Human neocortical electrical activity recorded on nonpenetrating microwire arrays: Applicability for neuroprostheses

Object: The goal of this study was to determine whether a nonpenetrating, high-density microwire array could provide sufficient information to serve as the interface for decoding motor cortical signals. Methods: Arrays of nonpenetrating microwires were implanted over the human motor cortex in 2 patients. The patients performed directed stereotypical reaching movements in 2 directions. The resulting data were used to determine whether the reach direction could be distinguished through a frequency power analysis. Results: Correlation analysis revealed decreasing signal correlation with distance. The gamma-band power during motor planning allowed binary classification of gross directionality in the reaching movements. The degree of power change was correlated to the underlying gyral pattern. Conclusions: The nonpenetrating microwire platform showed good potential for allowing differentiated signals to be recorded with high spatial fidelity without cortical penetration.