Fig. 3: 3D spatial electrophysiology.
a, Modelling of detectable portions of the interface as a function of electrode numbers, by assuming a 100 µm detection distance, across an area coverage of 91%. b, Neural activity measured from an hCO based on data from a subset of 8, 32 and 240 electrodes in the array, to illustrate the numbers necessary to capture meaningful network-level neural processes. c, A schematic illustration of the spatial locations of 240 microelectrodes for 3D reconstruction of neural electrophysiology. d, A surface map of electrophysiological potential across a hCO at a particular moment. e, A surface map of the mean amplitude of neural spikes. f, A surface map of the mean firing rate. g, Recordings and corresponding characteristic waveforms of neural spikes of four different locations within one synchronous wave associated with an hCO. Waveform data are presented as mean values ± s.d. of all spikes within each cluster. Scale bars, 50 ms (horizontal) and 50 μV (vertical) for the potential plots, and 1 ms (horizontal) and 20 μV (vertical) for the waveforms. h, Correlation analysis among 389 recorded neural units of an hCO. i, A 3D connectivity map of correlated units of one example neural unit (left), and strong correlations among all channels (right) of the same hCO as in h. j, A schematic illustration of electrical stimulation and simultaneous calcium fluorescence imaging. k, Brightness analysis of the fluorescence images reveals neural activity of a hCO with no stimulation, with 60-s interval stimulation, with 30-s interval stimulation, and after stimulation. l, Fluorescence imaging of baseline and brightness difference maps with stimulation delivered from a single microelectrode, all microelectrodes of one beam, and all microelectrodes of two beams. Experiments were repeated in three independent hCOs with similar results. a.u., arbitrary units.
