Thesis (M.Sc.)(Psych.)--University of Melbourne, Dept. of Behavioural Sciences, 2006. / Typescript. Includes bibliographical references (leaves 132-148).

Thesis (Ph.D.)--Drexel University, 2010. / Includes abstract and vita. Includes bibliographical references (leaves 99-114).

Thesis (Ph.D.)--Drexel University, 2010. / Includes abstract and vita. Includes bibliographical references (leaves 95-104).

M.A. / Himmehoch (1984, 1987) in discussion of major mood disorders related to epilepsy, describes an affective condition termed subictal mood disorder. Patients with subictal mood disorder are divided into manic-depressive and dysthymic subtypes, the former resembling an atypical, usually rapid-cycling bipolar mood disorder. The latter dysthymic group, are characterised by a baseline dysthymia, severe recurrent depressive episodes, and transient euphorias. In addition, these dysthymic patients are described as being especially prone to impulsive suicide attempts, extreme irritability, rage outbursts and deliberate self-harm. Himmelhoch (1984, 1987) postulates temporolimbic dysfunction with both ictal and subictal (subclinical) changes as the underlying aetiology. Temporolimbic phenomena such as anamnesic, dissociative and perceptive distortions are important aspects of neuropsychiatric phenomenology. Clinical evidence, however, suggests that these occurrences are not routinely sought for or uncovered during the clinical evaluation of patients and their relevance for atypical affective presentations not clearly understood. The aim of this clinical survey was to evaluate the presence and nature of both temporolimbic dysfunction and subictal mood disorder among a subpopulation of private psychiatric patients. Furthermore in order to explicate a possible association between the above, the electroencephalographic records of these patients were examined. Records of 761 patients who attended a private practice over a two-year period were retrospectively reviewed. 546 patients had been questioned in sufficient detail and were deemed reliable in their responses. Of the 546 patients reviewed 128 (23,4%) were found to have experienced significant temporolimbic phenomena. The most common features were dissociative states, deja vu, premonitions, jamais vu and tactile hallucinations. 150 (27,5%) patients met Himmelhoch's criteria for the presence of subictal mood disorder. Of those 150, 100 (66,7%) demonstrated significant temporolimbic phenomena. EEG results, with the exclusion of 16 patients (the appropriate records not being available), highlighted 64 iY (76,2%) ofthe probands as having met the criteria for significant temporolimbic phenomena and subictal mood disorder and demonstrating unequivocal abnormality onEEG. Taking into account the sample bias of this particular private practice, and the obvious flaws of a retrospective, naturalistic survey of this nature, the concept of sub ictal mood disorder is discussed. Case vignettes are used to illustrate the phenomenological presentation ofthese patients and the potential benefits of the addition of anticonvulsants in their management.

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It is well established that patients with temporal lobe epilepsy (TLE) commonly report memory difficulties. The aim of this thesis was to use a novel approach adopting Nelson & Narens' (1990) theoretical framework to investigate whether metacognitive knowledge and memory performance were differentially disrupted in patients with TLE. More specifically, investigating to what extent poor memory in TLE could result from inadequate metamemory monitoring, inadequate metamemory control or both. Experiment I employed a combined Judgement-of-Learning and Feeling-of-Knowing task to investigate whether participants could monitor their memory successfully at both the item-by-item and global levels. The results revealed a dissociation between memory and metamemory in TLE patients. TLE patients presented with a clear episodic memory deficit compared with controls yet preserved metamemory abilities. Experiments 2 and 3 explored the sensitivity approach to examine metacognitive processes that operate during encoding in TLE patients and controls. Both these experiments demonstrated that TLE patients were sensitive to monitoring and control processes at encoding. The final experiment further investigated memory performance by examining the role of lateralisation of the seizure focus using material specific information and the 'Remember-Know' paradigm. The findings from the verbal task provided partial support to the material-specific hypothesis. The results from these experiments are discussed in terms of their association with executive functioning and memory deficits in TLE, and have important implications for future research examining memory and metamemory in TLE patients and other clinical populations.

<p>Temporal lobe epilepsy is a common and devastating disorder that features recurrent seizures and is often associated with pathologic anxiety and hippocampal sclerosis. An episode of prolonged seizures (status epilepticus) is thought to promote development of human temporal lobe epilepsy years later. A chemical-genetic approach established proof of concept that transiently inhibiting the receptor tyrosine kinase, TrkB, following status epilepticus prevented epilepsy, anxiety-like behavior and hippocampal damage in a mouse model, providing rationale for developing a therapeutic targeting TrkB signaling. To circumvent the undesirable consequence that global inhibition of TrkB exacerbates neuronal degeneration following status epilepticus, we sought to identify both the TrkB-activated signaling pathway mediating these pathologies and a compound that uncouples TrkB from the responsible signaling effector. To accomplish these goals, we used genetically modified mice and a model of seizures and epilepsy induced by a chemoconvulsant. Genetic inhibition of TrkB-mediated phospholipase C gamma 1 (PLC gamma 1) signaling suppressed seizures induced by a chemoconvulsant, leading to design of a peptide (pY816) that inhibited the interaction of TrkB with PLC gamma 1. We demonstrate that pY816 selectively inhibits TrkB-mediated activation of PLC gamma 1 both in vitro and in vivo. Treatment with pY816 prior to administration of a chemoconvulsant suppressed seizures in a dose- and time-dependent manner. Treatment with pY816 initiated after chemoconvulsant-evoked status epilepticus and continued for just three days suppressed seizure-induction of epilepsy, anxiety-like behavior and hippocampal damage assessed months later. This study elucidates the signaling pathway by which TrkB activation produces diverse neuronal activity-driven pathologies and demonstrates therapeutic benefits of an inhibitor of this pathway in an animal model in vivo. A strategy of uncoupling a receptor tyrosine kinase from a signaling effector may prove useful in diverse diseases in which excessive receptor tyrosine kinase signaling contributes.</p> / Dissertation

Defining language lateralisation is important to minimise morbidity in patients treated surgically for temporal lobe epilepsy (TLE). Functional magnetic resonance imaging (fMRI) offers a promising, non-invasive, alternative strategy to the Wada test. Here, fMRI has been used to study healthy controls and patients with TLE in order (i) to define language-related activation patterns and their reproducibility; (ii) to compare lateralisation determined by fMRI with that from the Wada test; and (iii) to explore the usefulness of multiple fMRI language paradigms. 18 healthy controls (12 right-handed and 6 left-handed) and 24 pre-operative TLE patients (19 right-handed: 12 left-TLE, 7 right-TLE; 5 left-handed: 2 right-TLE, 3 left-TLE) were studied using fMRI. Four fMRI language paradigms used: phonetic and semantic fluency, and the naming of living and non-living things. The data for all 4 tasks were acquired during a single scanning session on two occasions. All patients also underwent Wada testing. In patients and controls, phonetic and semantic fluency tasks were robustly activating and strongly lateralising. Quantified language-related lateralisation from fMRI verbal fluency data was highly reproducible and concordant with the lateralisation of the Wada test. Both fluency tasks identified patients with atypical language lateralisation, including 4/12 right-handed patients with left-TLE and 4/5 left-handed TLE patients, regardless of the side of epileptic focus. In comparison, the two confrontational naming tasks were not strongly lateralising and did not reliably agree with Wada lateralisation in either 12 right-handed controls or 19 right-handed patients with TLE. However, there was a difference in the pattern of fMRI activation in right-handed pat ients with left-TLE. Left-TLE patients had a more right lateralised network of activation when naming living things relative to non-living things, suggesting that some patients may be at risk of a category specific naming decline for non-living things after left anterior temporal lobectomy. These results demonstrate that non-invasive fMRI measures of languagerelated lateralisation may provide a practical and reliable alternative to invasive testing for pre-surgical language lateralisation in patients with TLE. The high proportion of TLE patients showing atypical language lateralisation suggests considerable plasticity of language representation in the brains of patients with intractable TLE.

Cyclin-dependent kinase-5 (Cdk5) was identified as a serine/threonine kinase that plays an important role in neuronal development. Association with one of the neuronal activators, p35 or p39, is required for Cdk5 to elicit its diverse effects in the nervous system, such as neurite outgrowth. In addition to these, increasing evidence suggests that Cdk5 also plays an important role in cocaine addiction, neurotransmitter release, NMDA receptor phosphorylation. This thesis is divided into three parts which deals with the effects of Cdk5 inhibitor¡Ðroscovitine on the morphine tolerance development, acute inflammatory pain, and pilocarpine-induced seizure respectively. The first part explored the effect of Cdk5 inhibitior¡Ðroscovitine on the morphine antinociceptive tolerance development. Delta FosB activation is involved in morphine tolerance. Cyclin-dependent kinase- 5 (Cdk5) is found to be the downstream target of delta FosB. We examined the effects of the potent selective Cdk5 inhibitor¡Ðroscovitine on the development of antinociceptive tolerance of morphine. Tolerance was induced by continuous infusion of morphine 5 &#x00B5;g/hr intrathecally (i.t.) for 5 days. The effect of co-administration of roscovitine 1 &#x00B5;g/hr i.t. for 5 days was also examined. Roscovitine co-administration enhanced the antinociceptive effect of morphine in morphine tolerant rats. It also shift the morphine antinociceptive dose¡Ðresponse curve to the left during morphine tolerance induction, and reduced the increase in the ED50 of morphine two-fold. Collectively, these findings suggest Cdk5 modulation may be involved in the development of morphine tolerance and its inhibitor will enhance antinociceptive effect. The second part discussed the roscovitine effect on acute inflammatory pain. Formalin injected into the rat hind paw will evoke flinching (consisting of an elevation and shrinking back of the injected paw), a reliable parameter of pain behavior. The nociceptive response to formalin occurs in a biphasic pattern: there isan initial acute period (phase 1), and after a short period of remission, phase 2 begins and consists of a longer period (1 hour) of sustained activity. The initial response was initially attributed to a direct algogenic effect of formalin, whereas phase 2 was associated with the central sensitization. In this study, the Cdk5 inhibitor¡Ðroscovitine was injected intrathecally to elucidate the mechanism of Cdk5 activation during formalin-induced hyperalgesia. The 50 ul of 5% formalin solution was used as the noxious stimulant. The rats were injected with 0, 50, 100, and 200ug roscovitine intrathecally thirty minutes before hind paw formalin injection. Intrathecal 200ug roscovitine injection attenuates the phase I flinch response. And intrathecal 50, 100, and 200ug roscovitine injection suppress phase II flinch response effectively. Roscovitine administration could effectively suppress the formalin-induced flinch behavior. This implies the activation of Cdk5 plays an important role in the sensitization after nociceptive stimulation. The third part focus on the roscovitine effect on the pilocarpine induced seizure. Pilocarpine temporal lobe epilepsy model is widely used. Chronic electroconvulsive therapy could upregulate Cdk5 activity. Cdk5 inhibitor¡Ðroscovitine could suppress NMDA induced long-term potentiation in hippocampal slice. Intracerebroventricular injection of 100£gg roscovitine 30 min before pilocarpine-induced epilepsy could significantly decrease the seizure-induced mortality ( 11% in roscovitine group VS 77% in control group). The escape latency, spatial memory impairment, in the pilocarpine-induced seizure group is significant longer than the roscovitine pretreatment group in the Morris water maze test after one month (p¡Õ0.05). It is concluded Cdk5 may play an important in the pathogenesis of epilepsy. Therefore, Cdk5 inhibition may become another way for the epilepsy treatment.

The purpose of this study was to investigate the association between extracellular basal hippocampal glutamate levels and cognitive function in epileptic patients. We used the zero-flow microdialysis method to measure the extracellular concentrations of glutamate in the epileptogenic and non-epileptogenic hippocampus of 23 awake epileptic patients during the interictal period. All patients underwent extensive neuropsychological testing to assess cognitive functioning prior to probe implantation. Basal glutamate levels in the epileptogenic hippocampus were significantly higher than the non-epileptogenic hippocampus (mean, 11.96 micromolar (µM) versus 2.92 µM, respectively). Elevated basal glutamate levels in the epileptogenic hippocampus correlated with decreased scores on the Verbal Selective Reminding Test (V-SRT) (R[exponent]2 = 0.36, p = 0.0244). When controlling for MRI-detected hippocampal atrophy within epileptogenic regions, elevated basal glutamate levels within atrophic hippocampus correlated with decreased cognitive functioning measured by both the V-SRT (R[exponent]2 = 0.7764, p = 0.0204) and Performance Intelligence Quotient (PIQ) (R[exponent]2 = 0.7324, p = 0.0297), but not within non-atrophic hippocampus (V-SRT: R2 = 0.1013, p = 0.4424; PIQ: R[exponent]2 = 0.2303, p = 0.2288). These data suggest that elevated basal glutamate levels in the epileptogenic hippocampus may be implicated in the pathogenesis of hippocampal atrophy and may contribute to impaired cognitive functioning involving verbal memory and visual-spatial skills in patients with temporal lobe epilepsy.