Figure 4

The effect of lesion in either of the two mPFC hemispheres on social defeat stress.

(a) Regional extent of electrolytic lesion in a slice. (b) Timeline of social defeat stress after unilateral lesion of the mPFC. Interaction ratio (±social target) was measured in control and socially defeated mice without or with right (R) or left (L) mPFC lesion. Grey dots, non-stressed mice; red dots, susceptible mice; blue dots, resilient mice. Non-stressed controls, no lesion, no social defeat, n = 14; social defeat without lesion, n = 14; social defeat with right (R) lesion, n=10; social defeat with left (L) lesion, n = 12. Non-stressed vs. social defeat without lesion, t₂₆= 2.522, *P = 0.018, t-test; social defeat with right lesion vs. social defeat with left lesion, t₂₀= 3.166, *P = 0.005, t-test. Data are presented as means ± s.e.m. (c) Model of mPFC function in the regulation of social behavior in stressed mice and stress acquisition. Chronic social defeat stress induces an increase in the right mPFC, while the firing rate of the left mPFC changes differentially according to social behavior. In the susceptible group, low activity in the left mPFC results in expression of social avoidance. However, increased activity of the left mPFC in resilient mice reinstates social interactions to normal levels. Unilateral lesion of the mPFC before stress affects acquisition of stress. Right mPFC lesion prevents perception of stress, manifesting as stress resistance. On the other hand, lesion of the left mPFC blocks the expression of stress resilience, causing mice to show low sociability.