Cortical oscillatory dysrhythmias in visual snow syndrome: a magnetoencephalography study

Visual Snow refers to the persistent visual experience of static in the whole visual field of both eyes. It is often reported by patients with migraine and co-occurs with conditions like tinnitus and tremor. The underlying pathophysiology of the condition is poorly understood. Previously we hypothesised, that visual snow syndrome may be characterised by disruptions to rhythmical activity within the visual system. To test this, data from 18 patients diagnosed with visual snow syndrome, and 16 matched controls, were acquired using magnetoencephalography. Participants were presented with visual grating stimuli, known to elicit decreases in alpha-band (8-13Hz) power and increases in gamma-band power (40-70Hz). Data were mapped to source-space using a beamformer. Across both groups, decreased alpha power and increased gamma power localised to early visual cortex. Data from the primary visual cortex were compared between groups. No differences were found in either alpha or gamma peak frequency or the magnitude of alpha power, p>0.05. However, compared with controls, our visual snow syndrome cohort displayed significantly increased primary visual cortex gamma power, p=0.035. This new electromagnetic finding concurs with previous functional MRI and PET findings suggesting that in visual snow syndrome, the visual cortex is hyper-excitable. The coupling of alpha-phase to gamma amplitude within the primary visual cortex was also quantified. Compared with controls, the visual snow syndrome group had significantly reduced alpha-gamma phase-amplitude coupling, p<0.05, indicating a potential excitation-inhibition imbalance in visual snow syndrome, as well as a potential disruption to top-down “noise-cancellation” mechanisms. Overall, these results suggest that rhythmical brain activity in primary visual cortex is both hyperexcitable and disorganised in visual snow syndrome, consistent with this being a condition of thalamocortical dysrhythmia

Assessing the number of users who are excluded by domestic heating controls

This is the pre-print version of the Article. This Article is also referred to as: "Assessing the 'Design Exclusion' of Heating Controls at a Low-Cost, Low-Carbon Housing Development". - Copyright @ 2011 Taylor & FrancisSpace heating accounts for almost 60% of the energy delivered to housing which in turn accounts for nearly 27% of the total UK's carbon emissions. This study was conducted to investigate the influence of heating control design on the degree of ‘user exclusion’. This was calculated using the Design Exclusion Calculator, developed by the Engineering Design Centre at the University of Cambridge. To elucidate the capability requirements of the system, a detailed hierarchical task analysis was produced, due to the complexity of the overall task. The Exclusion Calculation found that the current design placed excessive demands upon the capabilities of at least 9.5% of the UK population over 16 years old, particularly in terms of ‘vision’, ‘thinking’ and ‘dexterity’ requirements. This increased to 20.7% for users over 60 years old. The method does not account for the level of numeracy and literacy and so the true exclusion may be higher. Usability testing was conducted to help validate the results which indicated that 66% of users at a low-carbon housing development could not programme their controls as desired. Therefore, more detailed analysis of the cognitive demands placed upon the users is required to understand where problems within the programming process occur. Further research focusing on this cognitive interaction will work towards a solution that may allow users to behave easily in a more sustainable manner

White matter developmental trajectories associated with persistence and recovery of childhood stuttering

Stuttering affects the fundamental human ability of fluent speech production, and can have a significant negative impact on an individual’s psychosocial development. While the disorder affects about 5% of all preschool children, approximately 80% of them recover naturally within a few years of stuttering onset. The pathophysiology and neuroanatomical development trajectories associated with persistence and recovery of stuttering are still largely unknown. Here, the first mixed longitudinal diffusion tensor imaging (DTI) study of childhood stuttering has been reported. A total of 195 high quality DTI scans from 35 children who stutter (CWS) and 43 controls between 3 and 12 years of age were acquired, with an average of three scans per child, each collected approximately a year apart. Fractional anisotropy (FA), a measure reflecting white matter structural coherence, was analyzed voxelâ wise to examine group and ageâ related differences using a linear mixedâ effects (LME) model. Results showed that CWS exhibited decreased FA relative to controls in the left arcuate fasciculus, underlying the inferior parietal and posterior temporal areas, and the mid body of corpus callosum. Further, white matter developmental trajectories reflecting growth rate of these tract regions differentiated children with persistent stuttering from those who recovered from stuttering. Specifically, a reduction in FA growth rate (i.e., slower FA growth with age) in persistent children relative to fluent controls in the left arcuate fasciculus and corpus callosum was found, which was not evident in recovered children. These findings provide first glimpses into the possible neural mechanisms of onset, persistence, and recovery of childhood stuttering. Hum Brain Mapp 38:3345â 3359, 2017. © 2017 Wiley Periodicals, Inc.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137362/1/hbm23590.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137362/2/hbm23590_am.pd

Neuromagnetic beta band abnormalities in stuttering during the perception and production of rhythm

Theoretical thesis.Bibliography: pages 305-337.1. General introduction -- 2. Speech acquisition -- 3. A review of normal speech production -- 4. Systematic review of neuroimaging studies of developmental stuttering from 1996 to 2015 -- 5. The need to study children who stutter -- 6. Beta band, timing and stuttering -- 8. Dynamic causal modelling of beta band in adults -- 9. Sensorimotor synchronisation in adults who stutter -- 10. Neuromagnetic beta band responses of typically developing children to isochronous intervals -- 11. Abnormal time course of low beta modulation in non-fluent preschool children: a magnetoencephalographic study of rhythm tracking -- 12. General discussion.Recent work provides evidence that stuttering can be considered a disorder of timing. A separate body of literature suggests that the neural oscillations within the canonical beta band (12-30Hz) are important for timing and rhythm. The present thesis aimed to link these two areas of research by using magnetoencephalography(MEG) to examine beta band responses to the perception and production of rhythm in adults and children who stutter (AWS and CWS respectively).I first review the neurological substrates associated with normal speech production in order to build a foundation for understanding impaired speech production. Secondly, I review the past ten years of neuroimaging research on developmental stuttering to gain an overall state of the literature and discuss the need to focus research on CWS. Thirdly, I present multimodal neuroimaging evidence for the view that thecore deficit in developmental stuttering is a disorder of timing. Fourthly, I detail the role of the beta band in timing and rhythm as it applies to stuttering. The experimental chapters then follow.The first experiment used MEG in conjunction with dynamic causal modelling (DCM) to measure the effective connectivity between the auditory and motor cortices in the beta band during synchronised and syncopated finger tapping in AWDS. The second experiment aimed to find differences in neuromagnetic beta band activity betweenAWS and AWDS when they are engaged in paced and unpaced finger tapping.The third experiment aimed to assess the feasibility of recording beta band activity from children who do not stutter (CWDS) when listening to trains of rhythmic sounds (390ms, 585ms and 780ms) in order to later assess this in CWS. The fourth and final experiment compared beta band responses of CWS and CWDS while passively listening to either a rhythmic (450ms) or less rhythmic trains of sounds (SOA varying between 300 and 600ms).The results of the first experiment in AWDS showed that both synchronisation and syncopation tapping was driven by auditory feedback in the beta band as evidenced by the winning model containing connections propagating from the auditory to the motor cortex. It also revealed that the difference between synchronisation and syncopated tapping was best explained by connections going from the motor cortex to the auditory cortex and vice versa suggesting that it placed greater demands on motor activity. The second experiment established that AWS exhibit greater betaband modulation compared to AWDS during synchronised but not syncopated fingertapping in the left motor cortex. The third experiment established that CWDS tolerated listening to repetitive trains of sound for a period of about 30 minutes relatively well. It also showed that CWDS exhibit a beta band (12-15Hz) response similar to what has previously been observed in adults. The fourth and final experiment confirmed these results in another sample of CWDS. Interestingly, however, the CWS compared to CWDS in this study showed a beta band response between12-15Hz that was out of phase with the beta band response of CWDS. Overall, Ishow that AWS and CWS exhibit abnormalities in the beta band and build upon the idea that stuttering is related to deficits in timing.Mode of access: World wide web1 online resource (xxxii, 370, 2, 2, 2 pages) illustrations (some colour

Sureties in terms of the National Credit Act 34 of 2005

The purpose of this dissertation is to examine sureties in terms of the National Credit Act 34 of 2005 (hereafter "NCA"). The main research question contemplated in this dissertation is whether the full protection of the NCA should be extended to all natural persons standing surety for the debts of individuals or entities by way of entering into suretyship agreements. It further identifies problem areas within the provisions of the NCA in this regard, and ultimately aims to offer some prospective solutions thereto. Suretyship agreements are critical to credit providers in order to restrict risks when granting credit. The NCA introduces new forms of protection for consumers in South Africa, setting out the purpose of the NCA in the preamble and section 3 thereof. In view of the aims of the NCA it is submitted that the major objective of consumer credit legislation is to minimise malpractices, establish equal bargaining power between parties to a credit agreement and most importantly the protection of private individual consumers. However, not all agreements are governed by the NCA, and only certain specified credit agreements fall within the ambit of the Act. Therefore, the NCA's field of application is extremely important to consumer legislation, because it defines the extent of protection that consumers are entitled to. This dissertation investigates the definition and characteristics of a suretyship, and examine whether the definition of a suretyship is compatible with the definition of a credit guarantee in terms of the NCA. Furthermore, this dissertation investigates whether all natural person sureties are being treated equally by the law, amongst others, arguing that the present situation is unconstitutional as it unreasonably and unfairly discriminate against this group of natural person sureties in particular. Finally, two sets of conclusions are drawn together in this dissertation. Firstly, the analysis of the ordinary suretyship compared to a credit guarantee envisaged in section 8(5) of the Act. Thus, ascertaining whether a suretyship agreement is a credit agreement in terms of the NCA. Secondly, the question of whether the Act's full protection should be extended to all natural person sureties.Mini Dissertation (LLM)--University of Pretoria, 2017.Mercantile LawLLMUnrestricte

Analysis of the regulation of a family of proteins--MERM : moesin, ezrin, radixin & merlin--in vitro and in vivo

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Biology, 1999.Includes bibliographical references.by Etchell Ann Cordero.Ph.D