Integrating Optogenetics and Fear Conditioning

Data shown are representative results from 4 OMP-ChIEF mice and 4 wild type mice (all males, 6-7 weeks old). Experimental animals were prepared by the surgical implantation of the optical fiber in the mouse olfactory bulb. A behavioral training commenced using a modified 'two-arms maze,' derived from the 'Y' maze design. Two arms of the maze are marked as light zone and safe zone. During training, light stimulation paired with mild foot shocks was applied as the mice fully entered into the light zone. The Safe zone remained accessible to the mice to avoid the foot shocks. The light stimulation involved ten 50 ms pulses with 150 ms intervals, triggered externally by a Master-8 timer.<b>Light zone aversion assessment task</b>To ensure unbiased testing conditions, the electric grid shock floor was removed from the "two-arms maze," eliminating foot shock exposure during the testing sessions. Mouse activity within the maze was evaluated in blocks of three trials, each lasting 15 minutes. Movement within the "two-arms maze" was tracked using Any-maze video tracking software (Stoelting, IL, USA) to calculate time spent in each arm. Additionally, heatmaps were generated for every trial, visually displaying the duration spent by mice in distinct areas of the arena. Color ranges within the heatmap represented varying durations, with blue indicating the shortest and red indicating the longest time spent in specific regions.<br>