Flexible and transparent microelectrode arrays for simultaneous fMRI and single-spike recording in subcortical networks.

Current techniques of neuroimaging, including electrical devices, are either of low spatiotemporal resolution or invasive, impeding multiscale monitoring of brain activity at both single-cell and network levels. Overcoming this issue is of great importance to assess the brain's computational ability and for neurorehabilitation projects that require real-time monitoring of neurons and concomitant network activities. Currently, that information could be extracted from functional MRI when combined with mathematical models. Novel combinations of measurement techniques that enable quantitative and long-lasting recording at both single cell and network levels will enable to correlate the MRI data and single cell activity to refine those models. Here, we report the fabrication and validation of ultra-thin, optically transparent, and flexible subcortical microelectrode arrays for combining functional MRI and multisite single-spike recordings. The sensing devices demonstrate both fMRI transparency at 4.7 T and high electrophysiological performance, and thus appear as a promising candidate for simultaneous multiscale neurodynamic measurements.