Brain research
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Exposure to ethanol during pregnancy can be devastating to the developing nervous system, leading to significant central nervous system dysfunction. The hippocampus, one of the two brain regions where neurogenesis persists into adulthood, is particularly sensitive to the teratogenic effects of ethanol. In the present study, we tested a rat model of fetal alcohol syndrome (FAS) with ethanol administered via gavage throughout all three trimester equivalents. ⋯ However, we detected a significant increase in the number of new immature neurons in animals that were exposed to ethanol throughout all three trimester equivalents. This result might reflect a compensatory mechanism to counteract the deleterious effects of prenatal ethanol exposure or an ethanol-induced arrest of the neurogenic process at the early neuronal maturation stages. Taken together these results indicate that exposure to ethanol during the period of brain development causes a long-lasting dysregulation of the neurogenic process, a mechanism that might contribute, at least in part, to the hippocampal deficits that have been reported in rodent models of FAS.
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Jaw-clenching and tooth-grinding associated with bruxism can contribute to abnormal tooth wear and pain in the masticatory system. Clench and tooth-grinding jaw-movement tasks were evaluated in a block-design fMRI study comparing a dental-control (DC) group with a tooth-grinding (TG) group. Group classification was made prior to imaging based upon self-reported parafunctional clench and grind behavior and clinical evidence of abnormal tooth wear. ⋯ Neither task elicited more activity in the TG than DC subjects. Our group findings suggest that jaw-movement tasks executed by the TG group elicited (1) more efficient brain activation pattern consistent with other studies that found less extensive activity with executing "over-learned" tasks; (2) "underactive" SMA activity that underlies reduced motor planning; (3) decreased inferior parietal activity that is associated with lesser motor-attentional demands. Thus orofacial parafunctional habits may influence brain circuits recruited for jaw movements, providing a possible basis for understanding involuntary jaw movements in bruxism and oral movement disorders in general.