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Seasonal plasticity of physiological systems, brain, and behavior

Pyter, Leah M.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1141319505

Abstract Details

2006, Doctor of Philosophy, Ohio State University, Neuroscience.
Seasonal adaptations have evolved in animals and are believed to promote survival and reproduction through yearly changes in the environment. These seasonal responses are physiological, morphological, and behavioral and are coordinated by day length (photoperiod) information in non-tropical rodents. In the laboratory, short days promote a winter phenotype, whereas long days promote a summer phenotype. This dissertation was designed to examine the effects of photoperiod on adult plasticity of physiology, brain, and behavior in male white-footed mice (Peromyscus leucopus) that may represent seasonal adaptations to the changing environment. Recent evidence suggests that significant plasticity occurs in adult systems including the central nervous system. The first studies examined the effects of photoperiod on angiogenesis in the periphery and the brain. Short days altered expression of angiogenesis genes in testes and brain and decreased cerebral blood flow compared with long days. The next set of studies was based on the finding that short days decreased brain mass and impaired spatial learning and memory compared with long days. The hippocampus is involved in spatial learning and memory and is one of the few brain regions associated with significant adult plasticity. Short days decreased hippocampal volume, altered hippocampal dendritic spine density, modified the effects of learning experience on neurogenesis, and dampened long-term potentiation compared with long days. Photoperiod alters concentrations of various hormones, some of which affect the hippocampal morphology and function. Testosterone reversed the short-day impairment of spatial learning and memory indirectly of hippocampal steroid receptors, but did not affect long-day performance. Corticosterone altered spatial learning and memory depending on photoperiod and duration of exposure and short days altered the hypothalamic-pituitary-adrenal axis compared with long days. The effects of photoperiod on the other brain region characterized by significant adult plasticity, the olfactory bulbs, and olfaction was examined. Neurogenesis increased in the caudal olfactory bulbs of short-day mice. Finally, I tested the effects of photoperiod and testosterone on depressive- or anxiety-like behaviors and observed few differences. Taken together, photoperiod appears to coordinate adult plasticity within the endocrine and nervous system that result in behavioral changes hypothesized to be adaptive to a seasonally-changing environment.
Randy Nelson (Advisor)
243 p.
photoperiod; seasonality; learning and memory; hippocampus; hypothalamic-pituitary-adrenal axis; hypothalamic-pituitary-gonadal axis; adult brain plasticity

Recommended Citations

Citations

  • Pyter, L. M. (2006). Seasonal plasticity of physiological systems, brain, and behavior [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1141319505

    APA Style (7th edition)

  • Pyter, Leah. Seasonal plasticity of physiological systems, brain, and behavior. 2006. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1141319505.

    MLA Style (8th edition)

  • Pyter, Leah. "Seasonal plasticity of physiological systems, brain, and behavior." Doctoral dissertation, Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1141319505

    Chicago Manual of Style (17th edition)

osu1141319505
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© 2006, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.