(Solved): Fig 2: interneuron RGC synapse IV curve Fig3 3: RGC vs intemeuron response Some scientists ...

Fig 2: interneuron RGC synapse IV curve ${\mathrm{Fig}}^3$ 3: RGC vs intemeuron response Some scientists are recording from a retinal ganigion cel (RGC), while stimulating a presynaptic intemeuron that expresses infrared-sensitive channelrhodopsins A) Figure 1 shows a postsynaptic potential measured from the RGC to stimulation of the presynaptic intemeuron. Figure 2 shows the I-V relationship of the same intemeuron-RGC synapse obtained in separate experiments. Is this an amacrine cell or bipolar cell?Does it express cationic or anionic ChRs? Explain. B) By how much did optogenetic stimulation alter the interneuron membrane potential? C) The synaptic current underlying this event is $16\mathrm{pA}$ and Rin during illumination is $376\mathrm{MOhms}$. If the single channel conductance of the Channelrhodopsin is $0.1\mathrm{pS}$, how many channels opened? The interneuron has a resting Rin $=500\mathrm{MOhms},\mathrm{Cm}=12\mathrm{pF}$, and the infrared channelrhodopsin used in these experiments has a spectral tuning curve as seen in Fig.4. Some scientists are recording from a retinal ganlgion cel (RGC), while stimulating a presynaptic intemeuron that expresses infrared-sensitive channelrhodopsins A) Figure 1 shows a postsynaptic potential measured from the RGC to stimulation of the presynaptic intemeuron. Figure 2 shows the I-V relationship of the same interneuron-RGC synapse obtained in separate experiments. Is this an amacrine cell or bipolar cell? Does it express cationic or anionic ChRs? Explain. B) By how much did optogenetic stimulation alter the interneuron membrane potential ? C) The synaptic current underlying this event is $16\mathrm{pA}$ and Rin during illumination is $376\mathrm{MOhms}$. If the single channel conductance of the Channelrhodopsin is $0.1\mathrm{pS}$, how many channels opened? The interneuron has a resting Rin $=500\mathrm{MOhms},\mathrm{Cm}=12\mathrm{pF}$, and the infrared channelrhodopsin used in these experiments has a spectral tuning curve as seen in Fig. 4 . D) After the experiment, the scientists use biochemical methods and learn that this intemeuron actually expressed 50000 channels. Given this, how many photons must have struck the interneuron to create the response shown in Fig.1? What was their wavelength? The quantum efficiency of this channelrhodopsin is 0.5 .