Conditional ablation and recovery of forebrain neurogenesis in the mouse

Forebrain neurogenesis persists throughout life in the rodent subventricular zone (SVZ) and hippocampal dentate gyrus (DG). Several strategies have been employed to eliminate adult neurogenesis and thereby determine whether depleting adult-born neurons disrupts specific brain functions, but some approaches do not specifically target neural progenitors. We have developed a transgenic mouse line to reversibly ablate adult neural stem cells and suppress neurogenesis. The nestin-tk mouse expresses herpes simplex virus thymidine kinase (tk) under the control of the nestin 2nd intronic enhancer, which drives expression in neural progenitors. Administration of ganciclovir (GCV) kills actively dividing cells expressing this transgene. We found that peripheral GCV administration suppressed SVZ-olfactory bulb and DG neurogenesis within 2 weeks but caused systemic toxicity. Intracerebroventricular GCV infusion for 28 days nearly completely depleted proliferating cells and immature neurons in both the SVZ and DG without systemic toxicity. Reversibility of the effects after prolonged GCV infusion was slow and partial. Neurogenesis did not recover 2 weeks after cessation of GCV administration, but showed limited recovery 6 weeks after GCV that differed between the SVZ and DG. Suppression of neurogenesis did not inhibit antidepressant responsiveness of mice in the tail suspension test. These findings indicate that SVZ and DG neural stem cells differ in their capacity for repopulation, and that adult-born neurons are not required for antidepressant responses in a common behavioral test of antidepressant efficacy. The nestin-tk mouse should be useful for studying how reversible depletion of adult neurogenesis influences neurophysiology, other behaviors, and neural progenitor dynamics. J. Comp. Neurol. 514:567–582, 2009. © 2009 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62155/1/22052_ftp.pd

Brand origin recognition accuracy: its antecedents and consumers’ cognitive limitations

An ever-growing literature has reported consumer bias toward national origins of products, and has explored factors that moderate such bias. Researchers have assumed, if only tacitly, that consumers are knowledgeable of brand origins, and that this knowledge is a significant influence that drives judgments of product quality, brand attitudes, and choice behavior in the marketplace. Using categorization theory and attribute diagnosticity as the theoretical foundation, our research reveals that consumers actually have only modest knowledge of the national origins of brands, and that American consumers’ proficiency at recognizing foreign brand origins is predicted by variables such as socioeconomic status, past international travel, foreign language skills, and gender. In the second of two studies, we determined that brand origin recognition is based largely on consumers’ associations of brand names with languages that suggest country origins. These studies ultimately lead us to conclude that past research has inflated the influence that country of origin information has on consumers’ product judgments and behavior and its importance in managerial and public policy decisions. Journal of International Business Studies (2005) 36, 379–397. doi:10.1057/palgrave.jibs.8400145