Fig. 5: Thermoplasmonic neuromodulation and estimation of network connectivity.
From: Thermoplasmonic neural chip platform for in situ manipulation of neuronal connections in vitro
a Thermoplasmonic NIR stimulation (TP-NIR) by square-patterned illumination. To estimate the network-to-network influence of N1 on N2 (TP-NIR N1 → N2), N1 spiking activity was suppressed by localized thermoplasmonic neural stimulation. b Phase-contrast image of tested network. Agarose micropatterns were 500 μm by 500 μm with a spacing of 100 μm. Scale bar: 50 μm. c Representative raster plots and (d) perievent histograms before, during, and after stimulation with different power densities (30, 140, 243 mW/mm2). TP-NIR N1 and TP-NIR N2 indicate the stimulation of N1 and N2, respectively. Scale bar: 1 min. x-axis: second. y-axis: Hz (spikes/sec). e Spike rate change against power density for TP-NIR N1. The black line (Ctrl) shows rate change in control groups (5 electrodes in unconnected networks) in the same MEA. n = 5 trials for each network. Data are presented as mean ± SD. Two-sided Mann–Whitney test for the values of each network compared with those of control groups at the highest power density (**p < 0.01); p = 0.0079. f Spike rate change against power density for TP-NIR N2. The black line (Ctrl) shows rate change in control groups (5 electrodes in unconnected networks) in the same MEA. n = 5 trials for each network. Data are presented as mean ± SD. Two-sided Mann–Whitney test for the values of each network compared with those of control groups at the highest power density (**p < 0.01); p = 0.0075. g Raster plots of spontaneous activity and examples of inter-network synchronized events (SEs) that spikes propagate from N1 to N2 (arrowhead) and from N2 to N1 (arrow). Red timestamps represent spikes that participated in SEs. Scale bar: 10 s and 500 ms. h Network-to-network influence estimated by thermoplasmonic neuromodulation. i Association degree in inter-network SEs. Red is the percentage of spikes participated in SEs. j Proportion of propagation direction within individual SEs. 106 detected SEs were analyzed. Source data are provided as a Source Data file.
