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No abstract available. / Thesis (M.Sc.)-University of Durban-Westville, 1990.

The purpose of the current thesis was twofold: (1) to examine various factors that might be contributing to age-related learning and memory deficits specifically related to the hippocampus, and (2) to validate our rat model of aging, employing a multilevel analysis. We found age-related deficits on both spatial and non-spatial hippocampus-dependent taks that were accompanied by structural alterations observed in vivo (volune, but not neuronal metabolic function) and post mortem (neuronal density and neurogenesis, but not synaptic or mitochondrial density). Furthermore, our results suggest that the observed hippocampal structural changes, named decreased volume and neurogenesis, predict learning and memory deficits, and both can be accounted for by neurogenic reduction. In addition, the above-mentioned pattern of age-related deficits closely resembles that seen in humans, suggesting the present rat version of aging to be a very useful model for investigating hippocampal aging in humans. / iii, 236 leaves : ill. (some col.) ; 29 cm.

This thesis investigates the behavioural and anatomical correlates of recovery from motor cortex damage in rats. The effectiveness of behavioural, pharmacological, and regenerative treatments was investigated using models of focal stroke. Chronic bilateral motor deficits were found after motor cortex damage induced by various methods. These behavioural deficits were similar in severity and duration although they were correlated with different patterns of reorganization seen in Golgi-stained tissue. Animals with motor cortex injury benefited from postinjury olfactory stimulation, chronic administration of nicotine, and infusions of epidermal growth factor followed by erythroprotein. Different mechanisms of plasticity in remaining cortical circuits are discussed as possible candidates responsible for the behavioural improvement. The current thesis expands the current knowledge of the effects of adult cortical damage to ares critical to motor control. It may also stimulate research on therapies and possible mechanisms that might enhance recovery after stroke. / xviii, 299 leaves : ill. (some col.) ; 29 cm.

Basic fibroblast growth factor (FGF-2) is a trophic molecule involved in a number of functions within the central nervous system (CNS), including a prominent role in the regulation of CNS responses to injury. Prior studies suggest that rats recover differently from injury inflicted to different regions and at different ages throughout development, and that FGF-2 might underlie this phenomenon. This thesis examined whether the functional and structural outcome following bilateral injury to the motor cortex inflicted at postnatal day (P10) could be ameliorated by exogenous administration of a growth factor (FGF-2). Four complimentary studies were conducted that each assessed the role of FGF-2 in mediating recovery from bilateral motor cortex injury inflicted at P10. We found that FGF-2 improves physiological, anatomical, and functional outcome from bilateral lesions to motor cortex at P10. / xiii, 171 p. : ill. ; 28 cm.

Basic fibroblast growth factor (bFGF) has been implicated in the brain's trophic response to injury. This thesis examined the effects of endogenous bFGF on brain plasticity and recovery of behavioral function following cortical injury in adult rats. The first experiment investigated the post-lesion time course of the astrocytic expression of bFGF. Subsequent experiments examined the effects of injury-induced bFGF on neuroonal morphology, cortical morphology, and post-lesion behavioral deficits. Following motor cortex injury, endogenous bFGF prevented neuritic degeneration in layer V pyramidal neurons in Zilles' area Fr2 and promoted recovery of function in the Whishaw Reaching Task. Housing rats in an enriched environment prior to cortical injury enhanced the expression of bFGF but did not increase cortical thickness nor reduce post-lesion behavioral deficits (relative to laboratroy-housed rats). Collectively, these experiments indicate that injury-induced bFGF plays a role in potentiating recovery from brain damage. This implies that bFGF may be beneficial as a treatment following brain injury. / x, 123 p. ; 28 cm.

The current studies investigate the behavioral and anatomical changes after lesions at different ages of the cingulate cortex. Rats received lesions of the posterior cingulate cortex (PCing) or the anterior and posterior cingulate cortex (Total) at: postnatal day 4 (P4); day 10 (P10), or in adulthood (P120). Rats were trained in the Morris water maze, the Whishaw reaching task, conditioned taste aversion (CTA), and their activity was monitored over 48 hours. The general finding was a significant behavioral recovery on P10 animals regardless the size of the lesion. This recovery was associated with an increase in dendritic arborization in P10 animals with the PCing removed and a partial regeneration of the midline tissue in the Total P10 animals. These results suggest that damage to the cingulate cortex at P10 is associated with substantial behavioral and anatomical plasticity and that removal of the frontal midline tissue stimulates a regenerative process in more posterior cortex that does not occur otherwise. / ix, 111 leaves : ill. ; 29 cm.

This thesis focuses on the effects of pharmacological and environmental interventions following perinatal prefrontal cortex lesions. Rats given postnatal day 3 medial prefrontal cortex lesions were provided with one of the following treatments: basic fibroblast growth factor (bFGF), complex-housing, tactile stimulation, or a combined treatment of both bFGF and tactile stimulation or bFGF and complex-housing. Rats given postnatal day 3 orbital prefrontal cortex lesions were housed in a complex environment. The findings of these studies suggest that bFGF, complex-housing or tactile stimulation are beneficial after early brain injury. The combined treatment of bFGF with complex-housing provides a synergistic effect, as the combined condition is more advantageous than bFGF alone. In contrast, the combined treatment of bFGF with tactile stimulation produced adverse effects. These results suggest that pharmacological and environmental manipulations change cortical plasticity and therefore functional recovery after neonatal cortical injury. / xv, 177 leaves : ill. (some col.) ; 29 cm.

This thesis examined the role of exogenous basic fibroblast growth factor (FGF-2) in stimulating recovery after early cortical injury. Rats with medial prefrontal cortex (MFC), posterior parietal cortex (PPC), or sham lesions at postnatal day 3 (P3) received one of three variations of FGF-2 treatment: postnatal FGF-2 that was either pre-mixed or prepared daily, or prenatal FGF-2, and tested in adulthood. Behavioral tests used were: 1) the Morris Water task and, 2) the Whishaw Tray Reaching task. The level of functional recovery attained was dependent on FGF-2 preparation and the developmental period. MFC lesion rats showed good recovery but there was a differntial effect of pre and postnatal FGF-2 that appeared to be related to task. PPC rats showed greater recovery after postnatal rather than prenatal treatment. Anatomical changes were restricted to groups with relatively good functional recovery. These findings suggest a multifunctional role of FGF-2 in the injured brain. / xvi, 223 leaves : ill. ; 29 cm.

Neural changes in the forelimb cortex were studied at Postnatal (P) 10, 15, 20, 25, 30, and 100 days. Six biological markers of brain development, cortical thickness, Layer III pyramidal cell morphology, glial fibrillary acidic protein (GFAP), myelination, c-fos activity and Acetylcholinesterase (AChE) were correlated with the behavioural development of reaching, bimanual coordination, postural adjustment, and defensive feeding behaviours. The behaviours were filmed from P15 until P30 and then also in adulthood. For the behaviours there was a gradual development of the skilled patterns of paw and digit use seen in adults as well as in the patterns of movements in postural adjustment, carry behaviours and dodging and robbing type behaviours. The development of the adult patterns of movement were correlated to the morphological and biochemical changes in the cortex. The results suggest that the maturation of skilled movements depends upon anatomical and neurochemical maturation of the neocortex as well as upon learning. / x, 132 leaves : ill. ; 28 cm.