High-Frequency Local Field Potential Oscillations May Modulate Aggressive Behaviors in Mice

SIMPLE SUMMARY: We investigated the dynamic patterns of neural activities related to aggressive behavior in male CD-1 mice. Our objective was to understand how rearing patterns shape aggressive behavior and which neural activities may engage in mediating aggressive behaviors in mice. We found that (1) socially isolated mice exhibited more aggression compared with cohousing mice; (2) cohousing mice exhibited significantly greater beta activities but substantially smaller gamma activities compared with the socially isolated mice; (3) gamma activities during attacks were significantly greater than that before attacks in the right ventromedial hypothalamus (VMH) of socially isolated mice. These findings suggest that rearing patterns could shape aggressive behaviors in mice and that the high frequency neural activities (beta and gamma activities) may engage in mediating these behaviors. ABSTRACT: Aggressive behavior is one of congenital social behaviors in many species, which could be promoted by social neglect or isolation in the early stages of life. Many brain regions including the medial prefrontal cortex (mPFC), medial amygdala (MeA) and ventromedial hypothalamus (VMH) are demonstrated to relate to aggressive behavior; however, the dynamic patterns of neural activities during the occurrence of this behavior remain unclear. In this study, 21-day-old male CD-1 mice were reared in social isolation conditions and cohousing conditions for two weeks. Aggressive behaviors of each subject were estimated by the resident–intruder test. Simultaneously, the local field potentials of mPFC, MeA and VMH were recorded for exploring differences in the relative power spectra of different oscillations when aggressive behaviors occurred. The results showed that the following: (1) Compared with the cohousing mice, the socially isolated mice exhibited more aggression. (2) Regardless of “time condition” (pre-, during- and post- attack), the relative power spectra of beta band in the cohousing mice were significantly greater than those in the socially isolated mice, and inversely, the relative power spectra of gamma band in the cohousing mice were significantly smaller than those in the socially isolated mice. (3) The bilateral mPFC exhibited significantly smaller beta power spectra but greater gamma power spectra compared with other brain areas regardless of rearing patterns. (4) For the right VMH of the socially isolated mice, the relative power spectra of the gamma band during attacks were significantly greater than those before attack. These results suggest that aggressive behaviors in mice could be shaped by rearing patterns and that high-frequency oscillations (beta and gamma bands) may engage in mediating aggressive behaviors in mice.