Efficient Kernels for Real-Time Position Decoding from In Vivo Calcium Images

Recent studies have found that the position of mice or rats can be decoded from calcium imaging of brain activity offline. However, given the complex analysis pipeline, real-time position decoding remains a challenging task, especially considering strict requirements on hardware usage and energy cost for closed-loop feedback applications. In this paper, we propose two neural network based methods and corresponding hardware designs for real-time position decoding from calcium images. Our methods are based on: 1) convolutional neural network (CNN), 2) spiking neural network (SNN) converted from the CNN. We implemented quantized CNN and SNN models on FPGA. Evaluation results show that the CNN and the SNN methods achieve 56.3%/83.1% and 56.0%/82.8% Hit-1/Hit-3 accuracy for the position decoding across different rats, respectively. We also observed an accuracy-latency tradeoff of the SNN method in decoding positions under various time steps. Finally, we present our SNN implementation on the neuromorphic chip Loihi.