The POA contains neurons that increase Fos expression in single-housed females following same-sex interactions.

(A) Schematic of experiment to measure Fos expression in group-housed and single-housed females following same-sex social interactions. (B) Total time spent engaged in resident-initiated social investigation for group-housed residents (teal) and single-housed residents (maroon). (C) Same as (B), for proportion of trials with resident-initiated mounting. (D) Same as (B), for total USVs recorded from pairs containing group-housed or single-housed residents. (E) Left-most image shows the location of the POA in a coronal brain section. Representative confocal images show Fos expression (green) in the POA of a group-housed female (left) and a single-housed female (right) following same-sex social interactions. Blue, Neurotrace. (F) Quantification of Fos-positive neurons is shown for the POA (left), the VMH (middle), and the caudolateral PAG (right) for group-housed and single-housed females. Open bars show data from females that did not engage in social interactions with novel females (baseline), and closed bars show data from females following social interactions with novel females (interaction). (G) Total time spent in resident-initiated interaction is plotted for 17-day single-housed (maroon) and re-group-housed females (teal) during same-sex interactions that occurred prior to isolation (day 0), following 3 days of isolation (day 3), and on the test day (day 17). (H) Same as (G), for total resident-initiated mounting time. (I) Same as (G), for total USVs. (J) Quantification of Fos-positive POA neurons is shown for 17-day single-housed females (maroon) and re-group-housed females (teal).

Effects of chemogenetic inhibition of POAsocial neurons on the social behaviors of single-housed female mice.

(A) Experimental timeline and viral strategy to chemogenetically inhibit the activity of POAsocial neurons in single-housed females. (B) Total time spent in resident-initiated social investigation is shown on saline and CNO days for 4 experimental groups: (red symbols) experimental females in which hM4Di is expressed in POAsocial neurons; (black symbols) control females in which GFP is expressed in POAsocial neurons; (brown symbols) control females in which hM4Di is expressed in ‘TRAPed’ AH neurons; (gray symbols) control females in which hM4Di is expressed in ‘TRAPed’ VMH neurons. (C) Same as (B), for proportion of trials with resident-initiated mounting. (D) Same as (B), for total USVs. (E) Total movement is plotted for females with hM4Di expressed in POAsocial neurons, on saline days vs. CNO days.

Effects of caspase-mediated ablation of POAsocial neurons on the social behaviors of single-housed female mice.

(A) Experimental timeline and viral strategy for caspase-mediated ablation of POAsocial neurons in single-housed females. (B) Total time spent in resident-initiated social investigation is shown pre- and post-4-OHT treatment for 2 experimental groups: (red symbols) experimental females in which caspase is expressed in POAsocial neurons; (black symbols) control females in which GFP is expressed in POAsocial neurons. (C) Same as (B), for proportion of trials with resident-initiated mounting. (D) Same as (B), for total USVs.

Effects of optogenetic activation of POAsocial neurons on the behaviors of group-housed female mice.

(A) Experimental timeline and viral strategy to optogenetically activate POAsocial neurons in group-housed females. (B) Mean total USVs produced during solo sessions shown for pre-laser periods and during laser stimulation periods for experimental females with ChR2 expressed in POAsocial neurons (red symbols; N = 9) and for control females with GFP expressed in POAsocial neurons (black symbols, N = 6). (C) Same as (B), for social sessions. (D) Spectrograms are shown from a representative POAsocial- ChR2 female to illustrate USVs that were elicited through optogenetic activation of POAsocial neurons in a solo session (top) and a social session (bottom). Blue bars indicate timing of laser stimulation. (E) Percentage of laser stimulations followed by a bout of social investigation, plotted for POAsocial-ChR2 and POAsocial-GFP females. (F) Probability of social investigation aligned with onset of laser stimulation is plotted over time for POAsocial-ChR2 and POAsocial-GFP females. (G) Mean duration of social investigation bouts that overlapped with laser stimulation vs. bouts that did not overlap with laser stimulation is shown for POAsocial-ChR2 and POAsocial-GFP females. Error bars in (E) show standard deviation and in (F) show standard error.

Experiments to test whether POA neurons regulate social behaviors of group-housed females.

(A) Experimental timeline and viral strategy to chemogenetically inhibit POA neurons that were TRAPed following same-sex social interactions in group-housed females. (B) Total time spent in resident-initiated social investigation is shown on saline and CNO days. (C) Same as (B), for proportion of trials with resident-initiated mounting. (D) Same as (B), for total USVs. (E) Experimental timeline and viral strategy to optogenetically activate POA neurons that were TRAPed following same-sex social interactions in group-housed females. (F) Mean total USVs produced during solo and social sessions shown for pre-laser periods and during laser stimulation periods. (G) Percentage of laser stimulations followed by a bout of social investigation, plotted for GH-TRAPed POA ChR2 females (N = 6) and POAsocial-GFP females (N = 6; same control group as in Figure 4). (H) Probability of social investigation following onset of laser stimulation is plotted over time for GH-TRAPed POA ChR2 and POAsocial-GFP females. (I) Experimental timeline and viral strategy to chemogenetically silence POA neurons in female mice, first while group-housed and a second time following single-housing. (J) Total time spent in resident-initiated social investigation is shown on saline and CNO days for group-housed tests. (K) Same as (J), for proportion of trials with resident-initiated mounting. (L) Same as (J), for total USVs. (M) Total time spent in resident-initiated social investigation is shown on saline and CNO days for single-housed tests. (N) Same as (M), for proportion of trials with resident-initiated mounting. (O) Same as (M), for total USVs. Error bars in (G) show standard deviation and in (H) show standard error.

Context-dependent differences in POA Fos expression and effects of chemogenetic inhibition of POAsocial neurons on the social behaviors of single-housed male mice.

(A) Total time spent in resident-initiated social investigation is shown for group-housed male residents (teal) and single-housed male residents (maroon) during interactions with either female visitors (left) or male visitors (right). (B) Same as (A), for proportion of trials with resident-initiated mounting. (C) Same as (A), for total USVs recorded from pairs containing group-housed or single-housed male residents. (D) Total number of Fos-positive POA neurons is shown for group-housed male residents (teal) and single-housed male residents (maroon) following interactions with female visitors (left) or male visitors (right). (E) Experimental timeline and viral strategy to chemogenetically inhibit the activity of POAsocial neurons in single-housed males. (F) Total time spent in resident-initiated social investigation is shown on saline and CNO days for experimental males in which hM4Di is expressed in POAsocial neurons (red symbols, N = 10) and control males in which GFP is expressed in POAsocial neurons (black symbols, N = 10). (G) Same as (F), for proportion of trials with resident-initiated mounting. (H) Same as (F), for total USVs.