Wireless telemetry system for single-unit recording in rats navigation

The use of cable systems for neural activity recording limits the measure of behavioral tests in conscious free-moving animals. In particular, cable attachments make it difficult to solve the challenge of a wired measurement system in enclosed spaces such as tunnels or closure mazes. Such environments are of particular interest in investigations of hippocampal place cells, in which neural activity is correlated with spatial position in the environment. In this study, we developed a flexible miniaturized Bluetooth-based wireless data acquisition system and validated it in single-unit recordings of place cells in rats running an enclosed environment over a range of 5 m. The wireless module included an 8-channel analogue front end, digital controller, and Bluetooth transceiver mounted on a backpack. Our flexible bidirectional wireless design allowed all data channels to be previewed at 1 kHz sample rate, and one channel, selected by remote control, to be sampled at 10 kHz. Through careful hardware design, appropriate shielding and avoiding ground loops, interferences from power line and Bluetooth hopping frequency were reduced sufficiently to yield signal quality comparable to that recorded by wired systems. Bluetooth technology thus offers a novel solution for telemetry systems to enable cable-free recordings of place cells.