Spatial, temporal, and circuit-specific activation patterns of basolateral amygdala projection neurons during stress
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2023-07
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Abstract
In humans and rodents, the amygdala is rapidly activated by stress and hyperactivated in conditions of pathological stress or trauma. However, there is a striking lack of information of the anatomical specificity of amygdala subregions and circuits explicitly activated by stress, and of its role in governing typical responses to stress such as hypothalamic-pituitary-adrenal (HPA) axis activation. The overarching aim of this thesis was to conduct a systematic investigation of the spatial, temporal, and circuit-specific activation patterns of basolateral amygdala (BLA) projection neurons during exposure to acute stress. Additionally, we explicitly tested the role of the BLA in activation of the HPA axis, as this remains a poorly understood process. Chapter 1 describes how the BLA is anatomically well-situated for cognitive evaluation of emotional stimuli and describes the role of the BLA in diverse behavioural and physiological processes via efferent projections to many different brain structures. Chapter 2 identifies a common BLA subregion that is responsive to stressful stimuli, albeit with distinct temporal activation patterns, and which bidirectionally influences HPA axis activity. Chapter 3 maps the topographical distribution of six different populations of projection neurons throughout the BLA, and demonstrates that, although widely activated by stress exposure, inhibition of isolated populations does not influence HPA axis activity. Chapter 4 investigates the topographical distribution and stress-induced activation of BLA neurons expressing corticotropin-releasing hormone receptor type I (CRHR1), which, just like discrete circuits, does not influence HPA axis activity on its own. Together, this emphasizes the heterogeneity of BLA projection populations, while providing evidence that a large, diverse population of BLA projection neurons are activated by exposure to acute psychological stress.
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Aukema, R. (2023). Spatial, temporal, and circuit-specific activation patterns of basolateral amygdala projection neurons during stress (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.