[
International Worm Meeting,
2015]
We investigated whether associative memory can be formed through activation of sensory neurons with channelrhodopsin-2. Previously, a conditioning paradigm, using acidic solution as an unconditioned stimulus (US) and 1-propanol as a conditioned stimulus (CS), was shown to induce odor associations lasting as long as 24 hours. A tracking confocal microscope was used to design an aversive conditioning paradigm using optical stimulation in ASH neurons as a US and exposure to vapor of 100% 1-propanol as a CS. A closer investigation of the tracking data obtained from single individuals revealed that conditioned animals responded to 1-propanol with deeper bends than naive animals. To quantify this phenomenon we wrote a custom script for assessing the probability of observing the animal in that behavior. The learning index was calculated as the change in this probability before and after training. Wild type animals showed no predictable increase in learning index, while transgenic animals did. We then examined whether this behavior could persist for at least 6 hr. Two training regimens were used: with an inter-trial period (ITI) of 3 and 10 min. The first regimen was expected to induce short-term memory and the latter long-term memory. When conditioned animals were assayed 6 hr after training, the increase in learning index for 10-min ITI, but not for 3-min ITI was observed. Our findings demonstrate that olfactory conditioning can, at least in part, be achieved using optogenetic stimulation to induce a long-term associative memory.