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. Author manuscript; available in PMC: 2023 Mar 2.
Published in final edited form as: Neuron. 2022 Jan 5;110(5):783–794.e6. doi: 10.1016/j.neuron.2021.12.003

Figure 1: Optogenetic stimulation of isolated CA1PCs at a fixed location rapidly induces new PF formation.

Figure 1:

(A) Top, Schematic of 2p-guided single cell electroporation. Bottom, Example electroporation of a single CA1PC in vivo. (B) Expression of GCaMP7b and ChRmine-mScarlet in a CA1PC ~ 48H after electroporation. Maximum intensity projection (Z-MIP; z-depth 58 um) shows expression in neurites as well as soma. (C) Left, Schema of circuit with CA1PCs (triangles) and local INs (blue circle) during widefield optogenetic stimulation. Right, Schematic of behavior apparatus and opto-PFi protocol; 1 sec widefield LED stimulation is triggered at a fixed spatial location (SZ) for 5 consecutive laps as mice run on a cued linear treadmill for randomly-delivered water rewards. (D) Left, peri-SZ fluorescence (z-scored) of an example CA1PC before (PRE), during (STIM), and after (POST) induction of a de novo PF, with next day (24H) follow-up. Within-session lap numbers are indicated next to each fluorescence trace. Highlighting indicates 1 second after SZ entry, red indicates LED on. Right, raster of the running-related activity (deconvolved events) of the same cell during first 20 laps of induction session and 24H follow-up session. Vertical line indicates SZ (position 0). Horizontal lines demarcate induction session epochs. (E) Mean tuning curve of all cells by session block, centered on SZ (vertical line). (F) Mean change in spatial firing activity from PRE to POST session blocks (centered on SZ, vertical line). (G) Left, activity centroid distance of cells to SZ (mean ± sem; PRE: 59.42 ± 8.84, POST 27.58 ± 8.44, 24H: 42.12 ± 8.95, 48H: 44.58 ± 12.46, 72H 46.37 ± 8.51; POST: p = 0.0383, One-sample Student’s t-test against null hypothesis of 48.5 cm). Colored points indicate cells with peri-SZ PF. Right, activity centroid distance shift toward SZ after induction protocol (POST - PRE mean ± sem; 31.84 ± 11.37, p = 0.0231, One-sample Student’s t-test against null hypothesis of 0 cm). (H) Left, within-PF tuning curve peak location relative to SZ for successfully induced (7/9) cells (−10.88 ± 2.16; p = 0.0023, One-sample Student’s t-test against null hypothesis of 0 cm). Right, correlation of induced PF width to peri-SZ velocity during first stimulation (pearson’s r=0.943, p = 0.0014). For (E-F) data is shown for all stimulated cells (n = 9 cells, 7 mice). For (H) data is shown only for cells with successfully induced peri-SZ PF (n = 7 cells, 6 mice). All boxes indicate median and interquartile range.