Figure 4
From: Light-evoked hyperpolarization and silencing of neurons by conjugated polymers
Green light stimulation of acute hippocampal slices on MEAs inhibits the high K + -evoked firing activity.
(a) Representative image of an acute cortico-hippocampal slice on MEA. (b,c) Mean (±sem) percent firing changes during (b) and after (c) the light pulse (500 ms, 30 mW/mm2) from all cells recorded in slices placed on MEA:blend or bare MEA (MEA:blend, during −69.77 ± 2.75%, after 56.03 ± 10.87%, n = 84; bare MEA, during −25.06 ± 1.62%, after 12.35 ± 3.22%, n = 162; **p < 0.01, ****p < 0.0001, Mann-Whitney U test). (d) Pie charts representing the activity distribution of neurons in slices layered onto MEA:blend or bare MEA whose firing displayed a statistically significant decrease (black), increase (white) or remained stable (grey) during illumination (MEA:blend vs MEA: decreasing 91.67% vs 48.77%; stable 8.33% vs 51.23%, increasing 0.00% vs 0.00%). The percentage of cell showing a decrease during the pulse on MEA:Blend is statistically significant with respect of those on MEA (p < 0.001, Fisher’s test). For the cell showing a decrease in the firing rate during the light pulse, the distribution after the pulse is also described as part of the whole (MEA:blend vs MEA: decreasing 16.88% vs 3.8%; stable 36.36% vs 64.56%, increasing 46.58% vs 31.64%). (e) The averaged temporal profiles (mean ± sem) of the responses of the neurons on glass:P3HT or glass are shown as PSTH (bins of 50 ms). Black bars: neurons recorded on MEA:blend showing a statistical decrease of the firing activity during the pulse (n = 77); white bars: neurons recorded on bare MEAs (n = 162). The horizontal broken line represents the average baseline value, the horizontal green bar represents the light stimulus.
