The acoustical properties of the external ears of rabbits, rats and guinea pigs have been investigated by means of microphone or probe implants in the ear canal or tympanic bulla and by cochlear microphone (CM) recordings. The directional properties and transfer functions of the external ears were monitored using pure tones and broadband sound under anechoic conditions.

The current classification of the Cynipoldea was subjected to compatibility analysis on the basis of the characters then employed and shown to have a very poor resolution. A comprehensive morphological investigation of 31 exemplar species was undertaken and 234 characters were found, a 450% increase over the established classification. These characters were analysed and the compatibility clique contained 135 apomorphies, 68 of which were synapomorphies. This is an increase of 600% and 300% respectively over the established data, this is a tremendous improvement in the data-base leading to a great improvement in resolution. In addition, the principal morphological character-suites were analysed independently. This technique was used to locate the weaknesses in earlier classifications and, by this method, the distortion caused by the allometric bias to wing-data was recognized. Many extralimital cynipoids were examined and a new tribe was discovered. Other forms of cladistlc analysis. Parsimony and O'Nolan weighting, were undertaken and the results considered. After detailed analysis, a phylogeny of the Cynipoidea was reconstructed. The evolutionary biology of the Cynipoidea provided particularly strong support for the phylogenetic reconstruction. Concepts of host defence, host range, gall complexity, gall position, host switching, reproductive cycles, biogeographical distribution, plate tectonics, palaeobotany, palaeoclimatology, the origin of hyperparasitism and the adaptive characters associated with xylophagous hosts were all considered. All the available fossil cynipoids were examined and the evolutionary history, holophyly, and relationships of the Cynipoidea with other Hymenoptera were all discussed. Finally the phylogenetic reconstruction was used to provide the first reasoned classification for the super family.

Single unit recordings of primary and central auditory fibers of the cricket Teleogryllus oceanicus show responses to frequencies over the range 1kHz to at least 42kHz. The characteristic frequencies, (ChFs) of units were distributed over most of the bandwidth investigated although few units were recorded with ChFs below 4kHz or in the region 7kHz to 10kHz. Some units showed more than one peak of sensitivity and others were broad-banded with no tuning to a particular frequency. Primary units whose ChFs approximated. to the carrier frequency (C.F.) of the species proclamation song were the most highly tuned. The derived threshold curves for all primary and central threshold data had major peaks of sensitivity at 4.8kHZ and 22kHz. The majority of primary units were not spontaneously active and had tonic response patterns but phasic responses were occasionally observed. Some central units have highly complex response patterns involving correlated spiking responses, silent periods and rebound activity. The response pattern of a single unit may vary with both the intensity and frequency of the stimulus. The implications of these findings are discussed.

No description available.

No description available.

Benzodiazepine (BZ) drugs, such as diazepam (Valium®) and chlordiazepoxide (Librium®), are widely prescribed for their sedative/anxiolytic properties but also impair mnemonic processes in both humans and animals. In the Morris water maze, an aversively motivated spatial learning task, BZs impair spatial learning but spare retention/performance. This spatial learning deficit cannot be attributed to sedation, gross sensorimotor impairments, hypothermia, state-dependent learning, or reductions of escape motivation (anxiolysis). The following series of experiments sought to further characterize the neurochemical, neuroanatomical, and electrophysiological substrates of BZ-induced impairments of spatial learning. In Experiment I, the role of endogenous BZs in spatial learning was assessed. The BZ receptor antagonists flumazenil (Ro 15-1788) and CGS 8216, as well as the BZ receptor inverse-agonist β-carboline, enhanced spatial learning in an inverted-U dose-dependent manner, suggesting that endogenously released BZs impede optimal learning. In Experiment II, the role of the BZ ω1 receptor subtype in spatial learning was assessed. CL 218,872, a selective agonist for the BZ ω1 receptor subtype, impaired spatial learning in a dose-dependent and flumazenil-reversible manner, thereby implicating the ω1 receptor subtype in BZ-induced amnesia. Together these results suggest that endogenous BZs activity, like BZ drugs, is detrimental to spatial learning and that specific BZ receptors mediate this impairment. Several neurochemical systems are important for spatial learning in the MWM and arc influenced by BZs. The contributions of two of these neurochemical systems, the opioids and acetylcholine (ACh), to the spatial learning deficit produced by BZs were assessed. In Experiment III, a better understanding of the role of opioid systems in spatial learning was sought. Morphine, a prototypical opioid, impaired spatial learning in a dose-dependent and naloxone-reversible manner. However, morphine also impaired performance and escape to a visible platform and its effects on spatial learning could be attenuated by increasing the escape incentive (colder water). This impairment pattern suggests that morphine impairs spatial learning by reducing escape motivation. Because both BZs and cold water immersion increase endogenous opioid activity, it seemed possible that the combination of drug- and water-induced opioid release might mediate the spatial learning deficit produced by BZs. In Experiment IV, naloxone, an opioid receptor antagonist, completely blocked the spatial learning deficit produced by morphine but failed, even at a higher dose, to block the spatial learning deficit produced by diazepam . Conversely, flumazenil, a BZ receptor antagonist, completely blocked the spatial learning deficit produced by diazepam but failed to affect the amnesic effects of morphine. Together, these findings strongly suggest that the spatial learning deficit produced by BZs is not due to enhanced opioid activity. There is also biochemical evidence that BZs interact with ACh systems. In Experiment V, flumazenil attenuated the spatial learning deficit produced by scopolamine, an ACh (muscarinic) antagonist, but physostigmine, an acetylcholinesterase inhibitor, failed to attenuate the spatial learning deficit produced by chlordiazepoxide, even at doses that completely reversed the spatial learning deficit produced by scopolamine. Together these results fail to support the notion that BZs impair spatial learning by reducing ACh activity but suggest that scopolamine impairs spatial learning by enhancing endogenous BZ activity. Several neuroanatomical regions possess a high density of BZ receptors and are also integral for spatial learning in the MWM. In Experiment VI, infusions of chlordiazepoxide into the medial septum, but not frontal cortex, nucleus basalis magnocellularis, amygdala, hippocampus, or cerebellum, impaired spatial learning but had little effect on anxiety. Conversely, infusions of chlordiazepoxide into the amygdala reduced anxiety but had little effect on spatial learning. These results suggest that the medial septum mediates the amnesic effects of BZs and that the amygdala mediates the anxiolytic effects. In Experiment VII, intraseptal infusions of chlordiazepoxide were additionally found to impair spatial learning in a dose-dependent and flumazenil-reversible manner. However, infusions of flumazenil into the medial septum failed to block the amnesic effects of systemically administered chlordiazepoxide, suggesting that the amnesic to effects of BZs are not mediated by the medial septum exclusively. Tetrahydroaminoacridine, an acetylcholinesterase inhibitor, failed to attenuate the spatial learning deficit produced by intraseptal infusions of chlordiazepoxide, suggesting that the deficit was not due to a disruption of the septohippocampal ACh projection. Together, these results suggest that chlordiazepoxide impairs spatial learning by interacting with the septohippocampal GABAergic projection. The septohippocampal GABAergic projection regulates the excitability of hippocampal afferents (e.g., perforant path). Experiment VIII assessed the effects of systemically administered BZs on the induction of long-term potentiation (LTP) in the perforant path. CL 218,872, but not chlordiazepoxide or diazepam , significantly suppressed long-term potentiation. However, all drugs impaired spatial learning. These findings suggest that CL 218,872 impairs spatial learning by suppressing LTP but that BZ-induced spatial learning deficits can occur in the absence of perforant path LTP suppression. Taken together, the above results suggest that endogenous BZ systems, particularly those in the septohippocampal system, are important modulators of mnemonic processes. These findings are discussed in the context of understanding information storage processes and the implications for clinical populations. / Graduate

Thesis (M. S.) - Florida State University. / Bibliography: leaves 136-142.

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There is a need for a refined understanding of large carnivore prey preference and carrying capacity (K). To date, K estimates for large carnivores have been developed from predictions of carnivore diet at a prey and predator species-level. These predictions therefore assume that all social classes within a carnivore species display similar prey preferences and that all demographic classes within a prey species are equally preferred or avoided. The objective of this study was to investigate the importance of including prey demographics and carnivore social class in carnivore diet descriptions and thereby K estimates, using cheetah Acinonyx jubatus as a study species. It was predicted that prey sex, prey age and cheetah social class influence cheetah prey preferences, when they influence the risk and ease of prey capture, and that their inclusion in a K model would improve its predictive strength. Based on an analysis of 1290 kills from South Africa, male coalition cheetah were found to prefer a broader weight range of prey than solitary cheetah. Prey demographics further influenced cheetah prey preference, when it corresponded to differences in prey size and the presence of horns. The current species-level K regression model for cheetah is based on preferred prey and thus omits highly abundant antelope that often comprise the majority of the diet, an artefact of the way in which preferences are calculated. A refinement of the species-level K regression model, to account for prey demographic- and cheetah social class-level differences in diet and the biomass of accessible prey (defined in this study as all non-avoided prey) instead of just preferred prey, doubled the predictive strength of the K model. Because group-hunting enabled predation on a broader weight range of prey, cheetah K was influenced by the ratio of male coalition cheetah to solitary cheetah in the population. The refined K regression model is derived from ecosystems supporting an intact carnivore guild. A mechanistic approach to estimating K, based on Caughley‟s (1977) maximum sustainable yield model, therefore better predicted cheetah K in systems devoid of lion Panthera leo and African wild dog Lycaon pictus, which were found to suppress cheetah density. This study improves our understanding of the relationships between prey demographics, cheetah social classes and intra-guild competition in determining cheetah prey preferences and K. This study therefore paves the way for similar work on other large carnivores.