Visual perception theory distinguishes between two distinct levels of object processing: holistic, based on global shape, and configural, based on local features and/or component parts. Empirical evidence suggests that different cortical regions may support these levels; holistic processing correlates with activation in the lateral occipital-temporal cortex (LOC), whereas configural processes correspond to activation in the parietal lobe, particularly the intraparietal sulcus (IPS). This study combined theories of visual part structure with neuroimaging methods to investigate the relative contribution of holistic and configural processing in an ecologically valid object recognition task. Rather than rely on stimuli specifically designed to evoke holistic or configural processing, this study used photographs of objects selected without a priori assumptions concerning physical part structure. Twenty participants viewed objects at fixation while undergoing fMRI, followed by a behavioral object identification task involving the same objects presented in peripheral vision. Behavioral data were analyzed according to theories of visual crowding to yield an objective estimate of the number of parts perceived within each object. Neuroimaging results revealed increased activation for holistic objects containing fewer parts in the right parietal lobe and superior temporal gyrus and bilaterally in the fusiform gyrus, suggesting a relation between holistic processing areas and object perception. Configural objects with many parts elicited increased activation in the left angular gyrus. This study, to our knowledge, is the first to investigate the cortical visual regions involved when observers engage in holistic and configural processing as a natural part of visual recognition. / Master of Science

The current research project consists of three experiments on motor asymmetry tasks. Electroencephalogram (EEG) was applied to examine neural activation patterns in coincidence with motor performance across ages. A total of 48 right-handed participants were recruited and conducted the Purdue Pegboard test, graphic test, and aiming test. The three motor tasks were designed to assess functional asymmetry at behavioral level. Brain activities were acquired through EEG while performing the tasks. Measures of EEG signals were mean relative power of 12 electrodes. To examine movement-related brain activity, Mu rhythm within a frequency band of 8 Hz to 12 Hz was filtered with a high-pass of 1 Hz and a low-pass of 50 Hz. Statistical analyses aimed to examine effects of aging on motor asymmetry and hemispheric asymmetry. One-way repeated ANOVA was first conducted on each age group separately to identify motor asymmetry characterized by a significant difference between left hand and right hand. In addition, two-way (Age × Hand) mixed design ANOVA was implemented to examine whether age-related changes in motor asymmetry were significant. The three motor tasks indicated significant motor asymmetry in young adults, with the dominant (right) hand having an advantage over the nondominant (left) hand. However, no significant results were identified in the manual performance of older adults, suggesting reduction of motor asymmetry in aging population. In addition, the two-way ANOVA identified a significant interaction effect between age and hand, which further confirmed the significant changes in motor asymmetry over the life span. Hemispheric activation indicated consistent pattern of changes with motor performance. Hemispheric activation of young adults was strongly lateralized during motor performance, with the frontal regions in the contralateral hemisphere being more activated than the corresponding regions in the ipsilateral hemisphere. On the other hand, hemispheric activation of older adults indicated increased ipsilateral activation which resulted in bilateral and symmetric patterns. The current research substantiated hypothesis proposed in previous motor behavior research that reduced motor asymmetry linked with less hemispheric lateralization in older adults. Based on evidence from motor behavior and neural connectivity, we concluded that aging reduces asymmetries at both behavioral and neural levels.

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An important field of interpreting research, neurolinguistic approach emerged soon after the shift towards an interdisciplinary approach to research into interpreting. The mutually beneficial collaboration between neurolinguists and interpreters has been centred mainly on the issue of language representation in interpreters as bilingual subjects, namely on the role each of the two cerebral hemispheres plays depending on the task (automatic speech production, shadowing, translation of single words or phrases, simultaneous interpreting), choice of interpreting strategy (literal vs. meaning-based interpretation) or on the direction of interpreting (B to A vs. A to B language). The thesis focuses on the research into hemispheric lateralization done at SSLMIT, University of Trieste, Italy - the place where, in the 80s, the neurolinguistic approach was first adopted. The Trieste School then remained its centre for approximately ten years. The beginning chapters of this theoretical study present the fundamentals of neuranatomy, neurophysiology and neurolinguistics, necessary for understanding of the mental processes underlying simultaneous interpretation. Furthermore, relevant neuroimaging methods are introduced that either have already been used in or could be applied to interpreting research in the...

The purpose of this thesis focused on a literature curriculum designed to improve reading comprehension through the stimulation of the right hemisphere of the brain. A case study of this curriculum development effort involved a third-grade student from a local public 2 school. He was a part-time Specific Learning Disability student with weaknesses in visual organization, visual concentration, and reading comprehension. A time span of six weeks was dedicated to increasing the child's reading comprehension within a literature framework through the use of right-brain stimulants, specifically, color and visualization. The Gates-MacGinitie Reading Test, Level C, administered at the conclusion of the instructional sessions, and teacher observation provided the evaluation of the curriculum. Results of the study proved inconclusive. Further field study was recommended.

A large body of research has depicted relative arousal of the left and right cerebral hemispheres as related to utilization of particular defensive coping styles, level of anxiety, and perceptual styles. The right and left hemispheres are also presented in the literature as differing in visual-spatial and verbal-auditory short term memory abilities. The present research studied 127 right handed undergraduates' relative performance on forward spatial and digits memory spans in relation to hemispheric lateralization and other perceptual and personality variables hypothesized in the literature to be related to hemispheric arousal. It was hypothesized that the forward spatial and digit memory spans would display asymmetrical sensitivity to hemispheric arousal. That is, in a series of successive factor analyses, a hemispheric balance factor, a trait anxiety factor, and a short term memory factor would emerge. The three factors were hypothesized to be unrelated to each other. During an initial group pretesting, subjects were given pencil and paper measures of handedness, trait anxiety, and several defensive coping styles. During a second individual testing, subjects were administered measures of short term memory, field independence, and a computerized presentation of geometric designs which measured the subjects ability to detect differences which occurred at either the global or analytic level (Navon task). The factor analyses revealed only the hypothesized trait anxiety factor. The hypothesized short term memory and hemispheric balance of arousal factors did not emerge. Instead, a. defensive coping style factor and separate verbal—auditory and visual-spatial short term memory factors emerged. Several methodological difficulties of the present study which possibly contributed to the failure of the two hypothesized factors to emerge were discussed. Several additional findings, including sex differences in hemispheric lateralization, were presented. Also, signal detection analysis revealed a pattern such that trait anxious subjects were biased toward over-reporting differences on the Navon task. Implications for further research were presented.

Il apparaît, suite aux résultats de plusieurs études comportementales et d’imagerie cérébrale, que les hormones gonadiques peuvent moduler le fonctionnement cérébral chez la femme. Les asymétries cérébrales fonctionnelles (ACFs), en particulier, changeraient en fonction du niveau de progestérone et d’œstrogène. On a également observé que lorsque le taux d’œstrogène est bas, les performances aux tâches impliquant l’hémisphère droit sont améliorées. Par contre, les preuves de l’action physiologique de ces deux hormones sur le cerveau ne sont pas très nombreuses. Le peu d’études d’électrophysiologie cognitive qui ont porté sur les effets du cycle menstruel ont rapporté que la composante P300 y serait sensible. Aucune n’a cependant utilisé une tâche d’habileté spatiale ou de rotation mentale qui sont connues pour impliquer davantage l’hémisphère droit. Le but de la présente étude est de documenter les changements électrocorticaux reliés aux variations hormonales lors d’une tâche de rotation mentale. Notre hypothèse de départ est que le taux d’œstrogène influencera l’activité électrocorticale et la latéralisation. Les potentiels évoqués cognitifs ont été comparés chez les mêmes femmes (n=12) lors d’une tâche de rotation mentale, répétée à deux périodes du cycle menstruel. Nos résultats démontrent que la condition de rotation induit une latéralisation de l’activité pariétale, vers l’hémisphère gauche, quand le niveau d’œstrogène est bas. Par contre, lorsque le niveau d’œstrogène est élevé, il n’y a aucune latéralisation. Par ailleurs, nous avons observé une augmentation de l’amplitude de la P300 lors du niveau oestrogénique élevé. En conclusion, les fluctuations oestrogéniques du cycle menstruel ont un impact sur la latéralisation de l’activité électrocorticale, lors d’un effort de rotation mentale. / After many behavioral and some neuroimaging studies, it appears that the gonadic hormones can modulate the neuronal function of women's brain. In particular, the functional cerebral asymmetries can be affected by the level of progesterone and estrogens. It has been observed that when the level of estrogen is low, the performance at task that engages more the right hemisphere is enhanced. However, there is a lack of evidence for the physiological actions of these two hormones on the brain. The few event-related potential studies taking into account the menstrual cycle effects, had noticed that the component P300 can be affected. No electrophysiological study has used a mental rotation task or spatial ability tests which are known for their right hemisphere dominance. The aim of the present research is to document the effect of hormonal variations on the electrocortical activity, using a mental rotation task. Our hypothesis is that estrogen levels affect electrocortical activity and lateralization. The ERPs were compared in the same women (n = 12) during a mental rotation task, repeated over two periods of the menstrual cycle. Our results show a lateralization of the left parietal activity when estrogen levels are low and during the rotation. Whereas when the estrogen level is high, there is no lateralization. In addition, we observed an increase in the amplitude of P300 for this same high level. In conclusion, estrogens fluctuations associated with the menstrual cycle have an impact on the lateralization of electrocortical activity, when a mental rotation is needed.

Despite considerable research, the effects of common types of noise on verbal and spatial information processing are still relatively unknown. Three experiments, using convenience sampling were conducted to investigate the effect of auditory interference on the cognitive performance of 24 adult men and women during the Stroop test, perception of object recognition and spatial location tasks, and the perception of object size, shape, and spatial location tasks. The data were analyzed using univariate analysis of variance and 1-way multivariate analysis of variance. The Experiment 1 findings indicated reaction time performance for gender and age group was affected by auditory interference between experimental conditions, and recognition accuracy was affected only by experimental condition. The Experiment 2a results showed reaction time performance for recognizing object features was affected by auditory interference between age groups, and recognition accuracy by experimental condition. The Experiment 2b results demonstrated reaction time performance for detecting the spatial location of objects was affected by auditory interference between age groups. In addition, reaction time was affected by the type of interference and spatial location. Further, recognition accuracy was affected by interference condition and spatial location. The Experiment 3 findings suggested reaction time performance for assessing part-whole relationships was affected by auditory interference between age groups. Further, recognition accuracy was affected by interference condition between experimental groups. This study may create social change by affecting the design of learning and workplace environments, the neurological correlates of auditory and visual stimuli, and the pathologies of adults such as attention deficit hyperactivity disorder.

The observations made in brain-lesioned patients and the result of functional brain imaging studies converge to the hypothesis that the posterior parietal cortex (PPC) is involved in calculation and number processing. However, if numerical disorders generally result from a left parietal lesion, the results of some brain imaging studies suggest that the right PPC could also play a role in number magnitude processing. In order to clarify this question, we used transcranial magnetic stimulation to induce a virtual lesion of the left or right PPC in healthy subjects while they performed number comparison. Our results show that the integrity of the left PPC is a necessary condition for the precise discrimination required during close number comparison; whereas the comparison of far numbers can be performed by either hemisphere as suggested by the fact that this task is affected only by the simultaneous virtual lesion of both hemispheres. In order to better identify which processes underlie the numerical competence of the PPC, we then studied the possible interactions between number processing and visuo-motor functions. Indeed, a meta-analysis performed on functional imaging data revealed that number processing depends on parietal regions, but also on certain premotor areas, which are very close to those involved in the control of finger movements. In a first series of experiments, we thus observed an excitability increase in motor circuits during the enumeration of dots presented on a computer screen. Given that the counting task was performed with both hands at rest, this increase was interpreted as reflecting the mental simulation of pointing movements or sequential finger rising as counting goes on. In a second series of experiments, we showed that information related to number magnitude could interfere with the aperture of the finger grip required to grasp an object. These results suggest that the conformation of the hand to object size shares, with the representation of numbers, common processes for magnitude estimate. In conclusion, our thesis supports the hypothesis that our numerical capacities rely, at least partially, on visuo-motor functions involving the PPC; this could explain why the numerical capacities of the left hemisphere, which is dominant for motor activities, are more precise. / Les observations réalisées chez les patients cérébrolésés ainsi que le résultat des études d'imagerie cérébrale fonctionnelle convergent vers l'hypothèse selon laquelle le cortex pariétal postérieur (CPP) est impliqué dans le traitement des nombres et le calcul. Cependant, si les troubles du calcul résultent le plus souvent d'une lésion pariétale gauche, les résultats de certaines études d'imagerie fonctionnelle suggèrent que le CPP droit pourrait également jouer un rôle dans le traitement de la magnitude des nombres. Afin de clarifier cette question, nous avons utilisé la stimulation magnétique transcrânienne pour induire une lésion virtuelle du CPP gauche ou droit chez des sujets sains réalisant une tâche de comparaison de nombres. Nos résultats montrent que l'intégrité du CPP gauche est une condition nécessaire à la discrimination précise requise lors de la comparaison de nombres proches; la comparaison de nombres éloignés peut, quant à elle, être réalisée par l'un ou l'autre hémisphère comme le suggère le fait que cette tâche n'est affectée que par lésion virtuelle simultanée des deux hémisphères. Afin de mieux appréhender les processus sur lesquels s'appuient les compétences numériques du CPP, nous avons ensuite étudié les interactions possibles entre le traitement des nombres et les fonctions visuo-motrices. En effet, une méta-analyse réalisée sur des données d'imagerie fonctionelle a révélé que le traitement des nombres dépend de régions pariétales, mais également de certaines aires prémotrices, proches de celles impliquées dans le contrôle des mouvements des doigts. Dans une première série d'expériences, nous avons ainsi observé une augmentation de l'excitabilité des circuits moteurs lors du comptage de points présentés sur l'écran d'un ordinateur. Etant donné que la tâche de comptage était réalisée avec les mains au repos, cette augmentation a été interprétée comme le reflet d'une simulation mentale de mouvements de pointage ou d'extension séquentielle des doigts pendant le comptage. Dans une deuxième série d'expériences, nous avons montré que l'information relative à la magnitude des nombres pouvait interférer avec l'ouverture de la pince bidigitale requise pour saisir un objet. Ces résultats suggèrent que la conformation de la main adaptée à la taille des objets partage, avec la représentation des nombres, des processus communs d'estimation de la magnitude. En conclusion, notre travail supporte l'hypothèse selon laquelle nos capacités numériques pourraient, en partie du moins, reposer sur des fonctions visuo-motrices impliquant le CPP ; ceci pourrait expliquer pourquoi les capacités numériques de l'hémisphère gauche, dominant pour les activités motrices, sont plus précises.

The observations made in brain-lesioned patients and the result of functional brain imaging studies converge to the hypothesis that the posterior parietal cortex (PPC) is involved in calculation and number processing. However, if numerical disorders generally result from a left parietal lesion, the results of some brain imaging studies suggest that the right PPC could also play a role in number magnitude processing. In order to clarify this question, we used transcranial magnetic stimulation to induce a virtual lesion of the left or right PPC in healthy subjects while they performed number comparison. Our results show that the integrity of the left PPC is a necessary condition for the precise discrimination required during close number comparison; whereas the comparison of far numbers can be performed by either hemisphere as suggested by the fact that this task is affected only by the simultaneous virtual lesion of both hemispheres. In order to better identify which processes underlie the numerical competence of the PPC, we then studied the possible interactions between number processing and visuo-motor functions. Indeed, a meta-analysis performed on functional imaging data revealed that number processing depends on parietal regions, but also on certain premotor areas, which are very close to those involved in the control of finger movements. In a first series of experiments, we thus observed an excitability increase in motor circuits during the enumeration of dots presented on a computer screen. Given that the counting task was performed with both hands at rest, this increase was interpreted as reflecting the mental simulation of pointing movements or sequential finger rising as counting goes on. In a second series of experiments, we showed that information related to number magnitude could interfere with the aperture of the finger grip required to grasp an object. These results suggest that the conformation of the hand to object size shares, with the representation of numbers, common processes for magnitude estimate. In conclusion, our thesis supports the hypothesis that our numerical capacities rely, at least partially, on visuo-motor functions involving the PPC; this could explain why the numerical capacities of the left hemisphere, which is dominant for motor activities, are more precise. / Les observations réalisées chez les patients cérébrolésés ainsi que le résultat des études d'imagerie cérébrale fonctionnelle convergent vers l'hypothèse selon laquelle le cortex pariétal postérieur (CPP) est impliqué dans le traitement des nombres et le calcul. Cependant, si les troubles du calcul résultent le plus souvent d'une lésion pariétale gauche, les résultats de certaines études d'imagerie fonctionnelle suggèrent que le CPP droit pourrait également jouer un rôle dans le traitement de la magnitude des nombres. Afin de clarifier cette question, nous avons utilisé la stimulation magnétique transcrânienne pour induire une lésion virtuelle du CPP gauche ou droit chez des sujets sains réalisant une tâche de comparaison de nombres. Nos résultats montrent que l'intégrité du CPP gauche est une condition nécessaire à la discrimination précise requise lors de la comparaison de nombres proches; la comparaison de nombres éloignés peut, quant à elle, être réalisée par l'un ou l'autre hémisphère comme le suggère le fait que cette tâche n'est affectée que par lésion virtuelle simultanée des deux hémisphères. Afin de mieux appréhender les processus sur lesquels s'appuient les compétences numériques du CPP, nous avons ensuite étudié les interactions possibles entre le traitement des nombres et les fonctions visuo-motrices. En effet, une méta-analyse réalisée sur des données d'imagerie fonctionelle a révélé que le traitement des nombres dépend de régions pariétales, mais également de certaines aires prémotrices, proches de celles impliquées dans le contrôle des mouvements des doigts. Dans une première série d'expériences, nous avons ainsi observé une augmentation de l'excitabilité des circuits moteurs lors du comptage de points présentés sur l'écran d'un ordinateur. Etant donné que la tâche de comptage était réalisée avec les mains au repos, cette augmentation a été interprétée comme le reflet d'une simulation mentale de mouvements de pointage ou d'extension séquentielle des doigts pendant le comptage. Dans une deuxième série d'expériences, nous avons montré que l'information relative à la magnitude des nombres pouvait interférer avec l'ouverture de la pince bidigitale requise pour saisir un objet. Ces résultats suggèrent que la conformation de la main adaptée à la taille des objets partage, avec la représentation des nombres, des processus communs d'estimation de la magnitude. En conclusion, notre travail supporte l'hypothèse selon laquelle nos capacités numériques pourraient, en partie du moins, reposer sur des fonctions visuo-motrices impliquant le CPP ; ceci pourrait expliquer pourquoi les capacités numériques de l'hémisphère gauche, dominant pour les activités motrices, sont plus précises.