Wireless Multimodal Neural Interface Device for Neural Control Studies

Abstract

We present a wireless multimodal neural interface device to record neural activities of neurons in dorsal root ganglia (DRG) and muscle electrical activities (EMG) of the selected muscles of 4 limbs, while selectively manipulating neural activities in DRGs of freely locomoting cats via optogenetic stimulation. The neural interface device has 4 identical 8-channel analog front-end (AFE) circuits for DRG recording with the mid-band gain of 60 dB within 9 Hz - 500 Hz, as well as a 16-channel AFE for EMG recording with the mid-band gain of 40 dB within 0.7 Hz -105 Hz. To effectively stimulate target neurons by optogenetic neuromodulation, the neural interface device has 4 identical 4-channel programmable stimulation drivers that can deliver pulsating current up to 65 mA to the selected LED. To eliminate tethering effects, the neural interface device uses Bluetooth Low Energy radio to receive user-defined stimulation parameters (i.e., stimulation frequency, pulse width, LED current) and send the recording data. The neural interface is built in a form factor of a head-mounted device, or headstage device, which has a plug-in structure formed by two vertical functional boards and one horizontal substrate board, resulting in dimensions of 3 x 3 x 3.3 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and a weight of 6.5 g.