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Cortex in high resolution Recording brain cortical activity with high spatial and temporal resolution is critical for understanding brain circuitry in physiological and pathological conditions. In this study, Tchoe et al. developed a reconfigurable and scalable thin-film, multithousand-channel neurophysiological recording grids using platinum nanorods, called PtNRGrids, that could record thousands of channels with submillimeter resolution in the rat barrel cortex. In human subjects, PtNRGrids were able to provide high-resolution recordings of large and curvilinear brain areas and to resolve spatiotemporal dynamics of motor and sensory activities. The results suggest that PtNRGrids could be used in the preclinical and clinical setting for high spatial and temporal recording of neural activity. 

Abstract Despite ongoing advances in our understanding of local single-cellular and network-level activity of neuronal populations in the human brain, extraordinarily little is known about their “intermediate” microscale local circuit dynamics. Here, we utilized ultra-high-density microelectrode arrays and a rare opportunity to perform intracranial recordings across multiple cortical areas in human participants to discover three distinct classes of cortical activity that are not locked to ongoing natural brain rhythmic activity. The first included fast waveforms similar to extracellular single-unit activity. The other two types were discrete events with slower waveform dynamics and were found preferentially in upper cortical layers. These second and third types were also observed in rodents, nonhuman primates, and semi-chronic recordings from humans via laminar and Utah array microelectrodes. The rates of all three events were selectively modulated by auditory and electrical stimuli, pharmacological manipulation, and cold saline application and had small causal co-occurrences. These results suggest that the proper combination of high-resolution microelectrodes and analytic techniques can capture neuronal dynamics that lay between somatic action potentials and aggregate population activity. Understanding intermediate microscale dynamics in relation to single-cell and network dynamics may reveal important details about activity in the full cortical circuit. 

Abstract Poly(3,4‐ethylenenedioxythiophene) or PEDOT is a promising candidate for next‐generation neuronal electrode materials but its weak adhesion to underlying metallic conductors impedes its potential. An effective method of mechanically anchoring the PEDOT within an Au nanorod (Au‐nr) structure is reported and it is demonstrated that it provides enhanced adhesion and overall PEDOT layer stability. Cyclic voltammetry (CV) stress is used to investigate adhesion and stability of spin‐cast and electrodeposited PEDOT. The Au‐nr adhesion layer permits 10 000 CV cycles of coated PEDOT film in phosphate buffered saline solution without delamination nor significant change of the electrochemical impedance, whereas PEDOT coating film on planar Au electrodes delaminates at or below 1000 cycles. Under CV stress, spin‐cast PEDOT on planar Au delaminates, whereas electroplated PEDOT on planar Au encounters surface leaching/decomposition. After 5 weeks of accelerated aging tests at 60 °C, the electrodeposited PEDOT/Au‐nr microelectrodes demonstrate a 92% channel survival compared to only 25% survival for spin‐cast PEDOT on planar films. Furthermore, after a 10 week chronic implantation onto mouse barrel cortex, PEDOT/Au‐nr microelectrodes do not exhibit delamination nor morphological changes, whereas the conventional PEDOT microelectrodes either partially or fully delaminate. Immunohistochemical evaluation demonstrates no or minimal response to the PEDOT implant.