Fig. 2
From: Artificial association of memory events by optogenetic stimulation of hippocampal CA3 cell ensembles
Optogenetic stimulation of cell ensembles in CA3 associates distinct events. a Diagram showing the cannula placement and activity-dependent labeling of neurons in c-fos::tTA/KA1::Cre double transgenic mice with the AAV system. Gray and white triangles represent loxP and lox2272 sequences, respectively. b Diagram showing the experimental scheme. After bilateral CA3 infection with the AAV, the c-fos::tTA/KA1::Cre double transgenic mice were exposed to context A and CFC in context B in OFF Dox condition. One day after CFC, the CA3 regions of the laser ON group (n = 12) were optically stimulated, whereas the laser OFF group (n = 10) received no optical stimulation. Mice were tested for their freezing responses in contexts A, B, and C on 1, 2, and 3 days after the optical stimulation, respectively. Graphs showing freezing responses during pre-exposure to context A (unpaired Student’s t test, t20 = 1.255, p = 0.2239) (c), pre-foot shock session during CFC in context B (unpaired Student’s t test, t20 = 0.6455, p = 0.5259) (d), and during and after foot shock session of CFC in context B (Welch’s t test; t12.62 = 0.2795, p = 0.7844) (e). Results of the tests in context A (Welch’s t test; t16.22 = 3.809, p = 0.0015) (f), context B (unpaired Student’s t test; t20 = 0.8214, p = 0.4211) (g), and the novel context C (unpaired Student’s t test; t20 = 0.8279, p = 0.4175) (h). **p < 0.01; n.s., no significant difference between the two groups; error bars are the means ± SEMs