Rett syndrome (RTT) is a neurodevelopmental disorder that is caused by mutations in the X-linked gene MECP2 and results in cognitive impairment, epilepsy and motor dysfunction. Deletion or silencing of Mecp2 in the brain of mice recapitulates many of the main phenotypes of the disorder and has been fundamental in understanding the actions of MeCP2 although the precise molecular function remains unknown. MeCP2 is classically thought to have a role in repressing gene transcription through recruitment of histone deacetylase proteins. Studies have also shown that Mecp2 can be modified posttranslationally in response to neuronal activity. The aim of this thesis was to investigate the activity-dependent alterations in MeCP2 and the association this has with levels of acetylated histone proteins, a marker of active gene transcription thus gaining a better insight into how neuronal activity affects the function of MeCP2. Furthermore at the network level, a second objective was to characterise the effects loss of functional MeCP2 has on the regulation of network circuitry in the brain and in particular the development of epileptiform activities. To study this I focussed on the hippocampus in wild-type and Mecp2 mutant mice and in vivo administered the convulsant drug kainic acid (25mg/kg; IP) followed by seizure scoring and in vitro by application of various epileptogenic agents (kainic acid, bicuculline and 4-aminopyridine) to acute hippocampal slices. Having characterised the network properties, I then quantified protein alterations in phosphorylation of Mecp2, acetylated histone H3 and H4 and immediate early genes, c-Fos and Egr-1 in the hippocampus using western blot and quantitative immunohistochemistry techniques. Based on a modified seizure scale (eight stages with lower being less severe), administration of kainic acid in vivo to Mecp2-deficient male mice resulted in a higher seizure score (mean = 6 ± 0.7 vs. 4 ± 0.2 units in wild-type) and more rapid onset (77% of mice show seizures after 10 minutes compared to 5% of wild-type mice). Field recording data collected in vitro following application of kainic acid to hippocampal slice from Mecp2-deficient mice show a significant increase in gamma power oscillation (1059 ± 379µV2) compared to slices from WT mice (287 ± 178µV2) which had a lower mean power. Application of bicuculline revealed hippocampal slices from Mecp2-deficient mice had increased frequency of spontaneous epileptiform field events (1µM and 3µM bicuculline) and elevated duration of spontaneous and evoked epileptiform field events (10µM bicuculline). Similarly, 4-aminopyridine (4-AP) administration to hippocampal slices resulted in Mecp2-deficient mice displaying increased frequency of spontaneous field events (50µM 4-AP) and epileptic ictal-like events (88% of slices from Mecp2stop/y mice displayed these events compared to 43% of slices from WT mice). Furthermore there was an increase in spontaneous and evoked field events following application of 30µM and 10µM 4-AP. Western blot experiments using hippocampal extracts from WT and Mecp2-deficient male mice treated with the convulsant drug kainic acid or saline (vehicle control) revealed Mecp2 is highly phosphorylated at serine 421 (3.4 ± 0.5 fold, p< 0.01) upon induction of neuronal activity compared to saline controls but there was no change in histone H3 or H4 acetylated proteins. A complementary quantitative immunohistochemistry approach was used to assess variations in histone H3 or H4 acetylated proteins at the single cell level from heterozygous female mice (displaying a mosaic expression of Mecp2) treated with kainic acid or saline. These results revealed there was no difference in the levels of either acetylated histone H3 of H4 protein between Mecp2 positive and negative nuclei. However there was a clear cell-autonomous effect in terms of a 5% reduction in the nuclear volume of Mecp2-deficient cells. Quantification of immediate early gene signal in Mecp2+/- heterozygous female mice treated with kainic acid or saline using the same immunohistochemistry method showed there was no difference in the distribution of c-Fos intensities between Mecp2 positive and negative nuclei following any treatment. However there was a greater proportion of Mecp2-deficient nuclei (~20%) expressing c-Fos under saline control conditions and following neuronal activity. Furthermore there was a reduction in the percentage of Mecp2 negative nuclei in the top 25% of Egr-1 intensities in the CA1 following three hours of neuronal activity (33.5 ± 2.3% for Mecp2 negative nuclei and 19.1 ± 1.7% for Mecp2 positive nuclei). In summary my results show at the network level there is a reduction in seizure threshold and increase power of gamma oscillations in the hippocampus of Mecp2-deficient mice which could lead to a state of network hyperexcitability and switch activities from physiological oscillatory rhythms to more pathological ones. An imbalance in inhibitory neuron regulation could partially contribute to alterations in network excitability to overall promote epileptogenesis. At the cellular level I report that Mecp2 can become phosphorylated following induction of neuronal activity but this is not associated with alterations in global histone acetylation. Nonetheless Mecp2-deficient cells display a reduction in nuclear volume and have alterations in c-Fos and Egr-1 levels following induction of neuronal activity. Overall my data contribute to the understanding of how the presence or absence of MeCP2 affects network excitability and how in turn neuronal excitability affects MeCP2 phosphorylation, histone acetylation and the activation of immediate early genes.

N-Methyl-D-aspartate (NMDA) receptors are critically involved in synaptic transmission, neural development and various forms of neuronal plasticity including long-term potentiation (LTP) and long-term depression (LTD). They are also involved in the production of neuronal damage following excessive activation by glutamate released as a result of hypoxia or ischaemia. Each heteromeric receptor includes one or two NRl subunits, at least two of the four NR2A-D subunits and less usually the NR3AJB subunits. This study demonstrates that the putative NR2B subunit-containing NMDA receptor antagonist Ro 25-6981 potentiates the effects ofNMDA on rat hippocampal slices. The NR2A subunit antagonist PEAQX blocks the effects of NMDA alone and the potentiated response following Ro 25-6981 application. Furthermore, Ro 25-6981 was not neuroprotective as reported previously but unexpectedly precipitated excitotoxicity. The potentiating effect of Ro 25-6981 required around 20 minutes to become apparent, took a further 30 minutes to reach its maximum effect and was irreversible. It was not prevented by staurosporine (a broad-spectrum protein kinase inhibitor), okadaic acid (a potent inhibitor of the serine/threonine protein phosphatases types 1 and 2A) or anisomycin (a protein synthesis inhibitor). However, the potentiation was prevented by cyclosporin A (an inhibitor of Ca2+/calmodulin-dependent phosphatase 2B [calcineurin]). The results indicate that in an intact neuronal network, NR2B subunits tonically gate NR2A subunit-containing receptor function by a negative coupling mechanism involving ca1cineurin activation. NMDA receptor-dependent LTP induced by high frequency stimulation was prevented by PEAQX, an NR2A antagonist. Ro 25-6981 was unable to prevent L TP induction but was associated with a marginal reduction in the magnitude of LTP induced. There is evidence for the binding of homoquinolinic acid to an NMDAinsensitive novel binding site in the brain. This study investigated the pharmacology of homoquinolinate on the evoked field excitatory synaptic potential (fEPSP) recorded from the CAl area of rat hippocampal slices. Two NMDA receptor agonists, quinolinic acid 150/lM and homoquinolinic acid 2.5/lM, caused an approximately 50% inhibition of fEPSP slope. Paired-pulse studies suggested there might be a presynaptic component to this action that is independent of presynaptic adenosine Al receptor activation. The broad-spectrum EAA antagonist kynurenic acid and the NMDA receptor blockers 2-amino-5-phosphonopentanoic acid and dizocilpine could prevent the inhibition of fEPSP slope. None of these antagonists revealed any other NMDA-insensitive activity of homoquinolinic acid. The use of 2-carboxy-3-carboxymethylquinoline (CCMQ) to displace the reported NMDA-insensitive binding had no effect on either baseline fEPSP slope or the depression caused by homoquinolinic acid. It was also apparent that responses to homoquinolinic acid were blocked completely by the NR2A subunit-selective antagonist PEAQX, but not by the NR2B subunit-selective blocker Ro 25-6981. It was concluded that the novel binding site for homoquinolinic acid does not affect synaptic potentials in the hippocampus and that homoquinolinic acid appears to be a selective agonist at NMDA receptors that include the NR2A subunit. Although the NR2B agonist site may be maximally activated under normal conditions and therefore it is not possible to observe any additional effects upon fEPSP slope. This study next investigated the negative coupling between NR2B and NR2A subunit-containing receptors, combining the NR2A1B subunit selective agonist HQA with the NR2B and NR2A selective antagonists Ro 25-6981 and PEAQX. The negative coupling observed previously with applications of NMDA was also seen using HQA and QA. The potentiation of responses to HQA by Ro 25-6981 application was also associated with an enhancement of paired-pulse interactions. The subsequent application of PEAQX was able to block both the depression of fEPSP slope and the associated enhancement of paired-pulse interactions. The presence of a presynaptic element during applications of HQA alone and potentiated responses alike and the blockade of these effects by PEAQX suggests the NR2A subunit-containing NMDA receptor is responsible for the presynaptic effects acting either directly at presynaptic sites or indirectly at postsynaptic sites leading to the raising of a retrograde signal. The NR2B subunit in both its activated and antagonised state was associated with enhancements in paired-pulse interactions which suggest that it is not able to modulate directly the presynaptic element. However, whilst paired-pulse interactions are generally accepted to he presynaptic phenomena, it does not follow that postsynaptic effects cannot influence the appearance of changes in these interactions in field recordings. The absence of any observable difference between HQA, QA and NMDA results suggests that the NR2D subunit is not obviously involved in these processes.

Guillian-Barré Syndrome (GBS) is the world’s leading cause of neuromuscular paralysis occurring in serologically and pathogenically distinct forms. GBS is believed to have an autoimmune basis, where antibodies raised during antecedent infections (eg Campylobacter jejuni) cross-react with self antigens, exemplifying the process of molecular mimicry. These self-antigens are gangliosides, which are glycolipid structures enriched in peripheral nerve in specific membrane compartments termed lipid rafts. To date, successful murine models of anti-GD1a and anti-Gq1b ganglioside mediated neuropathy exist. Clinical evidence supports the involvement of anti-GM1 antibodies in nerve injury, however generation of anti-GM1 antibody mediated neuropathy models remain an enigma, and to date, the only successful model is based in Japanese rabbits. This thesis aims to address the controversies surrounding anti-GM1 antibody mediated neuropathy by utilising a panel of anti-GM1 antibodies of differing specificity, and explores how the stereometric interactions of GM1 with lipid raft species underpin the pathogenic potential of these antibodies.

One hundred and nine generalised anxiety disorder (GAD) patients, referred by their General Practitioners to a clinical psychology primary care service, were assigned to either Cognitive, Behavioural, Cognitive-behavioural, Placebo or Waiting List conditions. `Stress Control' large group therapy combined didactic therapy with a workshop model and emphasised the aim of turning patients into their own `therapists' in order to enable them to deal with present and future problems. Patients were thus encouraged to view Stress Control as an `evening class' rather than `group therapy'. Measures of treatment process and outcome were obtained mainly from self-report instruments. Follow-up data were collected at six months post-treatment. At post-therapy, all active therapy conditions and, against expectation, the Placebo condition had shown significant time within treatment group change. The active therapy conditions, and to a lesser extent, the Placebo condition, were significantly different to the Waiting List condition, which, overall showed no evidence of improvement. At follow-up the active therapy condition generally enhanced therapy gains while the placebo condition maintained therapy gains. Process measures did not, with the exception of self-statement change, differentiate between the groups. Noted variable response in the main analyses was somewhat explained by various sub-group analyses. There appeared to be little benefit in dividing patients into those who experienced panic and those who did not. There was some evidence that `matching' patients to therapy, i.e. cognitive responders to cognitive therapy was of value at post-therapy although differences generally disappeared at follow-up. Synchronous change was associated with enhanced performance. Finally, attempts to predict response to Stress Control by a comparison of responders and non-responders were attempted and the results assessed in terms of clinical as opposed to statistical significance. The results of the present study are discussed with reference to other treatment outcome studies and an attempt to produce a model to account for the similar effects found across treatment conditions. The implications of these findings and some suggestions for future research for GAD and other diagnostic categories are discussed.

Osteoarthritis (OA), depression and anxiety are common problems in primary care. OA coexisting with depressive and/or anxiety symptoms has detrimental consequences to the individual. To inform recognition and management of these important problems in primary care a better understanding of their coexistence is needed. A systematic review with meta-analysis was undertaken to determine the prevalence of depression and anxiety in adults with OA/joint pain in the community. Elevated anxiety symptoms were more common (45%) than depression symptoms (24%) in persons with OA joint pain. Sources of between study variance include methods of ascertainment and geographical location. A review of measurement properties of several recommended patient-reported depression and anxiety measures found evidence to support properties in some populations, but some critical properties warrant investigation in adults with OA in the community. A secondary data analysis was conducted for older consecutive primary care patients with musculoskeletal pain recruited to a cohort (n=443) of the PROGnostic Research study. Latent Class Growth Analyses identified clusters of individuals who exhibited different trajectories of anxiety and depression symptoms over a 12-month period: three anxiety and two depression symptom trajectories. In total, 56% and 63% of participants experienced persistent anxiety and depression symptoms respectively for at least 12 months. Pain characteristics and coping strategies were the most prominent risk factors for persistent anxiety and depression symptoms. With the aim of identifying individuals with sub- threshold persistent anxiety and depression symptoms, characteristics predisposing to symptoms persistence may be considered. A medical records review found that only half of all older musculoskeletal patients with persistent anxiety and depression symptoms have their mental health problems detected by their GP. Frequent consulters and those with more severe anxiety were more likely to be detected. This reinforces the need to recognise and manage OA coexisting with depression and/or anxiety by patients and health professionals alike.

The cerebellum receives information from the hindlimbs through several populations of spinocerebellar tract neurons. Although the role of these neurons has been established in electrophysiological experiments, the relative contribution of afferent fibres and central neurons to their input, their organization and mechanisms of control of transmission has only been estimated approximately so far. The present study aimed to investigate the input properties of four populations of spinocerebellar tract neurons: dorsal spinocerebellar tract neurons located in Clarke´s column (ccDSCT) and in the dorsal horn (dhDSCT) and ventral spinocerebellar tract (VSCT) neurons including spinal border (SB) neurons. There were three major aims: (1) to investigate the excitatory inputs to four types of spinocerebellar tract neurons in the cat and rat thoraco-lumbar spinal cord; (2) to analyze the inhibitory inputs to four types of spinocerebellar tract neurons in the cat and rat thoraco-lumbar spinal cord; (3) to determine the origin of excitatory and inhibitory inputs to four types of spinocerebellar tract neurons in the cat and rat thoraco-lumbar spinal cord. Two series of experiments were carried out. In the first series of experiments in cats, spinocerebellar tract neurons were identified electrophysiologically and labelled intracellularly with rhodamine-dextran and Neurobiotin. In the second series of experiments in rats, cells were labelled by retrograde transport of b-subunit of Cholera toxin (CTb) from the cerebellum. In addition, to address the third aim, reticulospinal (RetS) and corticospinal (CS) terminals were identified by anterograde transport of CTb from the caudal medulla and hindlimb sensory motor cortex respectively in rats along with labelling of spinocerebellar tract neurons by retrograde injection of Fluorogold in the cerebellum. Following this, immunohistochemistry was carried out. The first aim was achieved by utilizing the difference in the immunohistochemistry of glutamatergic terminals of peripheral afferents and of central neurons with vesicular glutamate transporters, VGLUT1 or VGLUT2, respectively. All SB neurons with dominating inhibitory input from the periphery possessed very few VGLUT1 contacts and remarkably higher numbers of VGLUT2 contacts. In VSCT neurons with excitatory primary afferent input, the number of VGLUT1 contacts was relatively high although VGLUT2 contacts likewise dominated. In contrast, DSCT neurons were associated with numerous VGLUT1 contacts; ccDSCT neurons with strong input from group I afferents had higher density of VGLUT1 contacts than dhDSCT neurons with major input from group II and cutaneous afferents. In order to fulfill the second aim, quantification of contacts formed by inhibitory axon terminals on spinocerebellar tract neurons along with excitatory terminals was carried out. Inhibitory axon terminals were characterised as either GABAergic, glycinergic or both GABAergic/glycinergic by using antibodies against vesicular GABA transporter (VGAT), glutamic acid decarboxylase (GAD) and gephyrin. Similarly, excitatory terminals were characterised by using combination of VGLUT1 and 2. The comparison revealed the presence of much higher proportions of inhibitory than excitatory contacts on SB neurons but similar proportions were found on VSCT, ccDSCT and dhDSCT neurons. In all types of cell, the majority of inhibitory terminals were glycinergic. The density of contacts was higher on somata and proximal in comparison with distal dendrites of SB and VSCT neurons but more evenly distributed in ccDSCT and dhDSCT neurons. To achieve the third aim, a series of immunohistochemical reactions was performed to characterize contacts that originate from proprioceptors, different types of interneurons and descending RetS and CS pathways. Among the four populations of spinocerebellar tract neurons, ccDSCT neurons had the highest proportion of contacts formed by VGLUT1 terminals double labeled with parvalbumin (PV) which indicated that majority of direct excitatory sensory inputs to ccDSCT neurons are derived from proprioceptors. A small proportion of excitatory and inhibitory contacts on these neurons originated from Calbindin/ Calretinin/ PV expressing neurons. Quantitative analysis revealed that SB and VSCT neurons have significantly higher numbers of appositions from VGLUT2 expressing RetS axon terminals than DSCT neurons. A small proportion of the RetS contacts on these neurons were VGAT positive. In contrast, DSCT neurons had higher numbers of appositions made by CS axon terminals in comparison to SB and VSCT neurons. The present findings provide a new basis for understanding the organization and functional connectivity of four populations of spinocerebellar tract neurons and strengthen previous indications of their functional differentiation. SB and VSCT neurons principally receive inputs from spinal and supraspinal neurons although direct input from primary afferents is also stronger in VSCT neurons. DSCT neurons have major direct input from primary afferents and also to some extent from the CS pathway but monosynaptic inputs from proprioceptors dominated in ccDSCT neurons and dhDSCT neurons have mixed proprioceptive and low threshold cutaneous afferent input.

In studies on the pathophysiology of the autoimmune neuropathy, Miller Fisher syndrome (MFS), monoclonal antibodies to the disialosyl epitopes on GQ1b, GT1a and GD3 gangliosides have been produced. Antibodies to these complex gangliosides are thought to be crucial in the pathogenesis of MFS. These antibodies have recently been shown to produce complement dependent, glial and/or neuronal injury at mouse neuromuscular junctions (NMJs). Three antibodies (EG1, LB1 and R24) were identified as producing selective terminal Schwann cell (TSC) injury whilst sparing neuronal membranes at NMJs in BALB/c and C57BL/6 mouse strains in a dose dependent manner. These changes occur in the absence of observable acute physiological or morphological changes to the nerve terminal, suggesting that TSC injury or loss has no major short-term influence on synapse function. Having compared the suitability of two common ex vivo muscle preparations for use in characterisation studies, TSC selective antibodies were compared, and EG1 was identified as most suitable for further investigations on the role of the TSC in mammalian NMJ function and as a possible disease target in MFS. The effect of this antibody when combined with normal human serum as a source of complement in ex vivo hemidiaphragm preparations was independent of complement regulators DAF1 and CD59a. Cell specific promoter sequences have been used to produce a mouse line that expresses green-fluorescent protein (GFP) in TSCs, and cyan-fluorescent protein (CFP) in axons (CK mouse). Live imaging techniques were used to study the acute and chronic effects of EG1 mAb mediated, complement dependent glial injury in this system. It is shown that TSC injury is characterised by loss of GFP staining, occurring within 20 minutes of complement exposure. Repopulation of the NMJs with GFP-positive cell bodies is first evident at day 2. The origin of these returning Schwann cells is discussed, and three possible sources are considered – the last myelinating Schwann cell, non-myelinating Schwann cells lying more proximally in the peripheral nervous system, and muscle stem cells. At day 7, the number of GFP-positive cell bodies seen at the NMJ is higher (7-12 per NMJ) than prior to antibody exposure (3-5 per NMJ). This process of enhanced repopulation is not dependent on an intact axon as it is retained following axotomy. At 3 months, minor remodelling of the NMJ is seen, and is more pronounced at one year. Repeat antibody exposure within 48 hours does not injure returning processes, or delay repopulation. Instead, extra-junctional TSC processes are formed, with associated axon sprouts in the absence of gross terminal axon injury. Anti-GQ1b containing serum from a MFS patient is shown to induce murine TSC death in a similar manner to murine monoclonal antibodies described previously. This suggests that TSCs are a potential new disease target in human disease if the ganglioside profile of mouse and human TSCs is equivalent. Ganglioside distribution and antibody binding are examined on a series of human muscles. These studies demonstrate for the first time that components of the human NMJ are potentially susceptible to anti-ganglioside antibody mediated injury, by virtue of their ganglioside profile. This study suggests that TSCs may be a previously unrecognised site of immune-mediated nerve injury. It also describes a new technique for observing chronic TSC injury and recovery in an in vivo mouse model system, which could be used for human disease modelling.

Many spinal cord injuries (SCI) are incomplete, variable numbers of spared fibres passing the lesion level and supporting some residual function below the injury. One approach to improving function following injury is to develop therapies that maximise the potential of these spared fibres. The aim of the work in this thesis was to investigate the spontaneous plasticity that occurs in spinal cord pathways following injury and then determine whether olfactory ensheathing cell (OEC) transplants or treatment with antibodies blocking the function of the myelin inhibitors Nogo and MAG could enhance this plasticity. An electrophysiological approach was used to investigate these questions in rats which were subjected to a lesion of the dorsal columns at the C4/5 segmental level. This lesion interrupts the main component of the corticospinal tract which descends in the ventromedial dorsal column and also interrupts the ascending collaterals of sensory fibres from forelimb nerves. In this study, changes in the function of both of these pathways were assessed by recording cord dorsum potentials (CDPs) after stimulation in the pyramids (corticospinal activation) or of the radial nerve (sensory fibre activation). To enable plasticity in the corticospinal system to be investigated a method was developed for maximally activating the corticospinal projection on one side of the pyramids, whilst avoiding activation of the opposite pyramid and structures surrounding the pyramids. It was found that this could be achieved by careful positioning of bipolar stimulating electrodes. Before investigating the effect of potential plasticity inducing agents, the degree to which plasticity occurs in the absence of treatments was first assessed in F344 rats. The function of corticospinal and sensory pathways was compared in normal animals, acutely lesioned animals, and at 1 week and 3 months after a dorsal column lesion. Corticospinally-evoked CDPs above the lesion were not altered following an acute lesion but were larger in 1 week and 3 month dorsal column lesioned animals than in normal animals. The increase in amplitude was similar in both lesioned animal groups. This suggests that plasticity occurs at the intact connections formed by corticospinal fibres axotomised more distally, that it occurs within a week of the lesion and persisits for at least 3 months. Corticospinally-evoked CDPs were almost abolished below an acute dorsal column lesion and remained of minimal amplitude 1 week after lesioning. However, there was some recovery of CDPs between 1 week and 3 months. This suggests plasticity either at the connections formed by spared fibres of the minor non-dorsal column components of the corticospinal tract or in propriospinal pathways originating above the lesion. This plasticity has a longer time-course than that at the connections of axotomised fibres above the lesion. Plasticity of the connections formed by larger diameter sensory fibres in the radial nerve was also seen below the level of the dorsal column lesion. This had a similar time course to the plasticity of corticospinal connections above the lesion CDPs being larger both 1 week and 3 months after injury compared to normal animals. A modest enhancement of transmission in both corticospinal and sensory systems therefore occurred following a dorsal column lesion. To investigate whether OEC transplants enhance plasticity after spinal cord injury, OECs were transplanted such that they became distributed within the spinal cord for several mm either above or below the lesion. Electrophysiological methods were then used, as above, to investigate whether transmission in the corticospinal and sensory fibre systems following a dorsal column lesion was improved in transplanted animals compared to 3 month survival animals. However, corticospinal actions rostral to the lesion were not enhanced by OEC transplants above the lesion and sensory transmission caudal to the lesion was not enhanced by cells below the lesion. OEC transplants are therefore unlikely to support recovery by promoting plasticity in the spinal cord after injury. To investigate whether antibodies designed to block the function of the myelin inhibitors Nogo and MAG would enhance plasticity following spinal cord injury, antibodies were delivered intrathecally via implanted osmotic minipumps over a period of six weeks following a dorsal column lesion. Vehicle treated and normal animals were investigated for comparison. Placement of the cannula and/or delivery of vehicle alone was found to have a detrimental effect on corticospinal actions above the lesion when compared to normal animals. Treatment with an anti-Nogo antibody (GSK577548) raised against a human Nogo-A fragment and targeting the amino-Nogo terminal was found to enhance transmission of corticospinal actions both above and below the dorsal column lesion. Corticospinal actions above the lesion were significantly greater than in the vehicle treated controls but did not exceed those in normal animals because of the detrimental effect of the intrathecal cannulae/vehicle treatment. Transmission at the terminals of sensory afferent fibres below the level of the lesion was also enhanced by anti-Nogo treatment. In this case the actions of sensory pathways were significantly greater than those in both vehicle treated and normal animals. The fact that enhanced transmission occurs on the ‘wrong side’ of the lesion to be explained by axonal regeneration and the sensory transmission is enhanced over normal, strongly suggests that anti-Nogo induces plasticity in spinal pathways. In contrast, treatment with the anti-MAG antibody (GSK249320A) had no effect on either corticospinal or sensory-evoked activity in the spinal cord above or below the lesion, CDPs evoked by these pathways being comparable to that in vehicle treated controls. Anti-MAG does not appear to induce plasticity but may have neuroprotective actions which cannot be adequately tested in this lesion model. The results show that both corticospinal and sensory fibre systems show modest spontaneous plasticity following a dorsal column lesion. Plasticity at the terminations of axotomised fibres occurs relatively rapidly (within one week) while plasticity in spared systems occurs more slowly. This spontaneous plasticity does not appear to be enhanced by transplants of OECs, so that improvements in spinal cord function previously demonstrated in transplanted animals are probably due to a neuroprotective mechanism. The results obtained using function blocking antibodies targeting myelin inhibitors suggest that anti-Nogo but not anti-MAG treatment may enhance plasticity in the spinal cord after injury. This observation adds to the accumulating evidence that interfering with Nogo-A signalling may be a useful approach for improving function after spinal cord injury.

Thesis Overview Psychogenic nonepileptic seizures (PNES) can be defined as paroxysmal events that resemble epileptic seizures, without being associated with either abnormal electrical activity of the brain or primary physiological disturbances otherwise. It is estimated that about 10% of new presentations seen in an epilepsy clinic, and up to 30% of patients with intractable epilepsy will eventually be diagnosed as having PNES (Benbadis & Hauser, 2000). Attributing a specific ‘cause’ to PNES is conceptually and clinically contentious but it seems reasonable to say that they represent a physical expression of psychological distress involving behaviour that the patient finds difficult or impossible to control or disavows as being intentional. Most patients with PNES are initially thought to have epilepsy and treated with antiepileptic drugs (AED), sometimes for many years. Up to 40% of patients are inappropriately maintained on AEDs after the diagnosis of PNES has been established. As such, rather than being intrinsic to the condition, the widely reported poor outcomes associated with PNES may be substantially confounded by continued inappropriate medical management and iatrogenic harm. Withdrawing or continuing antiepileptic medication in patients with PNES could have important physical and psychological consequences, which may affect the prognosis of the attack disorder. If this is the case, manipulating medication following the diagnosis of PNES may have a role in the management of this disorder. The work contained in this thesis aims to explore some aspects of the effects that continuing or withdrawing AED has on the course and outcome of PNES. Following an initial general overview on the subject of PNES (chapter 1), a systematic review of the literature is presented in chapter 2; the conclusion being a lack of good quality and reliable evidence for the effects of AED treatment in patients with PNES and a need for further original research in this area. The rationale and programme of research is presented in chapter 3 Chapter 4 presents the results of a large observational study to establish the feasibility and safety of supervised AED withdrawal in patients with an established diagnosis of PNES. Only 3 of the 78 patients included reported a new type of event requiring the reintroduction of AED, and no serious medical events were reported. The study therefore shows that, with appropriate diagnostic investigations and surveillance during follow-up, withdrawal of AED can be achieved safely in patients with PNES. A randomised controlled trial presented in chapter 5 aims to evaluate the potential therapeutic effect of AED withdrawal. Of the 25 subjects recruited, 14 were randomised to immediate withdrawal (IW) and 11 to delayed withdrawal (DW). Patients randomised to IW had a significant reduction in the use of emergency treatment for PNES, and a lower proportion was found to be using emergency services. The IW group also had a sustained reduction of attacks throughout the study and by 18 months post-diagnosis 50% were attack free as compared with 27% in the DW group. The results of this exploratory trial suggested a possible therapeutic effect of AED withdrawal, with a sustained reduction of attacks following the withdrawal of medication, coupled with a significant reduction in health care utilisation and no evidence of any deterioration. The last original paper presented in chapter 6 investigates the longer term psychosocial outcome of PNES with an observational study of the 25 patients included in the RCT. This study reports a significant improvement in some psychological measures; particularly in illness representations and mood, as well as for some measures of social adjustment. The evidence presented in these three studies (chapter 4, 5 and 6) suggests that a clear delivery of the diagnosis of PNES, followed by AED withdrawal, is safe and has possible beneficial effects on the clinical and psychosocial outcome of PNES. In particular medication withdrawal in and of itself appears to be a helpful concomitant in the successful removal of an inappropriate label of label of epilepsy, reduces the potential for iatrogenic harm, may help patients to shift towards a more psychologically-based explanation, and is associated with positive psychosocial outcomes. Finally, chapter 7 gives a summary of the main findings as well as discussing methodological limitations of the current research. The clinical implications of the evidence from this body of work are also discussed, as well as possible avenues for future research in the field.

No description available.