Value-based management (VBM) is a business philosophy and management system for competing effectively in the global marketplace, based upon the inherent value, dignity and empowerment of each person particularly each employee, customer and supplier. Although VBM has been implemented in an organisation, the difficulty remains that the employees/workers do not necessarily understand the mechanics of VBM, or their actions in value creation. The main objective of this study is to determine if the employees/workers of the mining organisation understand the basic concepts of VBM, where it has been implemented and to determine whether or not VBM has been successfully implemented within a mining organisation. This was done by collecting data using a standardised questionnaire distributed among the mining company‟s employees. The results from the study indicated that VBM in general was successfully implemented but that lower lever employees is less informed on certain aspects of VBM. / MBA, North-West University, Potchefstroom Campus, 2014

Résumé: L’Imagerie par Résonance Magnétique fonctionnelle est devenue un des outils principaux pour mesurer l’activité cérébrale chez l’Homme de façon non-invasive. Le type de séquence plus fréquemment utilisé à ces fins est le signal dépendant du niveau d'oxvgène sanguin (BOLD signal) car il reflète les changements hémodynamiques associés à l’activité cérébrale et offr l’avantage d'être relativement facile à mesurer. Cependant, cette mesure est dépendante du niveau de désoxyhémoglobine, présent dans les veines. L'architecture structurelle de ces dernières varie considérablement d'une région du cerveau à l'autre et cela fait en sorte qu'il est ardu de savoir si les différences inter-régionales sont dues à des différences au niveau de l’activité neuronale ou de la structure vasculaire. C'est pour répondre à cette question que nous avons observé la relation entre les variations régionales de densité vasculaire (VAD) et l’amplitude du signal BOLD au repos et en présence d'un stimulus. Nous avons implémenté une méthode de segmentation des veines pour des images en pondération de susceptibilité (SWI). Nous avons également utilisé une méthode de segmentation des tissus (Morphométrie Basée sur les Voxels (VBM )) pour séparer les tissus et calculer une mesure de densité de matière. Nous avons trouvé qu'indépendamment de la taille des voxels, les variations régionales d'amplitude du signal BOLD au repos et du signal évoqué par une tâche sont mieux corrélées avec la VAD qu'avec la densité de matière grise. En utilisant un modèle linéaire général, nous avons observé qu'une grande partie des variations régionales au repos pouvait être modélisée par la VAD. En somme, nos résultats suggèrent que le signal BOLD au repos est intimement relié à la structure vasculaire. Utiliser la densité vasculaire afin de calibrer les mesures d'amplitude du signal BOLD au repos nous permettra d'interpréter de façon plus précise et d'obtenir de meilleures informations sur les différences observées entre plusieurs groupes de sujets et de patients. // Abstract: Functional Magnetic Resonance Imaging (fMRI) has become one of the primary tools used for non-invasively measuring brain activity in humans. For the most part, the blood oxygen level-dependent (BOLD) contrast is used, which reflects changes in heinodynamics associated with active brain tissue. The main advantage of the BOLD signal is that it is relatively easy to measure and thus is often used as a proxy for comparing brain function across population groups (i.e. control vs. patient). However, it is particularly weighted towards veins whose structural architecture is known to vary considerably across the brain. This makes it difficult to interpret whether differences in BOLD between cortical areas reflect true differences in neu-ral activity or vascular structure. We therefore investigated how regional variations of vascular density (VAD) relate to the amplitude of resting-state and task-evoked BOLD signals. To address this, we first developed an automated method for segmen-ting veins in images acquired with susceptibility weighted imaging (SWI), allowing us to visualize the venoms vascular tree across the brain. In 19 healthy subjects, we then applied Voxel-Based Morphometry (VBNI) to Ti-weighted images and compu-ted regional measures of gray matter density (GNID). We found that, independent of spatial scale. regional variations in resting-state and task-evoked fNIRI amplitude was better correlated to VAD compared to GRID. Using a general linear model (GLNI). it was observed that the bulk of regional variance in resting-state activity could be modelled by VAD. Taken together, our results suggest that resting-state BOLD signals are signifi-cantly related to the underlying structure of the brain vascular system. Calibrating resting BOLD activity by venous structure may result in a more accurate interpreta-tion of differences observed between cortical areas and/or individuals.

Value-based management (VBM) is a business philosophy and management system for competing effectively in the global marketplace, based upon the inherent value, dignity and empowerment of each person particularly each employee, customer and supplier. Although VBM has been implemented in an organisation, the difficulty remains that the employees/workers do not necessarily understand the mechanics of VBM, or their actions in value creation. The main objective of this study is to determine if the employees/workers of the mining organisation understand the basic concepts of VBM, where it has been implemented and to determine whether or not VBM has been successfully implemented within a mining organisation. This was done by collecting data using a standardised questionnaire distributed among the mining company‟s employees. The results from the study indicated that VBM in general was successfully implemented but that lower lever employees is less informed on certain aspects of VBM. / MBA, North-West University, Potchefstroom Campus, 2014

The human brain is a complex and powerful organ, directing every aspect of life from somatosensory and motor function to visceral responses to higher order cognition. Neurological and psychiatric disorders often disrupt normal functioning. While the clinical symptoms of such disorders are known, their biological underpinnings are not as clearly characterized. Structural neuroimaging is a powerful, non-invasive tool that can play a critical role in finding biomarkers of these illnesses. Currently, variations in pre-processing techniques yield inconsistent and conflicting results. As neuroimaging is a nascent branch of medical research, gold standards in imaging methodologies have not yet been established. Quantitatively validating and optimizing the way these images are preprocessed is the first step towards standardization. Voxel-based morphometry (VBM) is one technique that is commonly used to compare whole-brain structural differences between groups. Statistical tests are used to compare intensities of voxels throughout all brain scans in each group. In order to ensure that comparable voxels are being tested, the images must be fitted into a common space, which is done through image preprocessing. Spatial normalization to templates is an early pre-processing step that is executed unreliably as many options for both templates and normalization algorithms exist. To determine the effect variations in template usage may cause, we utilized a VBM approach to detect simulated lesions. Template performance was analyzed by comparing the accuracy with which the lesion was detected.

La sclérose latérale amyotrophique [SLA] est une pathologie idiopathique à issue fatale caractérisée par la dégénérescence progressive et sélective des motoneurones du système nerveux central et périphérique. La SLA n’est pas exclusivement identifiée comme une maladie de la voie pyramidale, mais considérée plus largement comme une pathologie neurodégénérative multisystème. L’étude des mécanismes posturaux dans cette population n’a pas fait l’objet d’une grande attention. Dans ce travail de thèse, une exploration en imagerie cérébrale multimodale (imagerie en tenseur de diffusion [DTI] et morphométrie basée sur le voxel [VBM]) est proposée chez des patients SLA avec instabilité posturale [AIP] et stables [SIP] en vue de vérifier l’intégrité morphologique et structurelle des régions corticales et sous-corticales posturales. La comparaison entre les sujets contrôles et les patients SLA a démontré une augmentation significative du volume de la substance grise au niveau du noyau caudé chez les patients stables (SIP vs contrôle p<0,001 ; SIP vs AIP p<0,01). L’évaluation structurelle a révélé une diminution de la fraction d’anisotropie [FA] au niveau de l’aire motrice supplémentaire [AMS] dans les deux groupes de patients par rapport aux contrôles (contrôle vs SIP p<0,05 ; contrôle vs AIP p<0,001). Au niveau du noyau caudé, le groupe AIP a présenté une diminution de la valeur de la FA par rapport aux sujets contrôles (p<0,001) et aux sujets SIP (p<0,05). Ainsi, ces résultats contribuent à une meilleure caractérisation et compréhension des atteintes corticales et sous corticales des régions qui interviennent dans la posture chez les patients SLA. / The Amyotrophic Lateral Sclerosis [ALS] is an idiopathic pathology with a fatal outcome. It is characterized by a progressive and selective degeneration of motor neurons in the central and peripheral nervous system. ALS is no longer exclusively identified as a disease of the pyramidal pathway, but it is considered more broadly as multisystem neurodegenerative pathology. However, the analysis of postural processes in these patients has not been well studied in the literature. Multimodal brain imaging (Diffusion Tensor Imaging [DTI] and Voxel Based Morphometry [VBM]) exploration was performed for ALS patients with postural instability [AIP] and without postural instability [SIP] to test the morphometric and structural integrity of postural cortical and subcortical regions. A significant increase of gray matter in caudate nucleus volume has been noticed for stable patients (SIP vs controls p<0.001, SIP vs AIP p<0.01). The structural evaluation revealed a decrease of the Fractional Anisotropy [FA] at the Supplementary Motor Area [SMA] level in both groups of patients compared to controls (controls vs SIP p<0.05, controls vs. AIP p<0.001). At the caudate nucleus, the AIP group showed FA value decrease compared to controls (p<0.001) and SIP subjects (p<0.05). Thus, these results would contribute to a better characterization and understanding of the cortical and subcortical impairments of the postural regions in ALS patients.

Long-term motor skill learning has been consistently shown to result in functional as well as structural changes in the adult human brain. However, the effect of short learning periods on brain structure is not well understood. In the present study, subjects performed a sequential pinch force task (SPFT) for 20 min on 5 consecutive days. Changes in brain structure were evaluated with anatomical magnetic resonance imaging (MRI) scans acquired on the first and last day of motor skill learning. Behaviorally, the SPFT resulted in sequence-specific learning with the trained (right) hand. Structural gray matter (GM) alterations in left M1, right ventral premotor cortex (PMC) and right dorsolateral prefrontal cortex (DLPFC) correlated with performance improvements in the SPFT. More specifically we found that subjects with strong sequence-specific performance improvements in the SPFT also had larger increases in GM volume in the respective brain areas. On the other hand, subjects with small behavioral gains either showed no change or even a decrease in GM volume during the time course of learning. Furthermore, cerebellar GM volume before motor skill learning predicted (A) individual learning-related changes in the SPFT and (B) the amount of structural changes in left M1, right ventral PMC and DLPFC. In summary, we provide novel evidence that short-term motor skill learning is associated with learning-related structural brain alterations. Additionally, we showed that practicing a motor skill is not exclusively accompanied by increased GM volume. Instead, bidirectional structural alterations explained the variability of the individual learning success.

No description available.

Recently, Magnetic Resonance Imaging (MRI) has found great traction in monitoring the effects of Caloric Restriction (CR) on the brain, specifically gray matter. However, there are no streamlined, simple pipelines in existence to analyze data generated from these kinds of MRI studies. Therefore, my hypothesis is two-fold: the first part being the development of a dynamic and straightforward image processing pipeline, which I have tailored to fit the unique needs of the CR data involved in this study. This data brings me to the second part of my hypothesis, which is to use that pipeline to highlight the decreased attenuation in grey matter induced by long-term CR. In order to test the second portion of my hypothesis, T1/MPRAGE scans were collected from 17 male Rhesus Macaques, half of which were maintained on a 30% reduced calorie diet for an average of 22 years, starting around age 3. Using this basis, the inherent properties of the MR images were exploited by the novel pipeline, and used to analyze whether or not CR reduces the attenuation of grey matter atrophy, with regards to aging

BACKGROUND: Migraine is a primary headache disorder that has a high prevalence and burden of disease throughout the world. Migraine symptoms include throbbing head pain, nausea, hypersensitivity to light, sound, and smell, and autonomic, cognitive, emotional, and motor disturbances. About a third of migraineurs have aura symptoms which are transient neurological symptoms with gradual onset before the migraine attack, visual disturbances, sensory loss, and/or communication impairment. The trigeminovascular system, central descending modulation, and brainstem descending modulation have been implicated in the pathophysiology of migraine. However, the exact neurovascular mechanism for migraine has not been determined. Several imaging techniques have been used to find structural and functional brain changes in migraineurs. OBJECTIVE: In order to further existing knowledge of migraine pathophysiology, structural brain differences were investigated using imaging between migraineurs and healthy individuals and differences within migraineurs. METHODS: Thirty-two patients with migraine (25 females) and 32 healthy control subjects (25 females) age-, ethnicity-, and gender-matched participated in our study. Magnetic resonance imaging (MRI) scans were collected from each participant. Then, voxel-based morphometry (VBM) was utilized to find any gray matter (GM) volume differences between migraine patients and controls. Also, VBM was performed in specific regions-of-interest (ROIs) to compare 11 migraine patients with aura (MA) and 11 migraine patients without aura (MO). RESULTS: A significant increase in regional gray matter volume difference was observed for migraine patients compared to control subjects in the intracalcarine gyrus of the visual cortex (corrected, p<0.05). In the VBM analysis of ROIs, the similarities between the MO and MA subjects included increases in the anterior cingulate cortex (ACC), hippocampus, insula, and intracalcarine cortex, along with decreases in the ACC and insula (uncorrected, p<0.05). MO subjects had decreases in the amygdala, hippocampus, intracalcarine cortex, and thalamus, but not in the MA subjects (uncorrected, p<0.05). The MA patients had increases in the amygdala and thalamus, but not in the MO patients (uncorrected, p<0.05). DISCUSSION: It can be concluded that the visual cortex is involved in the migraine mechanism since a large increase in GM volume difference was found in migraine, MO, and MA cohorts, as well as results from previous studies. Numerous GM volume changes in MO and MA cohorts reinforce evidence that particular brain regions are a part of migraine pathophysiology, but there were some regions that do not. Further research using imaging analysis and with larger study populations should be conducted to enhance our understanding of the migraine mechanism and differences that arise between migraine groups, so that diagnosis and treatment administration can be improved.

Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) are two neurodevelopmental disorders with distinct diagnostic criteria that often co-occur. Although both ASD and ADHD are associated with structural and functional brain abnormalities when compared to typically developing (TD) populations, it is necessary to disentangle the shared and specific abnormalities between these disorders, potentially underlying similarities and differences in their clinical and neurocognitive profiles. The aim of this thesis was to explore the shared and disorder specific functional and structural brain abnormalities between ASD and ADHD. For this purpose, the neural underpinnings of a group of children with ADHD, a group of children with ASD and a group of TD children aged 8 to 12 years old were compared using different neuroimaging techniques. In Chapter 2, the experimental sample included in this thesis was described using multiple clinical and neurocognitive measures. In the first study (Chapter 3), total and regional brain volumes were compared between groups, using voxel-based morphometry. The results of this study showed larger grey matter volume (GMV) in the left precuneus and decreased GMV in the right thalamus in the ADHD group compared to either the TD or the ASD groups, and increased GMV in the right precentral gyrus in the ASD group compared to either the ADHD or the TD groups. In the second study (Chapter 4), white matter microstructure was compared between groups using diffusion tensor imaging derived indices (fractional anisotropy [FA] and mean diffusivity [MD]). Reduced FA (i.e. reduced diffusion directionality) in the genu of the corpus callosum (CC) was found in the ASD group compared to either children with ADHD or TD children, whereas lower FA in the body of the CC was a shared feature between the ADHD and ASD groups. Finally, in the last study (Chapter 5), inhibition-related brain activation was compared between groups during the execution of an inhibition stop-signal task. In children with ADHD, successful inhibition was associated with right inferior parietal activation, whereas right frontal regions were activated in children with ASD. Between-group comparisons disclosed higher middle frontal activation in the ASD group compared to the ADHD or the TD groups. Taken together, our findings provide further evidence contributing to disentangle the shared and specific brain structural and functional abnormalities between ASD and ADHD. / Doctorat en Sciences psychologiques et de l'éducation / info:eu-repo/semantics/nonPublished