1,720,988 research outputs found
Cardiorespiratory exercise improves white matter microstructure and processing speed in childhood brain tumour survivors
No full textTumours of the central nervous system are the most common form of malignant brain tumour in the paediatric population. Childhood brain tumour survivors exhibit long-term impacts of radiation treatment on both brain structure and function, negatively impacting their quality of life. We employed a clinical intervention trial to investigate the effects of exercise on improving white matter microstructure and cognitive functions within this population. Using diffusion tensor imaging and a battery of cognitive tests, we have shown that 12-weeks subsequent to a 12-week (carryover effect) exercise program, improved microstructure is displayed within the inferior longitudinal fasciculus. The carryover effect of exercise also led to improved processing speed. Furthermore, exercising within a group setting was indicative of better WM and processing speed outcomes. Exercise improves brain microstructure and processing speed, and should be employed as a post-treatment intervention for childhood brain tumour survivors to ameliorate deficits caused by past radiation therapy.M.A
Cardiorespiratory exercise improves white matter microstructure and processing speed in childhood brain tumour survivors
No full textTumours of the central nervous system are the most common form of malignant brain tumour in the paediatric population. Childhood brain tumour survivors exhibit long-term impacts of radiation treatment on both brain structure and function, negatively impacting their quality of life. We employed a clinical intervention trial to investigate the effects of exercise on improving white matter microstructure and cognitive functions within this population. Using diffusion tensor imaging and a battery of cognitive tests, we have shown that 12-weeks subsequent to a 12-week (carryover effect) exercise program, improved microstructure is displayed within the inferior longitudinal fasciculus. The carryover effect of exercise also led to improved processing speed. Furthermore, exercising within a group setting was indicative of better WM and processing speed outcomes. Exercise improves brain microstructure and processing speed, and should be employed as a post-treatment intervention for childhood brain tumour survivors to ameliorate deficits caused by past radiation therapy.M.A
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The Impact of Exercise on Cognition and Neural Activity Under Varying Cognitive Demands in Children Treated for Brain Tumours
No full textChildren treated with cranial radiation for brain tumours exhibit substantial deficits in information processing (IP) over time. Slower IP speed appears to underlie the inability to recruit cognitive resources required to meet greater task demands and is related to aberrant brain function. Exercise has been shown to improve IP speed and enhance neural activity. We assessed the influence of exercise on IP speed and the underlying functional mechanisms during increasingly demanding conditions by examining visual-motor reaction-time (RT) and regional neural activation during varying task loads using MEG. Immediate and longer-term changes in RT and local neural activity in 4 frequency bands was investigated. After exercise, patients demonstrated stable visual-motor RT under varying task demands and decreased high gamma (60-100Hz) power when task load was minimal. Our findings suggest exercise mitigates declines in IP speed and enhances underlying functional mechanisms under varying cognitive demands in children treated for brain tumours.M.A
White Matter Microstructure and Emotional Functioning in Children Treated for Posterior Fossa Tumours
No full textChildren treated for brain tumours that arise in the posterior fossa (PF) experience lifelong cognitive and emotional difficulties, and exhibit white matter (WM) damage. This thesis combined diffusion tensor imaging (DTI), eye-tracking and standardized measures of cognitive and emotional functioning in children treated for PF tumours and typically developing children, to: 1) characterize outcomes related to decreases in treatment intensity, 2) objectively evaluate emotional functioning, and 3) examine the associations between WM microstructure and emotional functioning. It was found that treatment with the lowest intensity craniospinal irradiation protocol spared WM in the temporal lobe of children treated for malignant PF tumours. In addition, patients treated on lower intensity protocols had largely preserved cognitive, social and affective functioning. However, novel eye-tracking tasks designed to evaluate emotional functioning uncovered some remaining deficits; children treated for PF tumours had difficulty recognizing facial emotions despite attending to the faces, and difficulty regulating their initial attention away from emotional faces. Notably, this eye-tracking measure of emotion regulation was associated with emotional control in daily life. The current work also revealed that relations between WM microstructure and emotional functioning can diverge in the injured and uninjured brain; WM predicted facial emotion recognition in typically developing children only, whereas WM was associated with emotion regulation in patients only. In a field dominated by findings that characterize negative sequelae, this work highlights the possibility of favourable outcomes for PF tumour patients who are eligible for treatment with lower intensity protocols. Despite these positive outcomes, subtle emotional functioning deficits not captured by standardized questionnaires persist. To better understand how emotional processes are altered in children treated for PF tumours, novel objective measures are required. This thesis detailed one such behavioural marker to evaluate emotion regulation, using eye-tracking technology, and characterized an oculomotor response that may warrant interventional follow-up.Ph.D
Placebo Controlled Double Blind Crossover Trial of Metformin for Brain Repair in Children Treated with Cranial Radiation for Brain Tumours
No full textOBJECTIVES: Cranial radiation results in neuronal insult and cognitive impairment in brain tumour survivors (BTS). Metformin increases neurogenesis and improves memory in mice. We conducted a pilot double-blind randomized controlled crossover trial to examine the effects of metformin versus placebo on hippocampal and white matter (WM) volume, and cognitive processes in BTS. METHODS: Twenty four participants were randomly assigned to complete 12-week cycles of Metformin (A) and Placebo (B) in either an AB or BA sequence. Assessment at baseline and immediately following treatment included: (a) structural MRI to obtain hippocampal subfield and WM volume, and (b) cognitive testing. Linear mixed modelling was used to measure changes in outcome measures with respect to treatment, cycle, and carryover. FINDINGS: Treatment and carryover effects were observed, suggesting ongoing effects up to 22 weeks following treatment. CONCLUSION: Metformin may be effective for normalizing brain structure and cognitive processes in BTS.M.A
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Neuropsychological Outcome following Cranio-spinal Radiation in Medulloblastoma Patients: A Longitudinal Analysis of Predictors
No full textMedulloblastoma is the most common malignant central nervous system (CNS) tumor in childhood. The cranio-spinal radiation (CSR) required to treat this disease results in long-term cognitive and neurologic impairments. Medulloblastoma was recently categorized into four genetic subgroups (WNT, SHH, Group 3, and Group 4). This study examined neuropsychological and intellectual functioning in 91 medulloblastoma patients (41 Group 4; 20 Group 3; 18 SHH; 12 WNT) following treatment, and examined the impact of several medical, treatment and demographic factors on functioning over time. Longitudinal growth curve analyses revealed hydrocephalus most clearly predisposes to poor neuropsychological functioning. Results also indicate medulloblastoma subgroups have heterogeneous intellectual outcomes following treatment. All subgroups experience intellectual declines following treatment; however, comparing between subgroups revealed Group 4 performs most poorly, and Group 3 has the best overall intellectual outcome. Lastly, qualitative analyses suggest treatment with a larger CSR dose may contribute to poor intellectual functioning.MAS
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