Figure 1.
Paradigm for monitoring social preference during reliable induction of self-grooming
(A) A coronal section across the ventral striatum showing in situ hybridization of Cre mRNA in a D3-Cre mouse. Image credit: Allen Institute (Allen Mouse Brain Connectivity Atlas: http://connectivity.brain-map.org/transgenic/experiment/304166273). Scale bar = 1 mm. Inset: an enlarged view of dotted rectangle area in the left panel. Arrow denotes the IC. PC, piriform cortex. NAc, nucleus accumbens. OT, olfactory tubercle. IC, islands of Calleja.
(B) D3-ChR2 neurons are densely packed in the IC. Left, a representative image (coronal section) showing the IC and the optical fiber tract (upper), as well as the firing of an IC D3-ChR2 neuron upon laser stimulation at 20 Hz (lower). Scale bar = 200 μm. Right, an enlarged image of the IC (dotted rectangle area in the left panel). Scale bar = 20 μm.
(C) Coronal brain panels showing optical fiber placements in D3-Cre/ChR2 mice.
(D) Upper, schematic showing the behavioral strategy in the three-chamber apparatus. Blue light stimulation of OT D3-ChR2 neurons induced robust self-grooming (More grooming) while green light with the same stimulation parameters produced less (Less grooming). Lower, schematic depicting experimental timeline of the test. Ten min test for each observer mouse (Mob) with a 5 min interval between two consecutive mice.
(E and F) Comparison of total grooming time in 10 s (E) and 10 min (F) between spontaneous and light-stimulation conditions in an entire session. Data are shown as the mean ± SEM. One-way ANOVA test with post hoc Tukey’s multiple comparison test (E) and two-tailed unpaired Student’s t test in (F). ∗∗∗∗ or #, p < 0.0001. Raw data are included in Table S1 and results of statistical analyses are included in Table S2.