1. Lymnaea was the subject of an established behavioural conditioning paradigm where pairings of a neutral lip tactile stimulus (CS) and a sucrose food stimulus (US) results in a conditioned feeding response to the CS alone. The current objective was to dissect trained animals and examine electrophysiological changes in the feeding circuitry which may underlie this learning. 2. Naive subjects were used to confirm that US and CS responses in vivo persisted in vitro since this is a pre-requisite for survival of a learned memory trace. This required the development of a novel semi-intact preparation facilitating CS presentation and simultaneous access to the CNS. 3. The nature and function of the CS response was investigated using naive animals. Intracellular recordings revealed that the tactile CS evokes specific, consistent synaptic responses in identified feeding neurons. Extracellular recording techniques and anatomical investigations showed that these responses occurred through a direct pathway linking the lips to the feeding circuitry. A buccal neuron was characterized which showed lip tactile responses and supplied synaptic inputs to feeding neurons indicating that it was a second-order mechanosensory neuron involved in the CS pathway. 4. Animals trained using the behavioural conditioning paradigm were tested for conditioned responses and subsequently dissected~ Intracellular recording from specific identified feeding motoneurons revealed that CS presentation resulted in significant activation of the feeding network compared to control subjects. This activation was combined both with an increase in the amplitude of a specific synaptic input and an elevation in the extracellular spike activity recorded from a feeding-related connective. A neuronal mechanism to account for these findings is presented. 5. The role of motoneurons in the feeding circuit was reassessed. It is demonstrated, contrary to the current model, that muscular motoneurons have an important contribution during feeding rhythms through previously unreported electrotonic CPG connections.

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Thesis (Ph. D.)--Washington State University, May 2009. / Title from PDF title page (viewed on Feb. 12, 2010). "Department of Entomology." Includes bibliographical references.

No description available.

Dissertation (PhD)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1985. / Vita. Abstract. Includes bibliographical references (leaves 118-127). Also available via the Internet.

The present research aims to establish the depth of abiotic and invertebrate edge-effects occurring in plantations of two conifer species, and the resulting effects of management practices on 'edge' and 'core' invertebrate communities. Near complete invertebrate samples were collected using chemical knockdown allowing analysis of invertebrates at the order, family, genus, species and guild level. Similar invertebrate densities per m[2] ground area occurred in both tree species, although communities differed between them, Pinus sylvestris supporting a more diverse community than Picea sitchensis. Species richness, diversity and densities varied with distance from plantation edge with the Acarina, Araneae, Coleoptera, Collembola, Diptera and Hemiptera showing particularly strong responses to edge proximity. Abiotic edge-effects, although variable between transects, occurred to an average depth of 30 metres with an approximate 1 C drop in temperature and a 5% increase in relative humidity towards the core. Invertebrate edge-effect depths varied with species, ranging from 5 to 80 metres. In P. sitchensis invertebrate richness and densities, particularly for Coleoptera, Araneae and Hemiptera were higher in the edge habitat, whilst increased richness and diversity occurred in the core of P. sylvestris. Edge habitat is key to optimising richness in P. sitchensis, however application of core-area models shows that current plantation management fails to maximise edge habitat. Reduction of patch size and/or increasing edge features will increase species richness. In contrast core habitat is vital to species richness in P. sylvestris. Current small patch size limits invertebrate richness, increased patch size and implementation of edge buffer zones would protect core habitat thus enhancing invertebrate species richness.

Stream quality along the Natchez Trace Parkway was evaluated by hydrologic unit code 4 (HUC4) watersheds and habitat assessment scores as a broad and local scale, respectively. Water chemistry parameters and rapid bioassessment techniques for habitat and fish and invertebrate communities were sampled in 18 streams and six HUC4 watersheds. Forest, agriculture, and developed land use had little variation at HUC4 level; land use impacts could not be determined. Turbidity and TSS were important factors determining habitat scores and created a “boundary” separating southern and northern watersheds. A latitudinal trophic shift was observed of fish omnivoreinsectivore- piscivore in southern watersheds to generalist-insectivore-herbivore species in northern watersheds. Fish families were correlated significantly to the water chemistry matrix. Fish species were correlated significantly with the habitat matrix using Canonical Correspondence Analysis. Management implications differ considering the function of these two scales. Only turbidity and percentage cobble substrate were significant at both scales.