Impact of Stress on Gamma Oscillations in the Rat Nucleus Accumbens During Spontaneous Social Interaction

Abstract

Alteration in social behavior is one of the most debilitating symptoms of major depression, a stress related mental illness. Social behavior is modulated by the reward system, and gamma oscillations in the nucleus accumbens (NAc) seem to be associated with reward processing. In this scenario, the role of gamma oscillations in depression remains unknown. We hypothesized that gamma oscillations in the rat NAc are sensitive to the effects of social distress. One group of male Sprague-Dawley rats were exposed to chronic social defeat stress (CSDS) while the other group was left undisturbed (control group). Afterward, a microelectrode array was implanted in the NAc of all animals. Local field potential (LFP) activity was acquired using a wireless recording system. Each implanted rat was placed in an open field chamber for a non-social interaction condition, followed by introducing another unfamiliar rat, creating a social interaction condition, where the implanted rat interacted freely and continuously with the unfamiliar conspecific in a natural-like manner (see Supplementary Videos ). We found that the high-gamma band power in the NAc of non-stressed rats was higher during the social interaction compared to a non-social interaction condition. Conversely, we did not find significant differences at this level in the stressed rats when comparing the social interaction- and non-social interaction condition. These findings suggest that high-gamma oscillations in the NAc are involved in social behavior. Furthermore, alterations at this level could be an electrophysiological signature of the effect of chronic social stress on reward processing.

Extracellular matrix remodeling with stress and depression: Studies in human, rodent and zebrafish models

“…Gamma oscillations have also been monitored during social interactions in the nucleus accumbens of rats that were exposed to chronic social defeat. This study observed a significant reduction of power increase in high gamma activity (61–90 Hz) for stress‐exposed rats as compared to the non‐stressed group (Iturra‐Mena et al., 2019).…”

Theta-Range Oscillations in Stress-Induced Mental Disorders as an Oscillotherapeutic Target

“…Conveniently, most of the CAD files designed by developers for multichannel recordings are now available from cloud-based repositories, such as Mendeley data, and laboratory websites, which enables researchers to freely create these devices. Furthermore, wireless recording systems are recently available ( Zuo et al, 2012 ; Martinez et al, 2018 ; Iturra-Mena et al, 2019 ), which are especially useful for stress research because they reduce the physical stress of animals.…”

Operant conditioning deficits and modified local field potential activities in parvalbumin-deficient mice

“…This would increase the inhibitory activity of the PV-FSI on the medium spiny neurons (MSN), which would generate oscillations in -frequency range. Conversely, stress-induced rats by social interaction with unfamiliar conspecific exhibited decreased oscillations in the NAc, as a consequence of a decreasing in the levels of DA in the NAc which provoked a decrease in the activity of the PV-FSI 54 , 55 . This might also suggest that PVKO mice are likely to be characterized by a reduced sensitivity to reward state, but our baseline condition could not reveal it because mice were left alone during LFP recordings.…”