-housing conditions exhibited stable impedance over extended periods, with preserved spike waveform and signal-to-noise ratio. Behavioral assessments showed no signs of packaging-induced social stress, and anxiety-related indices were improved in group-housed mice compared with isolated ones. In summary, the proposed closed-crown system provides a robust platform for stable, long-term neural recording under naturalistic social conditions. This approach enables precise examination of neural circuit dynamics in socially interacting animals and offers a powerful tool for advancing the study of social behavior and neuropsychiatric disorders.