Regulation of Fear Behavior by Microcircuits within the Mouse Amygdala
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Abstract
Background: The amygdala is a core structure in the mammalian brain that processes emotion and memory. Its complex neuronal composition and intricate microcircuit mechanisms play key roles in behaviors such as fear, anxiety, and reward. The diversity of neuronal types and the dynamics of these microcircuits provide the neural foundation for the encoding and extinction of fear memories.
Aim: This is a retrospective review article summarizing recent research on the amygdala and fear behavior in mice, which is of significant importance in helping people to comprehensively understand and recognize that the amygdala is the core regulator of fear behavior.
Methodology: An extensive and systematic search of electronic databases (Medline, PubMed, Web of Science) using keywords related to the amygdala and the technologies involved in the study such as “mouse amygdala,” “basolateral amygdala (BLA),” “central amygdala (CeA),” “fear extinction,” “fear learning,” and “microcircuits.” Articles meeting the selection criteria were included as candidate references.
Results: By integrating recent findings from optogenetics, chemogenetics, and single-cell sequencing, this review reveals the interactions between glutamatergic projection neurons and GABAergic interneurons in the amygdala, the functional division between subnuclei, and the neural basis of cross-brain area coordination. Additionally, it discusses the technical challenges in amygdala research and future directions, providing theoretical support for understanding the pathophysiology of emotional disorders.
Conclusion: The amygdala is intimately linked to emotional health, playing a critical role in understanding the mechanisms underlying the development of psychiatric disorders such as anxiety, depression, addiction, and post-traumatic stress disorder (PTSD). Despite advances in methodologies such as in vivo calcium imaging, neural circuit tracing, and electrophysiological techniques, which are progressively uncovering the underlying mechanisms of amygdalar regulation of emotional behaviors, the intrinsic microcircuitry of the amygdala remains highly complex. Significant gaps persist, necessitating further exploration and refinement to elucidate unresolved aspects of its functional architecture and behavioral modulation.
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