High-density mapping of primate digit representations with a 1152-channel µECoG array.

OBJECTIVE Advances in brain-machine interfaces are expected to support patients with movement disorders. Electrocorticogram (ECoG) measures electrophysiological activities over a large area using a low-invasive flexible sheet placed on the cortex. ECoG has been considered as a feasible signal source of the clinical brain-machine interface (BMI) device. To capture neural activities more precisely, the feasibility of higher-density arrays has been investigated. However, currently, the number of electrodes is limited to approximately 300 due to wiring difficulties, device size, and system costs. APPROACH We developed a high-density recording system with a large coverage (14 × 7 mm2) and using 1,152 electrodes by directly integrating dedicated flexible arrays with the neural-recording ASICs (application-specific integrated circuits) and their interposers. MAIN RESULTS Comparative experiments with a 128-channel array demonstrated that the proposed device could delineate the entire digit representation of a nonhuman primate. Subsampling analysis revealed that higher-amplitude signals can be measured using higher-density arrays. SIGNIFICANCE We expect that the proposed system that simultaneously establishes large-scale sampling, high temporal-precision of electrophysiology, and high spatial resolution comparable to optical imaging will be suitable for next-generation brain-sensing technology.