Figure 3

(a) Logarithmic V_RMS amplitude of Tibialis Anterior (TA) motor activity in response to 473 nm, 105 mW/mm² transdermal illumination of the proximal tibia for 4 s at 5 Hz and 10 ms PW for Rag2^−/− and WT rats treated with high dose AAV6. (b) Logarithmic minimum transdermal illumination power needed to elicit transdermal EMG spikes from TA: V_RMS threshold set to 2.45 µV, which was empirically determined to be the max noise level of recordings. (c) Ipsilateral to contralateral side of injection muscle weight ratio at the time of euthanasia for high dose Rag2^−/− and WT rats in both the anterior and posterior compartment muscle groups, representing primarily the TA and Gastrocnemius muscles respectively (n = 5 per group). P = 1E-3 for Ant. Comp. and P = 3E-3 for Post. Comp. (d) Normalized ELISA comparing plasma antibodies against ChR2(H134R)-EYFP for Rag2KO and WT rats at 6 weeks post injection (n = 2 for Rag2KO, n = 5 for WT) and 12 weeks post injection (n = 5 for both groups). P = 8E-4 for 12 week. WT Animal 3 was the only rat which lost transdermal optogenetic expression at week 6. WT Animal 1 was the only rat which maintained expression at week 12. In addition to being included in their respective groups, these animals are also shown separately. (e) ChR2-EYFP+ axon counts as percentage of total axons (left) and as absolutes (right) in tibial nerve (t.n.) and peroneal nerve (c.p.n.) divisions of sciatic nerve of WT and Rag2^−/− rats (n_Rag2−/− = 8, n_WT = 7): P_left = 2E-4. P_right = 3E-3. On left, rats from excitotoxicity control group also included. WT Rat #4 sciatic nerve omitted because was not properly paraffin processed. (f) Sciatic nerve cross sections of representative Rag2^−/− rat (left) and WT rat (right) labeled for ChR2-EYFP (green) and DAPI (blue). Scale bar_left,right = 120 µm, Scale bar_center = 20 µm. Experiment repeated 3 times with similar results.