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. 2016 May 18;6:26181. doi: 10.1038/srep26181

Figure 3. Development of spontaneous firing during a long-term culture of hiPSC-derived cortical neurons.

Figure 3

(A) hiPSC-derived cortical neurons cultured on an MEA chip. (a) Overview of a MEA. (b) Phase contrast image of hiPSC-derived neurons on a MEA chip at 294 DIV. (c) Immunofluorescent image of neurons on a MEA chip at 300 DIV. Images show the soma and neurites using β-tubulin III (green), presynapse formation using synaptophysin (red), and postsynapse formation using PSD-95 (yellow) immunostaining. (B) Changes in spontaneous firing pattern in the same long-term culture at 7, 14, 29, and 34 weeks in vitro (WIV). (a) Typical spontaneous firing patterns. (b) Rasters of the array-wide spike detection rate (AWSDR, spikes/s). Bin size is 1 ms. (c) Corresponding raster plots for all 64 electrodes over 5 min. (C) Electrode grids colored-coded to indicate mean spontaneous firing frequency from same culture at 2, 6, 14, 20, 26, and 34 WIV. Red indicates electrodes with higher firing frequencies. Scale bar in Hz (maximum: 28 Hz). (D) Time course of the average firing frequency per channel from 2 to 34 WIV. Firing frequency (± standard deviation) was calculated as the average of all 64 electrodes from each of the three MEA dishes.