PHD, Kent State University, 2016, College of Arts and Sciences / Department of Psychological Sciences
Anxiety disorders are the most common mental disorder with nearly 30% of individuals meeting criteria for an anxiety disorder over the course of their lifetime, generating significant personal, financial and emotional burden. Additionally, women are 60% more likely than men to be diagnosed with an anxiety disorder, such as PTSD. Inappropriate fear that occurs in normally safe environments, or fear generalization, is a key symptom of many anxiety disorders. The current set experiments explores sex differences in the generalization of fear and identifies mechanisms by which estradiol affects fear generalization. Results demonstrate that females generalize fear at a faster rate than males, and this process is driven, in part, by estradiol. However, in males, estradiol acts to attenuate generalization rather than to induce generalization. In fact, testosterone also attenuates generalization in gonadectomized males and does so through conversion into estradiol via aromatase. Estradiol impacts generalization through effects on memory retrieval rather than memory acquisition/consolidation. In females, estradiol acts through activation of cytosolic ERß within the dorsal CA1 region of the hippocampus and the anterior cingulate cortex (ACC), but not the ventral CA1 region of the hippocampus. Finally, estradiol-induced generalization in females appears to be a result of augmented glutamatergic signaling within the dorsal CA1 and ACC; blocking glutamate receptor activation attenuates estradiol-induced generalization. These mechanisms can help explain the discrepancies in prevalence rates for anxiety disorders between males and females, and are also crucial for development of more effective, and potentially sex-specific, treatments for anxiety disorders such as PTSD.
Committee: Aaron Jasnow Ph.D (Advisor); David Riccio Ph.D (Advisor); Stephen Fountain Ph.D (Committee Member); Karin Coifman Ph.D (Committee Member); John Johnson Ph.D (Committee Member); Heather Caldwell Ph.D (Committee Chair)
Subjects: Animals; Behavioral Psychology; Biology; Endocrinology; Experimental Psychology; Neurobiology; Pharmacology