The great American philosopher Alicia Keys once declared that “Big lights will inspire you” on a track with Jay-Z.
It’s this sentiment that I’ll be spending my summer trying to extrapolate to my mice. See, my project involves optogenetic stimulation of the brain. Optogenetics is a brain stimulation technique that relies on light. Basically, a surgeon puts some implants in a specific region of the mouse brain, we hook up the mice to some optic fibers, and then we use light on that brain region to stimulate it.
Optogenetics is a powerful technique because it allows us to pinpoint certain regions and see how behavior is altered by either activation or inhibition of those regions. In my project, we’re trying to see how activation and inhibition in the prefrontal cortex affects operant learning (learning to perform a task to obtain a reward). To test this, I’ve spent some time training mice to press a lever under different reward schedules. First, they learned that one press of a small lever leads to the release of one pellet of food. After 3 days of that schedule, I ramped it up to 5 lever presses for one pellet of food, and then finally to 10 lever presses for one pellet of food. The first day, they’ll take two hours and maybe press the lever 20 times or so, but within 2 days of training, they’ll press it 50 times in less than 10 minutes. It’s just like us humans— if we’re hungry and want food, we’ll figure out what it takes to get it.
After the first 9 days of training and eagerness to see the results of the experiment, I initialized the optogenetic stimulation for the first time on Saturday. The operant conditioning chambers in the lab are each equipped with motion sensors to track when the mice put their little heads in the feeding area and each box is connected to two computers that control the illumination and track how many times each mouse presses the lever to obtain a food pellet. Right now, I’m focused on collecting data and processing it so that I can start to make graphs for the analysis this upcoming week.
If I’m able to observe a significant change in the lever pressing behavior in response to illumination, we could develop a more detailed model of the operant learning pathway that’s being studied in other projects in the lab as well. The results from Saturday and Sunday will be my first optogenetic results of the summer, and I’m looking forward to seeing if the data I gathered can implicate the implanted brain region into the operant learning pathway.