Brain-implantable needle-type CMOS imaging device enables multi-layer dissection of seizure calcium dynamics in the hippocampus

Current neuronal imaging methods use bulky lenses that either impede animal behavior or prohibit multi-depth imaging. To overcome these limitations, we developed a lightweight lensless biophotonic system for neuronal imaging, enabling compact and simultaneous visualization of multiple brain layers. Our developed "CIS-NAIST" device integrates a micro-CMOS image sensor, thin-film fluorescence filter, micro-LEDs, and a needle-shaped flexible printed circuit. With this device, we monitored neuronal calcium dynamics during seizures across the different layers of the hippocampus. The CIS-NAIST device revealed distinct calcium activity patterns across the CA1, molecular interlayer, and dentate gyrus. Our findings indicated an elevated calcium amplitude activity specifically in the dentate gyrus compared to other layers. Then, leveraging the multi-layer data obtained from the device, we employed machine learning techniques for seizure classification and prediction. Using Long-Short Term Memory and Hidden Markov Models, we successfully classified seizure calcium activity and predicted seizure behavior based on the multi-layer imaging data. Taken together, our device can enable a minimally invasive method of seizure monitoring that can help elucidate the mechanisms of temporal lobe epilepsy.&#xD.