Neuronal Representation of Social Information in the Medial Amygdala of Awake Behaving Mice

Abstract

SUMMARY The medial amygdala (MeA) plays a critical role in processing species- and sex-specific signals that trigger social and defensive behaviors. However, the principles by which this deep brain structure encodes social information is poorly understood. We used a miniature microscope to image the Ca2+ dynamics of large neural ensembles in awake behaving mice and tracked the responses of MeA neurons over several months. These recordings revealed spatially intermingled subsets of MeA neurons with distinct temporal dynamics. The encoding of social information in the MeA differed between males and females and relied on information from both individual cells and neuronal populations. By performing long-term Ca2+ imaging across different social contexts, we found that sexual experience triggers lasting and sex-specific changes in MeA activity, which, in males, involve signaling by oxytocin. These findings reveal basic principles underlying the brain’s representation of social information and its modulation by intrinsic and extrinsic factors.

Observational fear behavior in rodents as a model for empathy

“…The authors further showed that the Nrxn1‐ dependent LA‐MeA circuit is required for associating the affective content of social cues (distress of conspecific) with the predictive cues of the external environment and LA‐MeA strength was correlated with the level of freezing in social fear conditioning . Consistently, a recent study supports that the distinct MeA neuronal populations are implicated in encoding of social and defensive information in mice …”

Miniscope GRIN Lens System for Calcium Imaging of Neuronal Activity from Deep Brain Structures in Behaving Animals

“…For brain regions such as dorsal striatum (Barbera et al, 2016), prelimbic cortex (Pinto & Dan, 2015) and hippocampus (Ziv et al, 2013), a 1mm diameter GRIN lens can be used to increase the field of view. For deeper regions, such as amygdala (Li et al, 2017), hypothalamus (Jennings et al, 2015), nucleus accumbens, etc., a 0.5 mm diameter GRIN lens will be a better choice to minimize brain tissue damage from lens implantation. To implant a 1mm diameter GRIN lens, tissue removal is necessary to make room for the lens, whereas a 0.5mm diameter GRIN lens can be directly implanted into the brain after a leading track is made with a blunt-end needle.…”

Sex differences in main olfactory system pathways involved in psychosexual function

“…107 A picture emerges that the Me contains subpopulations of specific neurons identifiable by sexually dimorphic expression of genes that integrate olfactory inputs to drive specific behaviors. 107 A picture emerges that the Me contains subpopulations of specific neurons identifiable by sexually dimorphic expression of genes that integrate olfactory inputs to drive specific behaviors.…”