Wireless brain computer interfaces enabling synchronized optogenetics and electrophysiology

This paper presents different miniature wireless brain computer interfaces (BCI) enabling synchronized optogenetics and electrophysiology recording for various experimental conditions. These devices, which are entirely built using commercial off-the-shelf components, are validated in-vivo with small transgenic mice. First, a system including 32 electrophysiological recording channels and up to 32 high-power optical stimulation channels is presented. It can process 32 neuronal signals in parallel with high compression ratio using an embedded digital field-programmable gate array (FPGA) signal processor performing spike detection and data compression in-situ. Then, an advanced version featuring equivalent characteristics, but having the third of the size and the weight is presented. The design of a third system dedicated to small freely moving animals is presented. It includes 4 electrophysiological recording channels and 1 high-power optical stimulation channel. In-vivo result obtained in freely moving mice with this system are reported. This latter system performs aggressive data reduction using a resource optimized spike detector running on a low-power microcontroller unit. Finally, a multichannel optical stimulator operating within a network of up to 6 active devices is presented for enabling optogenetic behavioral experiments with several mice at once. These different wireless BCI all provide a multimodal access to brain activity through optogenetics and large-scale electrophysiology.