Early unilateral olfactory bulb lesion results in diffuse changes in behavior and overall cortical organization

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Goldsbury, Robin Paulette
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2007
The current work explores the behavioural and anatomical consequences of unilateral neonatal bulbectomy (OBX) in male and female rats at postnatal day 1 (PI) and P10. In adulthood the animals underwent a battery of motor and cognitive tests, and diffuse effects of early brain injury on the development of behavior were found. Disturbing olfactory sense input during development affected motor output. Rats normally display an equal distribution of right or left paw preference. In this study, both OBX sexes showed a shifted paw preference to the ipsilesional side, and forelimb deficits were found in a skilled reaching task. Lesion animals also showed enhanced performance on a visually driven spatial cognitive test. Cross-modal compensatory changes may be responsible. Morphological changes within the cerebral cortex are described, including bulbar changes, enlarged but fewer glomeruli, smaller accessory olfactory bulb, decreased downstream connectivity, and a rostral shift of the forebrain toward the olfactory bulb. Changes to the lateral cortex were found in both intact and lesion hemispheres, along with dendritic changes in the forelimb reaching area. Cellular regeneration within the lesion bulb was indicated. Changed shape and relative size increases compared to the intact bulb were found. BrdU labeling showed increased mitotic activity in P10 lesion animals. These findings demonstrate that the impact of olfactory injury during early development goes well beyond odor perception and discrimination, and that olfactory inputs during development significantly contribute to the development of the neocortex.
xix, 195 leaves : ill. (some col.) ; 29 cm.
Dissertations, Academic , Brain -- Research , Brain -- Wounds and injuries , Rhinencephalon , Rats as laboratory animals