Assessing motor and cognitive function to detect shifts in brain function in two models of Parkinson\u27s disease

Cognitive changes accompany and often precede the onset of classic motor deficits typical of Parkinson&;#8217;s disease. A current focus of Parkinson&;#8217;s research has become understanding the development and progression of pre-motor cognitive changes. Based on previous research showing that hippocampus-sensitive spatial learning can be enhanced at the cost of impaired striatum-sensitive response learning, we hypothesized that changes in the balance between these two cognitive systems could be used as a proxy for the relative strength or health of their associated brain regions. Because non-motor symptoms of Parkinson&;#8217;s disease can precede the onset of the diagnostic motor dysfunction, changes in the balance between distinct learning strategies may represent an early marker of Parkinson’s-related neurodegeneration. Two rat models were used to assess the relationship between Parkinson’s disease-related motor dysfunction and changes in cognition. In the first study, a 6-OHDA rat model of Parkinson’s disease was used to generate a partial lesion of dopaminergic neurons in the nigrostriatal pathway. Despite the probable depletion of dopamine in the nigrostriatal pathway of lesioned rats that presented as impairment in two motor tasks, rats showed enhanced performance on the cognitive spontaneous alternation task, a test of spatial working memory. However, recent data suggest that multiple brain regions, including both the hippocampus and striatum, are activated during performance of the spontaneous alternation task; Parkinson’s-induced enhancements on this task may not be due solely to a shift in cognitive balance. Previous data show that inactivation of the hippocampus can enhance striatum-sensitive learning; however, it is unclear if inactivation of the striatum enhances hippocampus-sensitive functions. Prior to determining the effect of a 6-OHDA-induced lesion on hippocampus-sensitive learning, we wanted first to assess how impairing striatum function modulated place learning to determine cognitive shifts in rats with an intact brain. The second study uses two single-solution cognitive tasks that may link more closely to activation of separate neural systems. Temporary inhibition of the dorsal striatum by the GABAA receptor agonist, muscimol, produced deficits in motor function similar to those seen in the 6-OHDA model of Parkinson’s. Intrastriatal muscimol also impaired learning on a striatum-sensitive response learning task, suggesting that striatum-sensitive motor processes may overlap with striatum-sensitive cognitive processes. However, muscimol-induced striatum dysregulation did not produce enhancements on a hippocampus-sensitive spatial learning task. It is possible that the cognitive enhancements in hippocampus-sensitive processes are maximized when only specific neurotransmitter systems are dampened, such as the loss of dopaminergic signaling seen in Parkinson’s disease. Unlike 6-OHDA, which targets dopaminergic neurons, muscimol activates GABAA receptors, leading to the opening of Cl- channels, altering membrane potentials, and changing the likelihood of neurotransmitter release. Thus, activation of GABAA receptors by muscimol will alter neuron activity regardless of neurotransmitter system while 6-OHDA must initially affect dopaminergic neurons. Consequently, it is possible that muscimol decreases activity in neurotransmitter systems that play a compensatory role following 6-OHDA-induced dopaminergic degeneration. As such, a generalized inhibitor of neural activity like muscimol, may disrupt neural processes that are integral for seeing the Parkinson’s disease-related cognitive enhancements

Climate, conflict and internal migration in Colombia

Robust empirical evidence on the potential causal linkages between environmental change, conflict and migration is scarce. We evaluate this relationship in the context of internal migration in Colombia for the period from 2000 to 2005. Using municipalitylevel data in a gravity model that considers the issue of endogenous selection regarding both the outbreak of conflicts and the existence of non-zero migration flows, we establish an empirical causal link between droughts, conflict and migration. Our results show a positive relationship between the severity of droughts and the likelihood of conflicts, as well as between conflicts and human mobility, suggesting an indirect effect of climate on internal migration in Colombia

Nuclear Progesterone Receptors Are Up-Regulated by Estrogens in Neurons and Radial Glial Progenitors in the Brain of Zebrafish

In rodents, there is increasing evidence that nuclear progesterone receptors are transiently expressed in many regions of the developing brain, notably outside the hypothalamus. This suggests that progesterone and/or its metabolites could be involved in functions not related to reproduction, particularly in neurodevelopment. In this context, the adult fish brain is of particular interest, as it exhibits constant growth and high neurogenic activity that is supported by radial glia progenitors. However, although synthesis of neuroprogestagens has been documented recently in the brain of zebrafish, information on the presence of progesterone receptors is very limited. In zebrafish, a single nuclear progesterone receptor (pgr) has been cloned and characterized. Here, we demonstrate that this pgr is widely distributed in all regions of the zebrafish brain. Interestingly, we show that Pgr is strongly expressed in radial glial cells and more weakly in neurons. Finally, we present evidence, based on quantitative PCR and immunohistochemistry, that nuclear progesterone receptor mRNA and proteins are upregulated by estrogens in the brain of adult zebrafish. These data document for the first time the finding that radial glial cells are preferential targets for peripheral progestagens and/or neuroprogestagens. Given the crucial roles of radial glial cells in adult neurogenesis, the potential effects of progestagens on their activity and the fate of daughter cells require thorough investigation

(Putative) sex differences in neuroimmune modulation of memory

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134408/1/jnr23921.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134408/2/jnr23921_am.pd

ORCHARD BIRD CONTROL

Seven primary factors. The difficulties associated with the control of birds in an orchard are usually related or confounded by four primary, unknown factors and three which are usually quite well known. The four unknowns are: 1. The species causing the damage. 2. The total bird population in the area. 3. The alternate food sources available for the birds. 4. The relative economic importance of the crop to the community in which it is produced. The three known factors which are usually evident: 1. The crop being damaged. 2. The economic importance of the crop to the grower. 3. The prevailing attitudes of the agricultural and non-agricultural resi dents of the community. These are like the primary flight feathers of a bird—the number of these primaries may vary, not necessarily with species, season, sex or age-but rather basically, with geographic distribution. They are, in any given geographic locality, the Seven Horns of a Dilemma, which confront the fruit grower with a bird problem. The seven divided. Perhaps the term multiplied would be more appro-priate, but it does not serve to make poignant the fractures which may occur in each factor to confound a practical solution to the problem of orchard bird control. The development of a practical control is dependent upon the proper evaluation of all factors. A failure in the proper functioning of the primary feathers may be disastrous to the bird; and failure to properly evaluate the factors associated with bird control might well result in disastrous consequences for the grower, the community at large, and an endangered species. However, as we recognize that man may cause an evolutionary development to the detriment of a species, let us not forget that he is an integral part of that change and that he can and probably does cause the development of an endangering species

United States Exploration in the Antarctic, 1789 to 1842

322 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1952.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD