Behavioral sensitization to cocaine
Figure 1B Male, aged 6-8 weeks old at the time of virus injections. The experimental group of CLEgr2+ inhibition comprised of (n=9) Egr2-Cre male mice, aged 6-8 weeks, which were bilaterally injected with 100nl AAVdj-CAG-DIO-GPE2 (Kir2.1) to the claustrum, (LM: ±2.8mm, RC: 1mm, DV: -3.7). As a control group, (n=6) Egr2-Cre male mice, 6-8 weeks old, were injected with 100nl AAVdj-CAG-DIO-eGFP to the same coordinates. Animals were randomly assigned to control and experimental group. Before the start of an experiment, mice were acclimated to the animal facility for 5 days, followed by 3 days of experimenter handling once daily. Animals were then subjected to three days of intraperitoneal (IP) saline injections (250 μl/injection) and transferred to a video-recorded open field arena for 15 minutes(as in(AU-Turm et al., 2014; Mukherjee et al., 2018)). Mice received cocaine (IP, 20 mg/kg freshly dissolved in 0.9% saline to 2 mg/ml, injected at a volume of 10 ml/kg), transferred to the open field arena for 15 minutes to measure locomotor behavior. Locomotor activity was assessed in sound- and light- attenuated open-field chambers. Mice were placed individually in a clear, dimly lit Plexiglas box (30×30×30 cm) immediately after the IP injection of saline or cocaine. Activity was monitored with an overhead video camera for a total of 15 minutes while the mice were in the open field chamber using Ethovision software (Noldus, Wageningen, Netherlands). Cocaine was purchased from the pharmacy at Hadassah Hospital, Jerusalem. No experimental mice were excluded from analysis.