Background: Cardiovascular disease is the leading cause of mortality in patients with Chronic Kidney Disease (CKD). Vascular calcification is a significant contributor to cardiovascular mortality in CKD. Klotho is a 130kDa transmembrane protein with cardiovasculo-protective properties and also functions as a co-factor for the phosphatonin, fibroblast growth factor (FGF)-23 at the kidney. FGF-23 levels rise in CKD despite progression of accelerated vascular calcification (VC). There are currently conflicting data on whether FGF-23 may exhibit direct vasculo-protective effects in CKD. Methods and results: In this study, we describe for the first time endogenous Klotho expression in human arteries and human aortic smooth muscle cells (HASMCs). We show that CKD is a state of vascular Klotho deficiency promoted by chronic circulating stress factors, including pro-inflammatory, uremic and disordered metabolic conditions. Mechanistic studies demonstrated that Klotho knockdown potentiated the development of accelerated calcification through a Runx2 and myocardin-SRF dependent pathway. Klotho knockdown studies further revealed that vascular cells are a Klotho-dependent target tissue for FGF-23. FGF-23 mediated cellular activation of p-ERK, p-AKT and cellular proliferative effects, which were abrogated following Klotho knockdown. We next showed that vascular Klotho deficiency driven by pro-calcific stressors could be restored by vitamin D receptor (VDR) activators, in vitro and further confirmed using human arterial organ cultures from CKD patients, in vivo. Furthermore, restoration of Klotho by vitamin D receptor (VDR) activators conferred HA-SMCs FGF-23 responsive and unmasked its anticalcific effects. Conclusions: Chronic metabolic stress factors found in CKD promote vascular Klotho deficiency. Mechanistic studies revealed a bi-functional role for local vascular Klotho, first as an endogenous inhibitor of VC and second, as a co-factor required for vascular FGF-23 signalling. Furthermore, VDR activators can restore Klotho expression and unmask FGF-23 anti-calcific effects.

Polycystic Ovary Syndrome (PCOS) is the most common reproductive and endocrine disorder in females during their reproductive life. The syndrome is characterized by a constellation of symptoms and signs including menstrual disturbance, hyperandrogenism and polycystic ovaries. Other features of PCOS include obesity, metabolic syndrome, insulin resistance and an increased risk of developing diabetes mellitus and cardiovascular disease. Recently, PCOS has been recognized as a low grade inflammatory condition. Several inflammatory markers have been found to be raised in PCOS, such as interleukin-6, tumour necrosis factor-alpha and Interleukin-18. Low grade inflammation may potentially produce an insulin resistant state and promote the development of atherosclerosis. Insulin sensitzers such as metformin and pioglitazone have been shown to have a favourable effect not only on the symptoms of PCOS, but also on the hormonal and metabolic parameters in those subjects. In my thesis I primarily focussed on IL-18, B cells activating factor (BAFF), and the hepatokine, Fetuin-A, all linked to insulin resistance. IL-18 has a strong affinity towards its natural inhibitor, IL-18 binding protein (BP) and binding of IL-18 to IL-18 BP results in neutralization of IL-18, and consequently reduced free IL-18; the active form of the molecule. I have shown that PCOS women have a higher free IL-18, with hyperinsulinaemia the main factor that determines IL-18 in vitro. Furthermore, I have shown that Pioglitazone treatment for 12 weeks decreased both the total and free IL-18 in PCOS women. The reduction of IL-18 was accompanied by an improvement in IR. On the other hand, metformin treatment for six months failed to improve insulin sensitivity and did not influence IL-18 levels. BAFF, a novel adipokine, was studied in PCOS subjects, and I found lower BAFF levels in this cohort of patients. In vivo, BAFF correlated negatively with androgens, and in vitro work revealed that androstenedione as a negative regulatory factor for BAFF production Fetuin-A also known human protein α2-Heremans-Schmid glycoprotein, is a known natural inhibitor for insulin and abundantly expressed and secreted by the liver; fetuin-A has been suggested to act as a link between obesity, insulin resistance and MS. The circulating levels of Fetuin A are increased in women with PCOS, which is more pronounced when associated with MS. Metformin decreases Fetuin A in vivo, and also decreases both the expression and secretion of Fetuin A from HepG2 cells.

Dicarbonyl glycation - particularly glycation by methylglyoxal (MG) - is an important type of spontaneous damage to the proteome. Proteins that are susceptible to glycation by MG with consequent functional impairment are called collectively the dicarbonyl proteome. Methylglyoxal-derived advanced glycation endproducts (AGEs) are abundant in vascular tissues and are thought to contribute to the development of vascular complications of diabetes. Dicarbonyl stress is the imbalance of reactive dicarbonyls and anti-glycation defences leading to increased AGEs. Previous studies have shown that the concentration of MG is increased in human microvascular endothelial cells in vitro incubated in a model of hyperglycaemia. The glyoxalase system is an anti-glycation defence in all cells that metabolises MG and thereby suppresses MG-mediated protein damage. Overexpression of Glo1 decreased the intracellular levels of MG. Recently it has been reported that primary aortic endothelial cells incubated under high glucose concentration in vitro showed decreased activity of Glo1. The aim of this investigation was to improve the understanding of protein damage in vascular disease in diabetes, -focusing on protein damage by MG in vascular endothelial cells in hyperglycaemia. The effect of high glucose concentrations on formation and metabolism of methylglyoxal was studied in human vascular endothelial cells in vitro. The ability of a Glo1 inducer, resveratrol (RSV), to counter dicarbonyl stress in human endothelial cells in vitro was also assessed. In vivo effects of Glo1 deficiency and over expression on dicarbonyl glycation were also studied in mouse model of diabetic vascular disease. The results show that methylglyoxal concentration is increased by 2 - 3 fold in culture medium and ca. 109% inside human vascular endothelial cells during culture in model hyperglycaemia which is returned to normal by RSV treatment. In addition, the flux of formation of D-lactate, the terminal product of MG metabolism by the glyoxalase system, is increased by 30% in endothelial cell cultured in model hyperglycaemia in vitro is also prevented by RSV. Furthermore, cellular activity of glyoxalase 1 and protein content is decreased by 20 - 30% with high glucose culture due to increased ubiquitination of Glo1 in human vascular endothelial cells in vitro suggesting increased proteolysis of Glo1. RSV also protected the decrease in Glo1 activity in these cells. However the increased formation of AGEs free adducts observed in high glucose conditions were not corrected with RSV but the level of MG-damaged proteins in cells was protected. Disturbance of methylglyoxal metabolism in an experimental model of diabetic vascular disease, Glo1 deficient mice at 20 weeks did not show any increase in dicarbonyl glycation of aortal collagen. However at 35 weeks the major MG and glyoxal derived AGE - MG-H1 and CML - were significantly increased possibly due to deterioration in metabolic resistance to dicarbonyl stress with age or/and decreased turnover in vascular collagen. Overexpression of Glo1 restricted to sites of the proendothelin promoter (endothelial cells and smooth muscle cells) in mice was unable to decrease aortal dicarbonyl glycation and atherosclerosis. This study reveals that the defence against dicarbonyl glycation is decreased in endothelial cells in high glucose in vitro and the flux of formation of methylglyoxal is increased. Induction of Glo1 expression may contribute to health benefits of RSV and Glo1 inducers may protect against the development of vascular complications in diabetes.

Diabetes mellitus is a major, life-threatening worldwide disease wherein pathological complications include increased risk of infection and cardiovascular disease. The hallmark of diabetic disease is elevated plasma glucose. Within the immune system and vasculature, host-pathogen and regulatory host-host interactions can operate through binding of microbial or host oligosaccharides by proteins of the C-type lectin family. A number of these proteins recognise oligosaccharides rich in mannose and fucose: monosaccharide units with similar chemical structures to glucose. This raises the possibility that the high glucose conditions in diabetes affect immunological protein-oligosaccharide interactions via competitive inhibition. Mannose binding lectin, soluble recombinant DC-SIGN and DC-SIGNR, were tested for binding to high-mannose and high-fucose ligands in the presence of high glucose concentrations, typical of diabetes, via surface plasmon resonance and affinity chromatography. Complement activation assays were conducted in the presence of high glucose. Analysis of DC-SIGN and DCSIGNR expression in a range of tissues and cells was studied via immunohistochemistry and selective functional proteomics. High glucose greatly inhibited mannose binding lectin protein (MBL), DC-SIGN and DCSIGNR binding to high-mannose glycoprotein ligands, and binding of DCSIGN to a fucosylated ligands (ABO blood group trisaccharides) was abrogated in high glucose. Complement activation via the lectin pathway was inhibited in high glucose and also in high concentrations of trehalose, a nonreducing sugar with glucoside stereochemistry. Immunohistochemistry revealed DC-SIGN staining in adipose, brain and renal tissue, consistent with expression on dendritic cells. Selective functional proteomic analyses in leucocytes and placenta revealed thrombospondin-1 and pappalysins 1 and 2 as candidate DC-SIGN ligands with implications in vascular disease and pregnancy complications. Furthermore the carbohydrate recognition domains of DC-SIGN and DC-SIGNR were prepared in 15N stable isotope medium and analysed via solution NMR spectroscopy, providing a gateway to understanding the molecular dynamics of these lectins. Additional analyses of novel glycopolymers highlighted the potential therapeutic properties of these compounds. This thesis shows that high glucose disrupts C-type lectinmediated protein-oligosaccharide interactions, providing new mechanistic perspectives for the susceptibility to infectious and inflammatory disease in diabetes. The mechanisms involved are noncovalent, competitive, selective and reversible; in contrast to the broadly indiscriminate, covalent, widespread and irreversible glycation of proteins. The thesis illuminates a set of valuable new tools and ligand networks that will benefit diabetes and immunological research.

Electroencephalogram (EEG) based Brain Computer Interfaces (BCIs) have been successfully developed to help patients with motor disabilities but with retained cognitive abilities. In this thesis, the BCI techniques are developed for patients with severe brain injuries such as those in minimally conscious states (MCS) and vegetative states (VS). In 2006, neuroimaging based volitional imagery paradigms akin to the ones used for the development of motor imagery based BCIs revealed that a VS patient could produce neural responses indistinguishable from those produced by a healthy subject. The work presented in the thesis is inspired by this revelation and presents first attempts to develop electrophysiology based objective bedside methods to detect awareness in disorders of consciousness. The benefit of electrophysiology based methods is that they are able to register the response from the brain immediately and provide far better time resolution than imaging. As many patients either cannot undergo a fMRI scan or do not have access to it, it is believed that long term benefits to quality of life for this patient group can be better achieved at the bedside by an electrophysiological solution. In order to achieve the objectives, EEG data is collected using two BCI approaches: volitional imagery and event related potentials (ERPs) through rare/odd presentation of a target stimulus amongst a sequence of stimuli which produces high amplitude EEG wave after 300ms of its occurrence, this is called P300. Four different variants of volitional paradigms of 'imagine playing tennis' and 'spatial navigation' are used to collect data from 19 healthy subjects and the P300 speller is used to collect data from 5 healthy subjects, two MCS and two VS patients. In the case of imagery data, a channel selection scheme based on classifier performance, which also evaluates the contribution of each channel to the classification process, is used. This scheme is developed from the offline analysis of a benchmark dataset from the BCI competition III. The comparative results of algorithms for BCI imagery data analysis (time domain parameters (TDP), adaptive autoregressive (AAR) and bandpower (BP) for feature extraction and linear discriminant analysis (LDA), support vector machines (SVM) for classification) is presented to determine the feasibility of using these paradigms with patients. Consistent performance accuracy Figures for classification, in the range of 80-90%, are achieved showing that volitional tasks are distinguishable through EEG. A combination of AAR and LDA outperformed the other combinations of algorithms. The actively contributing channels, in achieving these classification results, are used to create EEG signatures for the volitional tasks. The EEG signatures indirectly signify the areas of brain activation for each of the volitional tasks and are found to be comparable to those obtained from neuroimaging. The validation of techniques is performed using a two class, 64-channel electrocorticogram (ECoG) dataset and initial data exploration was performed using principal component analysis (PCA). The derivative of the linear least fit polynomial was used as features and 64% classification was achieved on the unlabelled test data with multi layer perceptron (MLP) as the benchmark mechanism. Ten channels which actively contributed to the classification process were selected using genetic algorithms (GAs), thereby reducing the dimensionality, an important benefit when analysing multichannel, multi-trial datasets. Feature extraction techniques, which can combine spatial and temporal information such as common spatial patterns (CSP), were evaluated and 86% trials were classified correctly using MLP classification. The validation of classifier performance based channel selection produced six channels of interest, the bipolar combinations of which produced a best accuracy of 86% classification with AAR features and LDA classifier and also with TDP features and SVM classification. The P300 data recorded from the patients was investigated for a reproducible P300 response to the target letters. This is achieved by signal averaging and the analysis of square of Pearson‘s correlation coefficient (r-square). Clearly identifiable differential responses to the target letters were observed for three patients. It is believed that with auditory addition to the stimulus presentation in the stimulation procedure, training and consistency of responses, a tool for an objective method of diagnosis and assistive communication could be developed for this patient group. The BCI technology had not been used for the cognitively impaired patient groups such as MCS and VS, hence, the results of this work are new and contribute to bridging the gap between the core BCI research and its applications for patients. The objective measures of awareness developed through EEG based BCI methods will help to reduce the misdiagnosis rate, which is 43% for this patient group. The findings of the work presented in this thesis can be used to further develop an assistive communication tool for patients in this group.

Two approaches were used to assess resistant starch fermentation: 1) Measurement of plasma acetate and breath hydrogen. The major source of acetate in blood in the fed state is from colonic fermentation of carbohydrate. Plasma acetate has been used previously for studying fermentation of dietary fibre. Breath hydrogen is also commonly used but there are several disposal routes for hydrogen making it a poor marker for slowly fermented carbohydrates like RS. 2) Use of stable isotope tracers (13C). Although 13C enriched starch has been used to measure digestion, this is the first study to use 13C-labelled pea flour to measure fermentation in human adults. Fermentation of raw potato starch was monitored by serial plasma acetate and breath hydrogen. Five subjects were fed 100g raw potato starch (34; RS2) in the evening and breath hydrogen and plasma acetate were measured throughout the next day. Guar gum was used as a fermentable standard. Breath hydrogen and plasma acetate increased within approximately 11 hours, peaking within 14 hours compared with 4 and 6 hours after guar gum. There was much variation in breath hydrogen and plasma acetate responses. The rise in plasma acetate occurred at a very different time to breath hydrogen. In most, but not all subjects, the rise and peak of plasma acetate happened earlier than for breath hydrogen. This makes it difficult to use these measurements for studies of slowly fermented carbohydrates. An alternative approach using stable isotopes was therefore explored. Starchy foods had to be enriched with 13C during their starch deposition phase. Peas and potatoes were chosen because of their potential high RS and faster rate of growth. A high 13C enrichment of pea flour was gained by photosynthetic incorporation of 13CO2. Pea plants (Baccara variety) were grown and when pods began to form, placed in a 13CO2 enriched environment in polypropylene bags sealed air-tight. 250 ml of 13CO2 were added and the bags filled to capacity with room air. The plants were incubated for 6 days on two occasions separated by 1 week. Peas were allowed to ripen under normal conditions and were harvested and dried to form flour. The mean atom % excess of 13C in once labelled pea flour was 2.4% and for twice labelled peas was 8.64%. Chemical and enzymatic attempts to separate the components of the pea flour were not totally successful, but it was clear that the label was distributed throughout the pea flour. Potatoes were not successfully labelled (mean atom % excess of 13C 0.71%) because the plants could not tolerate a long time in the polypropylene bags. The digestibility of starch in the pea flour, measured using the Englyst method (in vitro model), was 14.4% rapidly digestible starch, 63.7% slowly digestible starch and 21.9% RS. 300 ms labelled-pea flour incorporated into biscuits was fed to six subjects and breath samples taken every 30 mins for up to 34 hours (with a short gap when subjects were asleep) and analysed for hydrogen and 13CO2 enrichment. The appearance of 13CO2 in breath showed a complex of three peaks. The first peak occurred over the first 6 hours and should correspond to digestion and absorption of rapidly digestible and slowly digestible starch fractions in the small intestine.

Aims: The primary aim of this randomised-controlled trial was to evaluate the effect of an exercise consultation (experimental condition) compared with standard exercise information (control condition) on maintenance of physical activity six and 12 months following completion of a phase III hospital-based exercise programme. Secondary aims included assessing the effect of an exercise consultation compared with exercise information on physiological and psychological variables at six and 12 months. Conclusions: This study demonstrated that the exercise consultation was more effective than exercise information in maintaining self-reported physical activity for 12 months after completion of a phase III exercise programme. However, the change in CSA accelerometer readings over the 12-month study period did not parallel the significant decrease in self-reported physical activity observed in the control group. The exercise consultation was not effective in maintaining exercise capacity for 12 months after completion of phase III. Significant decreases in peak VO2 from baseline to 12 months were observed in both groups. In contrast, an improvement in the VO2 at the lactate threshold, which is an index of submaximal endurance capacity, was recorded in the experimental group compared to the control group from baseline to follow-up. Finally, the exercise consultation had no significant effect on processes of exercise behaviour change, lipid profile and psychological function. These variables were normal at baseline and were maintained over the study period in both groups. The results of this study demonstrate that the exercise consultation may be an effective intervention for maintaining physical activity after completion of phase III hospital-based exercise programmes. The exercise consultation is a minimal intervention that could be delivered by physiotherapists to patients at the end of phase III or by British Association of Cardiac Rehabilitation (BACR) trained exercise instructors to patients in phase IV.

Hypertension is the major risk factor for coronary disease worldwide. Primary hypertension is idiopathic in origin but is thought to arise from multiple risk factors including genetic, lifestyle and environmental influences. Secondary hypertension has a more definite aetiology; its major single cause is primary aldosteronism (PA), the greatest proportion of which is caused by aldosteroneproducing adenoma (APA), where aldosterone is synthesized at high levels by an adenoma of the adrenal gland. There is strong evidence to show that high aldosterone levels cause adverse effects on cardiovascular, cerebrovascular, renal and other systems. Extensive studies have been conducted to analyse the role that regulation of CYP11B2, the gene encoding the aldosterone synthase enzyme plays in determining aldosterone production and the development of hypertension. One significant regulatory factor that has only recently emerged is microRNA (miRNA). miRNAs are small non-coding RNAs, synthesized by a series of enzymatic processes, that negatively regulate gene expression at the posttranscriptional level. Detection and manipulation of miRNA is now known to be a viable method in the treatment, prevention and prognosis of certain diseases. The aim of the present study was to identify miRNAs likely to have a role in the regulation of corticosteroid biosynthesis. To achieve this, the miRNA profile of APA and normal human adrenal tissue was compared, as was the H295R adrenocortical cell line model of adrenocortical function, under both basal conditions and following stimulation of aldosterone production. Key differentially-expressed miRNAs were then identified and bioinformatic tools used to identify likely mRNA targets and pathways for these miRNAs, several of which were investigated and validated using in vitro methods. The background to this study is set out in Chapter 1 of this thesis, followed by a description of the major technical methods employed in Chapter 2. Chapter 3 presents the first of the study results, analysing differences in miRNA profile between APA and normal human adrenal tissue. Microarray was implemented to detect the expression of miRNAs in these two tissue types and several miRNAs were found to vary significantly and consistently between them. Furthermore, members of several miRNA clusters exhibited similar changes in expression pattern between the two tissues e.g. members of cluster miR-29b-1 (miR-29a-3p and miR-29b-3p) and of cluster miR-29b-2 (miR-29b-3p and miR-29c- 3p) are downregulated in APA, while members of cluster let-7a-1 (let-7a-5p and let-7d-5p), cluster let-7a-3 (let-7a-5p and let-7b-5p) and cluster miR-134 (miR- 134 and miR-382) are upregulated. Further bioinformatic analysis explored the possible biological function of these miRNAs using Ingenuity® Systems Pathway Analysis software. This led to the identification of validated mRNAs already known to be targeted by these miRNAs, as well as the prediction of other mRNAs that are likely targets and which are involved in processes relevant to APA pathology including cholesterol synthesis (HMGCR) and corticosteroidogenesis (CYP11B2). It was therefore hypothesised that increases in miR-125a-5p or miR- 335-5p would reduce HMGCR and CYP11B2 expression. Chapter 4 describes the characterisation of H295R cells of different strains and sources (H295R Strain 1, 2, 3 and HAC 15). Expression of CYP11B2 was assessed following application of 3 different stimulants: Angio II, dbcAMP and KCl. The most responsive strain to stimulation was Strain 1 at lower passage numbers. Furthermore, H295R proliferation increased following Angio II stimulation. In Chapter 5, the hypothesis that increases in miR-125a-5p or miR-335-5p reduces HMGCR and CYP11B2 expression was tested using realtime quantitative RT-PCR and transfection of miRNA mimics and inhibitors into the H295R cell line model of adrenocortical function. In this way, miR-125a-5p and miR-335-5p were shown to downregulate CYP11B2 and HMGCR expression, thereby validating certain of the bioinformatic predictions generated in Chapter 3. The study of miRNA profile in the H295R cell lines was conducted in Chapter 6, analysing how it changes under conditions that increase aldosterone secretion, including stimulation Angiotensin II, potassium chloride or dibutyryl cAMP (as a substitute for adrenocorticotropic hormone). miRNA profiling identified 7 miRNAs that are consistently downregulated by all three stimuli relative to basal cells: miR-106a-5p, miR-154-3p, miR-17-5p, miR-196b-5p, miR-19a-3p, miR-20b- 5p and miR-766-3p. These miRNAs include those derived from cluster miR-106a- 5p/miR-20b-5p and cluster miR-17-5p/miR-19a-3p, each producing a single polycistronic transcript. IPA bioinformatic analysis was again applied to identify experimentally validated and predicted mRNA targets of these miRNAs and the key biological pathways likely to be affected. This predicted several interactions between miRNAs derived from cluster miR-17-5p/miR-19a-3p and important mRNAs involved in cholesterol biosynthesis: LDLR and ABCA1. These predictions were investigated by in vitro experiment. miR-17-5p/miR-106a-p and miR-20b-5p were found to be consistently downregulated by stimulation of aldosterone biosynthesis. Moreover, miR-766-3p was upregulation throughout. Furthermore, I was able to validate the downregulation of LDLR by miR-17 transfection, as predicted by IPA. In summary, this study identified key miRNAs that are differentially-expressed in vivo in cases of APA or in vitro following stimulation of aldosterone biosynthesis. The many possible biological actions these miRNAs could have were filtered by bioinformatic analysis and selected interactions validated in vitro. While direct actions of these miRNAs on steroidogenic enzymes were identified, cholesterol handling also emerged as an important target and may represent a useful point of intervention in future therapies designed to modulate aldosterone biosynthesis and reduce its harmful effects.

Understanding the brain in both health and disease is of critical practical importance as well as fundamental scientific interest. The acute neural tissue slice is a widely used experimental preparation, it facilitates treatments and measurements not practical in vivo while preserving a largely connected network representative of the true in vivo structure. This thesis presents the development of two techniques for the study of the acute neural tissue slice, both particularly well suited to the study of epilepsy, followed by an application of one of these techniques. A slice chamber is presented that allows extended regions of a tissue slice to be exposed, in isolation, to changes in ionic environment or pharmacological manipulation, readily providing an entirely in vitro model of focal epilepsy. Secondly, a transformation is derived that converts the slow dynamics of the intrinsic optical signal (IOS) associated with neuronal activity both in vivo and in vitro to the form of the associated local field potential, allowing the advantages of the IOS to be exploited while mitigating the primary disadvantage - the lack of direct correspondence between the IOS and the associated network dynamics. Finally a study is presented that employs the transformation of the IOS to facilitate a quantitative characterisation of the spatio-temporal dynamics of adenosine release in response to electrographic seizure activity.

Parkinson’s disease (PD) is one of the most prevalent movement disorders in the world. A clinical hallmark of PD is the appearance of proteinaceous Lewy Bodies throughout the brain that are predominantly formed from aggregation of the presynaptic protein alpha-Synuclein (αSyn). Increasing evidence, however, suggests that the soluble annular αSyn oligomers, formed during early stages of aggregation, are more toxic and pathologically relevant than the larger fibrils which form at later stages of aggregation. The underlying mechanism(s) through which αSyn oligomers exert their toxicity is still largely unknown. This thesis investigates how the toxic nature of αSyn oligomers may affect the electrophysiological properties of neurons. A population of soluble oligomers, termed mOligomers, were isolated from the early stages of in vitro aggregation. In addition, a separate oligomeric species was recovered from the fragmentation of large fibrils; termed fOligomers. Structural characterisation of these two species revealed them to be similar in size and ring-like in shape but showed subtle differences in their secondary structure. Purified, oligomeric αSyn was injected directly into the somata of thick-tufted layer 5 pyramidal neurons in mouse neocortical brain slices during whole-cell patch clamp recording and compared to the effects of equivalent concentrations of αSyn monomer. Using a combined experimental and modelling approach, a wide range of neuronal parameters were extracted and demonstrated oligomer-specific changes in neuronal electrophysiology that were time dependent. Perfusion with αSyn oligomers markedly reduced input resistance, enhanced the current required to trigger an action potential and reduced the firing rate illustrating a reduction in excitability that has the potential to impact both neural circuitry and cognitive output.