Please read the abstract in the 00front part of this document. / Dissertation (MA (Communication Pathology))--University of Pretoria, 2007. / Speech-Language Pathology and Audiology / unrestricted

M.A. (Clinical Psychology) / Research on lateralization has been replicated in many countries of Europe, the American states and the Asiatic states. The research findings on language functions verify the occurrence of cerebral dominance or lateralization in these various races. In the South African context, language lateralization has been studied among the whites and the asiatics, but no study to date has been done among the various black population groups. The specific aim of the present study was to fill this void by researching language lateralization in a young mail Tsonga population, ascertaining the effect of the degree of language lateralization on various language abilities (reading, writing, spelling, vocabulary)...

This study was designed to examine whether normal information processing does engage both hemispheres of the brain regardless of sensory channel (i.e., auditory or visual), and whether an opportunity for dual encoding (verbal and visual) was advantageous for patients with unilateral brain damage. It compared memory for verbal material presented in the visual and auditory modalities among three groups: right hemisphere brain damaged stroke patients (RBD), left hemisphere brain damaged stroke patients (LBD), and neurologically intact control subjects.

No description available.

No description available.

There are currently many statements about the effects of hemispheric specialization of the brain upon children's cognitive processing and therefore, upon content or modes of instruction. Before educators can accept or even test these statements, it is important to devise easy-to-use measures of hemispheric functioning and to study their relationship to established measures of achievement and linguistic and cognitive development. Current research in brain functioning has indicated that conjugate-lateral eye movement direction (the direction in which a person looks while thinking) can be a sensitive indicator of which cerebral hemisphere is initially activated. The central purpose of this investigation was to analyze the effects of the stimulus characteristics of reflective questions of verbal and spatial nature on the conjugate-lateral eye movement (CLEM) behavior of right-handed children from fourth, fifth, and sixth grades. A major objective was to determine whether data on children’s CLEM responses would better support a model of characteristic individual differences or a model of differentiation by question type. The testing instrument devised for this purpose was the Reflective Questions Test (RQT) which included both Verbal and Spatial subtests. In an experimenter-facing-subject paradigm with a sample of 60 (30 boys, 30 girls), conjugate-lateral eye movement was found to be easily observable and question type was found to influence the direction of eye movement, thus supporting a differentiation by question type model. Verbal questions elicited significantly more rightward CLEMs than spatial questions and spatial questions elicited significantly more leftward CLEMs than verbal questions fn the sample studied. No significant sex differences were found. These results seem to be consistent with the neuropsychological theory that once hemispheric specialization has occurred with normal right-handed children, the left hemisphere mediates language functions and the right hemisphere mediates spatial functions. Examining the number of directionally appropriate CLEM responses, a two-way analysis of variance (verbal and spatial question type by grade level) yielded no main or interaction effects. The results suggest that although children in grades four, five, and six tended to gaze in different directions while responding to verbal than while responding to spatial questions, the rate of responses appropriate to the question (gazing in the direction predicted) was no greater for verbal than for spatial questions. Further, the means for question types were almost identical across grade levels for CLEM responses to verbal and to spatial questions, supporting a no-change model of neuropsychological function, which contends that within the later childhood years, hemispheric specialization is well developed. The Reflective Questions Test was found to have high inter-rater reliability (.94) and temporal stability (.78). These results indicate that the RQT produced reliable and stable results for the sample studied and support the appropriateness of the RQT for future refinement and use in educational research of this type. Correlations of the RQT with other measures of linguistic and cognitive development, and educational ability were found to be nonsignificant. These results suggest that hemispheric activation as indexed by the RQT at this age range may be largely independent of measures traditionally associated with school performance. The results of this investigation have provided normative data on normal right-handed children, thereby providing a comparative basis for future research with children of the same age from other populations such as the learning disabled. / Ed. D.

M.A. / The study aims to determine whether statistically significant differences exist between boys with attention deficit hyperactivity disorder (ADHD) and boys without ADHD with regard to hemispheric language lateralization and the laterality of various modalities (handedness, eyedness and footedness). According to the literature, a possible connection exists between abnormal lateralization patterns and various developmental disorders (Corballis, 1983; Geschwind & Behan, 1982; Hiscock, 1988, McFarland, 1981; Turkewitz, 1988). Lateralization in the current study refers to hemispheric language specialisation, hand dominance, foot dominance and eye dominance. In most people these functions are lateralized to the one side of the body by the age of seven (Kalat, 1995; Kolb & Whishaw, 1996). They typically manifest a dominant left hemisphere for language and a right-sided dominance for handedness, footedness and eyedness. The result is a dominant left hemisphere, due to the left side of the brain controlling the right side of the body. Some children however manifest insufficient or poor lateralization of these functions. For purposes of this study, it would imply that the functions of language specialisation, handedness, footedness and eyedness are not all lateralized to one side of the body. A possible connection between this poor or insufficient lateralization and ADHD might exist. According to the DSM IV (1997) the essential feature of ADHD is a persistent pattern of inattention and/or hyperactivity/impulsivity that is more frequent and severe than is typically observed in individuals at a comparable level of development. Some of these symptoms causing impairment must have been present before age seven, although many individuals are only diagnosed after the symptoms have been present for a number of years. Impairment resulting from the symptoms should be present in at least two settings, for example, at school and at home. Clear evidence must exist of interference with developmentally appropriate social, academic, or occupational functioning. An empirical study was conducted in order to compare the hemispheric language specialisation, handedness, eyedness and footedness of the various subjects. The subjects consisted of 20 ADHD boys (8 -12 years) who met the criteria of the DSM IV and 20 Non-ADHD boys (8-12 years) without any learning problems. Various interference variables were controlled in the selection of the subjects (see section 5.2.3) Kimura's dichotic listening technique was used to measure hemispheric language specialisation and the Harris-test for Lateral Dominance was used to measure handedness, eyedness and footedness. Wilks's lambda, Pearson's chi-quadrant and Student's t-tests were used during statistical analysis of data. Results indicated statistically significant differences between ADHD boys and non-ADHD boys with regard to hemispheric language specialisation, handedness and footedness. Overall, the results indicated that the ADHD boys are not as strongly lateralized as the non-ADHD boys. The non-ADHD boys showed a stronger left hemispheric language specialisation, right hand dominance and right foot dominance. No statistical differences were recorded with regard to eyedness. The current study provides possible theoretical support for the theory that a connection exists between poor or insufficient lateralization patterns and children with ADHD. However, the study only focused on white boys between the ages of 8-12 years. Further studies involving different age groups, cultures and gender are recommended.

This study examined the effectiveness of Mind Mapping (a diagram of the structure of ideas in an associative manner, using graphics, color and key words) as a note-taking device in a training course in a large, high-tech corporation, as compared to traditional note-taking. The population for this study consisted of personnel employed by a major high-tech firm, that had voluntarily registered for a Mind Mapping training class. The effect of Mind Mapping was measured by the pre-test and post-test of the control and experimental groups.

Large scale functional brain networks, defined by synchronized spontaneous oscillations between spatially distinct anatomical regions, are essential to brain function and have been implicated in disease states, cognitive capacity, and many sensing and motor processes. In this work, we sever the corpus callosum in the rodent model to determine if structural connectivity (specifically the primary interhemispheric pathway) organizes and influences bilateral functional connectivity and brain-wide spatiotemporal dynamic activity patterns. Prior to the callosotomy work, resting state brain networks were evaluated using blood oxygen level dependent (BOLD) and cerebral blood volume (CBV) magnetic resonance imaging contrast mechanisms, and revealed that BOLD and CBV provide highly similar spatial maps of functional connectivity; however, the amplitude of BOLD connectivity was generally stronger. The effects of extended anesthetic durations on functional connectivity were also evaluated revealing extended isoflurane anesthetic periods prior to the switch to dexmedetomidine attenuates functional activity for a longer duration as compared to a shorter isoflurane paradigm. We also observed a secondary significant evolution of functional metrics occurring during long durations of dexmedetomidine use under the currently accepted and refined dexmedetomidine sedation paradigm. Taking these previous findings into account, we moved forward with the callosotomy study. Functional network integrity was evaluated in sham and full callosotomy groups using BOLD and electrophysiology. Functional connectivity analysis indicated a similar significant reduction in bilateral connectivity in the full callosotomy group as compared to the sham group across both recording modalities. Spatiotemporal dynamic analysis revealed bilaterally symmetric propagating waves of activity in the sham data, but none were present in the full callosotomy data; however, the emergence of unilateral spatiotemporal patterns became prominent following the callosotomy. This finding suggests that the corpus callosum could be largely responsible for maintaining bilateral network integrity, but non-bilaterally symmetric propagating waves occur in the absence of the corpus callosum, suggesting a possible subcortical driver of the dynamic cascading event. This work represents a robust finding indicating the corpus callosum's influence on maintaining integrity in bilateral functional networks.

Une lésion corticale hémisphérique peut entrainer des troubles distincts en fonction du côté de la lésion : troubles du langage pour l'atteinte de l'hémisphère gauche ou difficultés à tenir debout lorsque c'est l'hémisphère droit qui est atteint. Nous avons fait l'hypothèse que l'hémisphère droit serait associé à une intégration des informations proprioceptives plus pertinente dans le but de contrôler notre posture bipodale. Nous avons donc perturbé ces informations par l'utilisation de vibrations tendineuses et observé les réactions posturales induites pour différents groupes (sujets jeunes, âgés et patients hémiparétiques). Nos résultats démontrent l'utilisation préférentielle de ces informations sensorielles par l'hémisphère droit, dans la gestion et l'organisation posturale au niveau spatial et multi-segmentaire. L'utilisation de ces stimulations proprioceptives pourrait être un facteur important dans la prise en charge thérapeutique de certaines populations pathologiques. / A cortical injury leads to some distinct trouble depending on the injured side; speech and language troubles when the left brain is damaged or standing difficulties when the right brain is injured. Our hypothesis was that the right brain hemisphere permitted a more pertinent integration of proprioceptive information to control the upright position. We perturbed the proprioceptive information with tendon vibration and we observed the induced postural reactions for several groups (young and senior adults, stroke patients). Our results show that proprioceptive information is better processed by the right hemisphere, reflected by control and postural organization at spatial and multi-segmental levels. Proprioceptive stimulations may be an important tool for the rehabilitation of several pathological populations.