Figure 5.

Coupling of orange OLEDs to ChrimsonR-expressing neurons for millisecond control of action potential firing. (A) Primary neurons were transduced with lentiviral vectors encoding ChrimsonR, and responses to orange OLED illumination were recorded by patch-clamp. (B) Subthreshold responses to 50 ms illumination in ChrimsonR-expressing cells. Control mock-transduced neurons (WT) showed no responses to light (p < 0.05, Mann-Whitney U-test). (C) Representative subthreshold responses to prolonged (2 s) illumination of ChrimsonR-expressing cells (orange trace) and mock-infected neurons (black trace). (D) Overlay of membrane responses of a single ChrimsonR-expressing neuron to 25 repetitions of 50 ms pulses, successfully triggering action potential firing. (E) Representative traces of neurons successfully firing action potentials during five consecutive 50 ms light stimuli at various inter-stimulus repetition rates. (F) Firing probability vs. stimulus frequency (0.13–6.4 Hz), calculated over first five stimuli per cell (symbols); orange lines represent the group means. (G) Representative spiking activity in response to five trains (each composed of five 1 Hz-stimuli) administered at 0.1 Hz. (H) Firing probability over multiple repetitions (25–100) following the stimulation protocol shown in (G) for individual cells (symbols) and group means (lines). (I) Peristimulus time histogram for the time window 50-ms-before/50-ms-after the stimulus (1 ms bins). (J) Quantification of the delay and jitter of action potential firing based on the first spike per stimulus calculated across all recorded neurons.