Sensing Local Field Potentials with a Directional and Scalable Depth Array: DISC

A variety of electrophysiology tools are available to the neurosurgeon for diagnosis, functional therapy, and neural prosthetics. However, no tool can currently address these three critical recording needs: (i) a surgical method that can reach any cortical region in a minimally invasive manner; (ii) record microscale, mesoscale, and macroscale resolutions simultaneously; and (iii) enable recording from multiple brain regions. This work presents a novel device for recording local field potentials (LFPs) whose form is based on state-of-the-art stereo-electroencephalogram (sEEG). Using quasi-static electromagnetic modeling, the lead body is shown to shield LFP sources and this enables directional sensitivity and scalability when microelectrodes are positioned radially, which we refer to as a DISC array. As predicted, DISC demonstrated significantly improved signal-to-noise, directional sensitivity, and decoding accuracy in the rat barrel cortex during whisker stimulation. Critically, DISC also demonstrated equivalent fidelity at the macroscale and, uniquely, performs current source density in stereo. Directional sensitivity of LFPs may significantly improve brain-computer interfaces and many diagnostic procedures, including epilepsy foci detection and deep brain targeting.