Cory Knox - Dr. Liston - WK6

 This week was again filled with mouse surgeries as Shane and I push to complete AAV-injected, fiber optic implantation samples in the female and male mouse cohorts. Each mouse requires an AAV injection to the prefrontal cortex of either CamKII-GFP (Control group) or CamKII-Chronos (Stimulus group), followed by a fiber optic implant to the injection site and a head plate attachment to the skull for future head-fixed behavior assays. We were able to complete 20 surgeries, while also performing the first few days of novelty-induced hypophagia (NIH) on a separate mouse cohort. 

The first few days of NIH involve numerous days of handling to allow the mouse to adjust to the experimenter. Handling is used to minimize unintentional stress artifacts by familiarizing the mouse with the handler. Naturally, any behavioral assay will possess handler stress artifacts due to the natural stress that comes with animal work, but our goal is to at least mitigate the size of said artifact. The following days the mice were fed diluted sweetened condensed milk via dropper bottle with free-roaming cage behavior. This is considered the training period of NIH. The mice will adjust to the presence of a reward and begin to associate the bottle as another part of its environment, that being the home cage. The training period covers several days as well to ensure the mice adapt. The week concluded with the mice receiving their first session of stimulus via fiber optic probe. This involves attaching the fiber optic plug that lies outside of the skull to the laser source. The laser is then turned on at a specified pulse rate and light stimulus is delivered to the brain at the target site. The previously injected AAV-Chronos is then activated by the laser due to its excitation wavelength, causing increased, targeted neuronal activity. The stimulus period covers several days as well.

Next week, we will continue surgeries for other behavioral assays, while concluding the NIH behavioral timeline.