Journal: bioRxiv

Article Title: A novel, evolutionarily conserved inhibitory circuit selectively regulates dentate gyrus mossy cell function

doi: 10.1101/2025.07.09.663808

Figure Lengend Snippet: A) Diagram of imaging cannula for in vivo 2-photon imaging of DG. B) Diagram of focal plane for GCL (left) and hilar (left) imaging (top). Time-averaged 2-photon images of GCL and hilus (bottom). C) Schematic of imaging setup with virtual reality. The mouse is head-fixed running on top of a floating ball while the virtual environment is projected on a dome that surrounds the mouse. D). Image of familiar virtual reality environment. E) Diagram of viral injections for chemogenetic activation of VGluT3+ cells and GCaMP imaging of MCs/GCs (top). Representative fluorescence traces from MCs during baseline (left) and after system injection of C21 (right) – significant transients are highlighted in red. F) Group data on Ca 2+ transient frequency during baseline and C21 sessions for MCs and GCs (MCs: baseline n=274 cells, 7 mice, C21 n=257 cells, 7 mice; GCs: baseline n=484 cells, 3 mice, C21 n=412 cells, 3 mice; ***p<0.001 Mann-Whitney U test). G) Spatial tuning heatmaps for spatially tuned mossy cells in baseline and C21 sessions. Cells are sorted by the location of the peak of their spatial tuning curves. H) Group data showing proportion of spatially tuned cells in each mouse during baseline and C21 sessions (n=5 mice; *p<0.05 t-test, mean± s.e.m.). I) Group data showing MC place field width during baseline and C21 sessions (baseline, n=88 cells, 5 mice; C21, n=54 cells, 5 mice; mean± s.e.m.).

Article Snippet: For both hM3Dq and hM4Di experiments, mice received i.p. injections of DREADD agonist 21 (C21) (3 mg/kg; Tocris Cat No. 6422) 30 minutes before the start of imaging sessions.

Techniques: Imaging, In Vivo, Activation Assay, Fluorescence, Injection, MANN-WHITNEY

Journal: bioRxiv

Article Title: A novel, evolutionarily conserved inhibitory circuit selectively regulates dentate gyrus mossy cell function

doi: 10.1101/2025.07.09.663808

Figure Lengend Snippet: A) Example traces of GCaMP fluorescence traces from MCs (black, top), animal’s position in VR (gray, middle) and running velocity (green, bottom). B) Bar graph showing animal’s average running velocity during baseline and C21 sessions (n=5 mice; mean± s.e.m.). C) Bar graph showing total distance travelled during 12-minute imaging session under baseline and C21 conditions, mean± s.e.m.. D) Graph showing the activity-velocity correlation coefficient for MCs during baseline and C21 sessions (baseline, n=181 cells, 5 mice; C21, n = 150 cells, 5 mice; *p<0.05 Mann-Whitney U test). E) Histogram showing distribution of activity-velocity correlation lags for MCs during baseline and C21 sessions (baseline, n=181 cells, 5 mice; C21, n = 150 cells, 5 mice; *p<0.05 Kolmogorov-Smirnov test on distributions).

Article Snippet: For both hM3Dq and hM4Di experiments, mice received i.p. injections of DREADD agonist 21 (C21) (3 mg/kg; Tocris Cat No. 6422) 30 minutes before the start of imaging sessions.

Techniques: Fluorescence, Imaging, Activity Assay, MANN-WHITNEY

Journal: bioRxiv

Article Title: A novel, evolutionarily conserved inhibitory circuit selectively regulates dentate gyrus mossy cell function

doi: 10.1101/2025.07.09.663808

Figure Lengend Snippet: A) Images of familiar (left) and novel (right) virtual environments (top). Schematic of the layout and reward location for familiar and novel linear virtual environments (bottom). B) Schematic of viral injections for chemogenetic inhibition of VgluT3+ interneurons and imaging of MCs/GCs (left). Experimental timeline for chemogenetic inhibition during contextual switching paradigm (right). C) Group data showing Ca 2+ transient frequency during baseline and C21 sessions for MCs and GCs (MCs: baseline, n=312 cells, 5 mice, C21 n=271 cells, 5 mice; GCs: baseline n=407 cells, 2 mice, C21 n=550 cells, 2 mice; ***p<0.001, **p<0.01 Mann-Whitney U test). D) Spatial heatmaps of MCs with a significant place field in either the familiar or novel context during baseline and C21 sessions. Cells were sorted by the peak of their spatial tuning curve in the familiar context. E) Group data showing tuning curve correlations for within context (FF) and between context (FN) comparisons during baseline and C21 sessions (baseline n=167 cells, 3 mice; C21 n=155 cells, 3 mice; ***p<0.001 Kruskal-Wallis test). F) Graph showing the average magnitude of difference in correlation (1′ stability) between FF and FN comparisons for baseline and C21 sessions (baseline n=167 cells, 3 mice; C21 n=155 cells, 3 mice; *p<0.05 t-test; mean± s.e.m.). G) Plot showing proportion of MCs baseline and C21 conditions that exhibit a decrease, increase or no change in tuning curve correlation from FF to FN (baseline n=167 cells, 3 mice; C21 n=155 cells, 3 mice).

Article Snippet: For both hM3Dq and hM4Di experiments, mice received i.p. injections of DREADD agonist 21 (C21) (3 mg/kg; Tocris Cat No. 6422) 30 minutes before the start of imaging sessions.

Techniques: Inhibition, Imaging, MANN-WHITNEY

Journal: bioRxiv

Article Title: A novel, evolutionarily conserved inhibitory circuit selectively regulates dentate gyrus mossy cell function

doi: 10.1101/2025.07.09.663808

Figure Lengend Snippet: A) Example traces of GCaMP fluorescence traces from MCs (black, top), animal’s position in VR (gray, middle) and running velocity (green, bottom). Letters above position indicate environment type (Familiar - F or Novel - N) for each lap. B) Pie chart showing proportion of spatially tuned MCs in F, N or both environments during baseline and C21 conditions (baseline, n=243 cells, 3 mice; C21, n=201 cells, 3 mice). C) Average place field width for spatially tuned MCs during baseline and C21 conditions (baseline, n=243 cells, 3 mice; C21, n=201 cells, 3 mice). D) Graph showing activity-velocity correlation coefficient for MCs during baseline and C21 sessions. E) Histogram showing distribution of activity-velocity correlation lag during baseline and C21 sessions (baseline, n=243 cells, 3 mice; C21, n=201 cells, 3 mice)

Article Snippet: For both hM3Dq and hM4Di experiments, mice received i.p. injections of DREADD agonist 21 (C21) (3 mg/kg; Tocris Cat No. 6422) 30 minutes before the start of imaging sessions.

Techniques: Fluorescence, Activity Assay