No description available.

No description available.

No description available.

Adrenalectomy (ADX) has been shown to cause selective degeneration of granule cells in the dentate gyrus (DG). This occurs due to the reduction of corticosterone (CORT) and behavioural deficits are associated with the loss of these neurons. Dentate lesions and cell loss associated with ADX have been shown to effect behaviour in a number of spatial tasks. In contras, it has been shown granule cell loss does not affect the specificity of place cells in CA3 and CA1. We used the ADX model to examine the role of DG granule cells plays in representing space using immediate early gene (IEG) activation in the principal hippocampal subfields after exploration of novel environments. Rats were allowed to free explore multiple novel environments and then the mRNA for the IEG Homer 1a (H1a) was used as a marker of neural activity. After degeneration of approximately half of the DG granule cells we found a significant increase in number of active cells in the DG, CA3 and CA1 in ADX animals. The results indicate a reduction in granule cells causes a dramatic increase in the proportion of remaining DG granule cells in response to exploration. The change in DG activation disrupts the representations in CA3 and CA1 and thereby affects behaviour. / vii, 60 leaves : ill. (some col.) ; 29 cm

This thesis argues that as historians of English-Canadian poetry, A. J. M. Smith, John Sutherland, Northrop Frye, and Desmond Pacey explicitly promote the value of past conflict reconciled into present harmony. They do so by claiming that such reconciliation marks the maturity of English-Canadian culture. This thesis also argues, however, that the interactive progression of their histories implicitly undermines this value. It does so because each critic appreciates a different group of poets for realizing their shared cultural ideal, thereby establishing contradictory representations of what they all claim to be the culmination of English-Canadian literary history. The thesis concludes that while their lingering sense of present cultural maturity should now be fully renounced, the value these critics place on reconciliation is well worth preserving and transforming.

Thesis--Erlangen. / In Periodical Room. No doctoral dissertation statement. Stamped on cover: 1983 No 254.

Thèse doctorat : Sciences de l'éducation : Lyon 2 : 1981. / Titre provenant de l'écran-titre. Bibliogr.. Index.

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The mechanisms by which groups of neurons interact is an important facet to understanding how the brain functions. Here we study stochastic neural networks with delayed feedback. The first part of our study looks at how feedback and noise affect the mean firing rate of the network. Secondly we look at how the spatial profile of the feedback affects the behavior of the network. Our numerical and theoretical results show that negative (inhibitory) feedback linearizes the frequency vs input current (f-I) curve via the divisive gain effect it has on the network. The interaction of the inhibitory feedback and the input bias is what produces the divisive decrease in the slope (known as the gain) of the f-I curve. Our work predicts that an increase in noise is required along with increase in inhibitory feedback to attain a divisive and subtractive shift of the gain as seen in experiments [1]. Our results also show that, although the spatial profile of the feedback does not effect the mean activity of the network, it does influence the overall dynamics of the network. Local feedback generates a network oscillation, which is more robust against disruption by noise or uncorrelated input or network heterogeneity, than that for the global feedback (all-to-all coupling) case. For example uncorrelated input completely disrupts the network oscillation generated by global feedback, but only diminishes the network oscillation due to local feedback. This is characterized by 1st and 2nd order spike train statistics. Further, our theory agrees well with numerical simulations of network dynamics.

In this study, I examine the material culture of the Rio Fuerte Basket-Maker Phase (200 B.C. - 1000 A.D.) and Cave-Dweller Phase (1000 - 1600 A.D.) occupations in southern Chihuahua, Mexico, that is represented in the Dr. Robert Zingg Archaeological Collection. Zingg believed that the material culture showed a clear progression from the Basket-Maker Phase to the Cave-Dweller Phase, which he interpreted to indicate a relationship between these two phases, and that these phases were the precursors of the twentieth century Tarahumara. I test this hypothesis by comparing the artifacts in the Dr. Robert Zingg Archaeological Collection curated by the University Museum at Southern Illinois University Carbondale to the artifacts in the ethnographic Tarahumara Collection curated by the Milwaukee Public Museum. Following an evaluation of the archaeological and ethnographic material culture, I conclude that Zingg's hypothesis is only partially supported by the museum collections. Although the material culture of the later Cave-Dweller Phase is sufficiently similar to the material culture of the twentieth century Tarahumara to suggest a relationship between the two cultures, the earlier Rio Fuerte Basket-Maker Phase does not provide enough artifacts that show similarity with either the Cave-Dweller Phase or the twentieth century Tarahumara.