A hybrid micro-ECoG for functionally targeted multi-site and multi-scale investigation

Brain function relies on coordinated activity across a wide range of spatial and temporal scales. The activity of single neurons depends on their unique pattern of local and long-range connectivity and thus on large-scale patterns of distributed activity across brain-wide networks. Understanding integrated, whole brain function requires new tools capable of recording from anatomically connected populations in distributed brain areas to bridge local and global dynamics. Here, we present high-density, micro-electrocorticography arrays that facilitate multi-scale studies of brain activity. The hybrid arrays integrate the desirable features of silicone elastomers and polyimide films. The silicone elastomer superstructure provides optical transparency and permits repeated penetration with rigid intracortical arrays. The polyimide films enable fine feature definition through photolithography. This combination facilitates high-throughput functional mapping of brain areas to define functionally characterized targets and permits targeted insertion of depth electrodes through the same array for dense local sampling. We demonstrate their suitability for functional mapping of cortical regions in rats, cats and marmosets and the benefit of the resulting functional maps for targeting functionally defined populations for multi-area laminar recordings. Finally, we demonstrate the utility of the hybrid μECoG for local optogenetic stimulation and its use in investigating cortico-cortical interactions through feedforward optogenetic stimulation. Together, these capabilities make the hybrid μECoG a compelling tool for systems neuroscience.