Fig. 1
PACK-mediated optogenetic inhibition of CA1 principal cells in vivo. A–D Experimental design with a timeline. A We targeted PACK (bPAC+Sthk) to excitatory neurons by injecting the AAV9.CaMKIIα vector into the CA1 region of the hippocampus. B After implantations of wire electrodes and an optic fiber into CA1, C we recorded LFPs in freely moving mice for 3 h a day. Reference (ref.) recordings were without illumination, whereas the “0.05 Hz/0.1 Hz recordings” included 1-h pre-recording, light ON phase with 0.05-Hz or 0.1-Hz illumination, and a post-recording. Each recording type was repeated twice and the mean of the two sessions is presented for each animal. D PACK-mCherry expression and electrode/optic fiber positions in CA1 were confirmed by histology at the end of the experiment. E, G, I Representative LFP snippets from the first, second, and third hour of each recording type. E In ref. recordings, LFP magnitude decreased over time, F confirmed by the significant drop of mean line length (in black) in the second and third recording hour. G Applying 10-ms blue light pulses (~ 80 mW/mm2, 460 nm) at 0.05 Hz resulted in an intermittent reduction of LFP magnitude. H Mean line length was significantly reduced during 0.05-Hz light application and in the post-recording. I Applying light pulses at 0.1 Hz resulted in a stable reduction of LFP magnitude, J which is reflected in a robust reduction of line length during 0.1-Hz illumination. One-sample t-test (n = 6 mice, average of 2 recordings, gray lines), *p < 0.05, **p < 0.01, ***p < 0.001. Mean presented in black with SEM as error bars