Figure 5.

Figure 5.

Glycinergic modulation of the escape and swim circuits is socially regulated. A–C, Probability of startle escape response before (control) and after Strychnine injections for communals, dominants, and subordinates, respectively. Asterisks denote statistical difference between control and experimental condition at the specified decibel level. We performed repeated measures of ANOVA (within-subject factors as treatment and decibel) followed by one-sample two-sided t test for the post hoc test at each decibel. In communals, there was a marginal main effect of treatment (F_(1,9) = 3.71, p = 8.62e-2), but there were significant main effect of decibel (F_(1.5,13.3) = 1.53e+2, p = 8.62e-2) and significant effect of treatment*decibel interaction (F_(2.2,19.7) = 3.71, p = 3.96e-2). Strychnine marginally increased startle response for communal animals. In particular, post hoc test showed that there was a significant difference of the startle responses at 85 dB (t₍₉₎ = 2.51, p = 3.32e-2). In dominants, there were significant main effect of treatment (F_(1,11) = 1.44e+1, p = 2.96e-3), decibel (F_(1.9,20.4) = 7.72e+1, p = 5.00e-10), and significant effect of treatment*decibel interaction (F_(2.4,25.9) = 4.04, p = 2.45e-2). Strychnine significantly increased the startle response for dominant animals. In particular, post hoc test showed that there was a marginal difference of the startle responses at 75 dB (t₍₁₁₎ = 1.82, p = 9.60e-2), but there were significant differences at 80 dB (t₍₁₁₎ = 2.65, p = 2.24e-2) and 85 dB (t₍₁₁₎ = 2.95, p = 1.33e-2). In subordinates, there was a significant main effect of decibel (F_(2.0,21.7) = 5.07e+1, p = 6.99e-9), but no effect of treatment (F_(1,11) = 1.60, p > 0.05) and no effect of treatment*decibel interaction (F_(2.3,25.8) = 1.28, p > 0.05). D–F, One-minute recording of far field-potentials of spontaneous swimming activity before (control) and after strychnine injections for communal, dominants, and subordinates, respectively, along with respective average swimming frequency for all animals tested (horizontal dashed lines set arbitrarily to compare swim frequencies across experimental conditions). G, Box and whiskers plots of the average number of swim bursts per 1 min for each social phenotype. Box plot parameters are defined in Figure 1G. We performed the repeated measures of ANOVA (within-subject factor as treatment). In communals (n = 10) and dominants (n = 10), there were significant effects of treatment (strychnine; F_(1,9) = 6.06, p = 3.61e-2 for communals; F_(1,9) = 1.06e+1, p = 9.88e-3 for dominants). In subordinates (n = 10), there was no effect of treatment (strychnine; F_(1,9) = 8.76e-3, p > 0.05). H, I, Simulated response of dominant-like (H) and subordinate-like (I) models of escape circuit to positive current injections in the sensory input with/without (ON/OFF) GlyR, thus, mimicking GlyR antagonism (gGL→M=0).