Behavior Tests

Mice were on a 12-hour light/dark cycle and were given food and water ad libitum. Mice were between the ages of 16–20 weeks when behavioral testing commenced. All equipment was cleaned using Virkon. No method of randomization was utilized in the behavior studies.

The three-chambered social interaction paradigm was adapted from Yang et al. (21). The Morris water maze was conducted using the same paradigm as Chalermpalanupap et al. (22).

The San Diego Instruments (La Jolla, CA) SR-LAB startle response system was used to perform PPI. We used a two-day paradigm. On day one, we tested the ability of the mouse to startle to a series of increasing tones. On day two, we subjected each mouse through the prepulse inhibition paradigm. PPI was calculated as a percentage using the following equation: ((startle-startle.PP/startle))*100.

The assay was performed in a locomotor chamber (San Diego Instruments), which consisted of a plexiglass cage (48×25×22cm) containing corncob bedding that rested between an apparatus containing infrared beams. The mice were given an injection of either saline or amphetamine (2.5 or 7.5 mg/kg, i.p.), and post-injection ambulations were measured for 2 hours. All treatments were spread over 3 weeks and were counter-balanced such that not all of the mice received the same injection in a given week. For the 7.5mg/kg amphetamine dose, a subset of mice was video recorded between the 30–60 minute post-injection time point. These videos were scored for stereotypy using the criteria as described previously (23) by an experimenter blinded to genotype.

Details on paradigms for circadian rhythm, elevated plus maze, open field, marble burying, social interaction, prepulse inhibition, fear conditioning, and histology can be found in Supplemental Materials. Sample sizes of 8–16 mice per sex and genotype were used in agreement with existing literature.