Fig. 2

SOM-IN activity correlates with reward-related position in maze during training but not in SOM-Rptor-KO mice. A From left to right: (left most) fluorescence image of GCaMP6f expression in hippocampal SOM-INs of a representative control animal without cranial surgery; scale bar 100 µm. (Middle left) Diagram showing cranial window position above dorsal hippocampus. (Middle right) Fluorescent image from representative animal after behavior experiments showing neocortical tissue removed for cranial window placement and hippocampal SOM-IN GCaMP6f expression; scale bar 100 µm. (Rightmost) High power confocal images of in vivo field of view with SOM-INs expressing GCaMP6f; scale bar 20 µm. B Example of simultaneous measurements (from top to bottom) of maze position, animal speed, and Ca²⁺ responses (colored traces) from 6 SOM-INs during a training session. C Ca²⁺ responses of a representative SOM-IN at start (session 3; left) and end (session 16; right) of training. Top: mean Ca²⁺ responses (grey) and speed (red) as function of position for all trials with reward zone indicated in green. Bottom: color-coded Ca²⁺ activity in each trial of the session, showing activity correlated with position at the end of training. D Correlation of Ca²⁺ responses with position across laps (place correlation) at sessions 3 and 16, showing place correlation developed with training. For each left: place correlation matrix of all paired laps. For each right: distribution of r values (blue), mean r (red) versus r distribution obtained by shuffling position measures (gray). E Correlation of Ca²⁺ responses with animal speed is present at sessions 3 and 16. For each left: Ca²⁺ responses as function of speed, blue lines correspond to correlation for each trial and red line to mean. For each right: distribution of r values (blue), mean r (red). F Similar representation of Ca²⁺ responses correlation with animal acceleration that is absent at sessions 3 and 16. G Mean place correlation for all SOM-INs showing the increase in place correlation over training sessions in control mice but not in SOM-Rptor-KO mice. H, I Mean correlation of Ca²⁺ activity with speed (H) and acceleration (I) for all SOM-INs did not change with training. J Mean place correlation as a function of mean learning index over training sessions for all animals, showing correlation in control but not SOM-Rptor-KO mice. Note that learning index measures are different from those of Fig. 1K because here only mice with calcium imaging are included in the analysis. Details of statistical tests provided in Additional file 5: Table S1. *p < 0.05, **p < 0.01, ***p < 0.001, ns not significant