Fig. 2
Object location memory is facilitated by optogenetic induction of long-term potentiation of SOM-IN excitatory afferents. A Left: schematic of cannulation with representative image of hChR2-mCherry expression of the AAV2/9-CaMKIIa-hChR2(E123T/T159C)-mCherry in dorsal CA1 hippocampus of SOM-Cre-EYFP mice. Right: diagram of behavioral testing sequence (open field and object location memory task). B Experimental protocol of the object location memory task with optogenetic induction of PC-SOM synapse LTP (TBSopto) 30 min before the training session. C–G Color coding of groups is as follows. Grey: control mice without TBSopto, n = 10 mice. Blue: mice with TBSopto, n = 14 mice. Dark colors = training, light colors = test. C Representative path traveled during training and test sessions. D Left: graph of total exploration time of objects during the training session, showing no difference between groups (t-test). Middle: graph of the percentage of time spent exploring the mobile object during training and test sessions, showing no difference during training sessions, but increased exploration time during test session for mice that received TBSopto before training, relative to controls. Two-way repeated measures ANOVA, Bonferroni pairwise multiple comparisons. Right: graph of preference ratio showing facilitation of object location memory for mice that received TBSopto relative to control mice without TBSopto (Mann-Witney Rank Sum Test). ns p > 0.05, *p < 0.05, ***p < 0.005. E Open field. Left: zone separations used for analysis. Right: representative path traveled during the open field test for control and mice receiving TBSopto. F Graphs showing similar time spent in periphery (left) or center (middle), and ratio of time in center/periphery (right), indicating normal anxiety in both groups. Mann-Witney Rank Sum Tests, ns p > 0.05. G Graphs showing similar total distance traveled (left) and zone transitions (right) in both groups, indicating normal locomotion. Total distance: Mann-Witney Rank Sum Test. Zone transitions: t-test. ns p > 0.05