Due to the common belief that language is unique to humans, great emphasis has been placed on the neocortex, while the role of the subcortical areas has been minimized. This project used event-related functional magnetic resonance imaging (fMRI) to study the linguistic involvement of the basal ganglia (BG). Previous research has demonstrated that the BG are implicated in building up sequences of behavior into meaningful, goal-directed repertoires This study developed the idea of motor sequencing into linguistic sequencing to test the BG's involvement in the abstract sequencing of language. Since past imaging studies failed to present a coherent picture of the BG laterality, which might be due to the absence of the control for subjects' familial handedness background, this subject factor was also investigated.Twenty-four right-handed, neurologically healthy English speakers were recruited. Half of them had left-handed blood relatives (FS+); the other half did not (FS-). Their tasks included 1) linguistic sequencing--reordering phrases into a sentence or reordering words along the general-specific dimension, 2) non-linguistic sequencing--swapping designated phrases/words and 3) repeat--repeating words in their original sequence. Voxel-wise analysis showed that both the BG and cortical areas were activated when subjects performed a reordering task. Region of interest (ROI) analysis demonstrated that the BG were involved in linguistic sequencing (reorder - repeat) and that Broca's area and the caudate head were co-opted in computing hierarchical structure (reorder - swap). Although familial sinistrality did not alter the activation pattern of Broca's area and the caudate head, it played a role in their activation asymmetry: both subject groups had left-lateralization in the inferior frontal gyrus, but they failed to show identical laterality in the BG. A possible explanation based on the direct and indirect pathways in the BG was offered and the laterality discrepancy was attributed to these two groups' different time course of language acquisition.To summarize, this study suggested that the BG, especially the head of the caudate nucleus, were involved in the abstract sequencing of language and that the distinct brain asymmetry associated with different familial sinistrality background might be rooted in the BG.

Le bien-être animal est considéré un phénomène multidimensionnel basé sur les conditions et les expériences de vie de chaque individu, et lié aux fonctions organiques et à la sensibilité de l’individu même. L’étude des émotions animales est complexe mais les hypothèses sur leurs états émotifs peuvent être formulées sur la base de mesures neurophysiologiques, comportementales et cognitives. Des études récentes ont montré que la latéralité cérébrale et comportementale, la fréquence cardiaque et l'activité cérébrale (mesurée par électroencéphalographie sont des paramètres qui permettent d’évaluer la perception de la valence et du niveau stimulant des émotions chez l’animal et l'Homme. Le but principal de ce projet de thèse était d’étudier la perception que les chiens et les chevaux ont du contenu émotionnel des signaux humains et l’impact potentiel que peuvent avoir ces signaux sur l’état émotionnel de ces animaux et par conséquent sur leur bien-être. Dans ce but, nous avons présenté à ces animaux des stimuli exprimant diverses émotions. Nous avons utilisé une approche intégrée combinant l’analyse de la latéralité comportementale, de la fréquence cardiaque, de l’activité cérébrale et du comportement des sujets afin de répondre à 2 questions: 1) les chiens et les chevaux perçoivent-ils le contenu émotionnel des signaux humains? 2) Les chiens et les chevaux attribuent-ils une valence et une intensité différentes selon les émotions humaines perçues. Les résultats de ce travail de thèse montrent que les chiens et les chevaux traitent différemment les signaux émotionnels en fonction de leur valence et de leur intensité. La perception de la voix de l'homme par le cheval est modulée par la valence des interactions homme-cheval antérieures et par les conditions de vie des chevaux. En ce qui concerne les chiens, nos résultats montrent qu’ils discriminent et perçoivent les émotions contenues dans les signaux visuels, auditifs et olfactifs humains différemment, et nous fournissent de nouvelles connaissances sur le fonctionnement émotionnel du cerveau du chien. Les résultats de ce travail de thèse apportent un cadre théorique pour définir des paramètres utiles à l'évaluation du bien-être animal. / Animal welfare is considered to be a multidimensional phenomenon based upon life experiences and conditions, characterized by how an individual feels and functions. The study of emotions in animals is difficult but assumptions of emotional states are usually derived from neurophysiological, behavioral and cognitive measurements. Recent literature shows that cerebral and behavioral laterality, cardiac activity and brain activity (measured by electroencephalography) are suitable parameters to examine animals’ and human emotional processing along the valence and arousal dimensions. The main aim of the present research project was to investigate dogs and horses perception of the emotional content of human signals that potentially affects animals’ affective state and welfare. An integrated approach combining the analysis of behavioral lateralization, cardiac and brain activity, and subjects’ behavior was applied in order to answer to the following questions: 1) Do dogs and horses perceive the different emotional content of human signals? 2) Do dogs and horses attribute a different valence and intensity to the human emotions perceived? Overall, the results of this thesis project demonstrate that dogs and horses process differently emotional signals according to their valence and intensity. In particular, horses perception of a human voice is modulated by the valence of the prior horse-human interactions and by subjects’ living conditions. As for dogs, results demonstrate that they discriminate and perceive differently the emotional content of human visual, auditory and olfactory signals, providing new insights into the emotional functioning of the canine brain. The current research offers a theoretical framework for defining useful parameters to evaluate animal welfare.

Thesis (M.A.(Research Psychology)) --University of Limpopo, 2016. / Refer to document

Early visual processing in the avian brain has been studied extensively, the retina and midbrain in particular. However, a clear understanding of the higher visual centers in the forebrain (the telencephalon and thalamus) remains poor. Two structures located within the avian visual telencephalon, the entopallium (E) and the lateral portion of the intermediate nidopallium (NIL), merit extensive investigation based on their critical role in visual processing. The goal of the current study was to further clarify the anatomical characteristics of E and NIL. Visual information that reaches these telencephalic structures is mostly from the contralateral retina. Thus, blocking visual input on one side affects the opposite hemisphere, but leaves the hemisphere on the same side largely unaffected. This unique property of the avian visual system was used in order to emphasize neurochemical expression in the higher visual structures. After blocking visual input to one hemisphere either by monocular occlusion or unilateral lesion of the nucleus rotundus we examined the expression of specific neuroanatomical markers; namely cytochrome oxidase (CO) and the calcium binding protein, parvalbumin (PV) in E and ZENK protein expression in NIL. . Our results showed there were significantly more PV-ir cell bodies in the inner region of E compared to the outer region. In terms of PV-ir neuropil, regional differences within E were significant. In particular, the ventrolateral E tended to have a higher density of PV-ir neuropil than other regions except the most ventromedial area which was also high in PV-ir. Differential CO staining patterns were observed as well. However, unlike PV-ir neuropil the ventro-intermedial area showed a low level of CO staining compared to the other areas. Finally, there was a significant reduction of ZENK-ir cell bodies on NIL in the experimental hemisphere compared to control side. Based on this differential expression of ZENK, it was possible for the first time to visualize the location of NIL. The findings presented here are discussed in terms of their relevance to the identification of the size and extent of NIL and the heterogeneous nature of E.

This study investigated the associations between (1) handedness (demonstrated preference of one hand for the performance of most unimanual tasks) and neuroanatomical asymmetry (measurable differences in width between the cerebral hemispheres) and (2) familial history of handedness (the presence of a left-handed sibling or parent of a right-handed subject) as an intervening factor in the relation between handedness and neuroanatomical asymmetry. Width measurements of the brain were derived from computerized tomographic ( CT) films and grouped in to categories by hand preference (measured by the Edinburgh Handedness Inventory) and family history. The measurements of right (n=68), right with left-· handed relatives (n=24), and left-handed (n=16) groups were then compared by width and other transformations of the brain measurements. Subjects were adults of both sexes who had been referred for neurologic examination and were diagnosed as free of major distorting brain pathology. Hemispheric widths were compared by group, as ratios (left÷right) and as differences (left-right). Analysis of variance revealed significant differences between right-hemisphere widths at three percentages of brain length in the posterior occipital and temporal-parietal portion of the right hemisphere. The two right-handed groups had significantly smaller right-hemisphere measurements than the left group at 80% (p=.03), 75% (p= .012), and 60% (p= .029) of brain length. There were no significant left-hemisphere differences between the groups. In terms of ratios of sides and differences between sides in the same brain region, the left - handed group was different from the right-handed group at the p Handedness appears to be moderately associated with neuroanatomical asymmetry. The differences in sizes of brain structures and their relation to functionally lateralized abilities may shed light on the processes by which each hemisphere becomes specialized to perform specific tasks and other aspects of individual differences.

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.

The domestic chick (Gallus gallus domesticus) has been widely used as an animal model to investigate spatial orientation and the neural mechanisms underlying this function. In all vertebrate species the hippocampus plays an essential role in spatial orientation. Since the hippocampus is a bilateral structure, it is important to investigate the specific role of the left and the right hippocampi in spatial processing. Although, the domestic chick has been often used as animal model to assess cognitive lateralization, the involvement of the left and the right hippocampal formation in spatial orientation has been poorly investigated in this model. Behavioral studies using monocular eye occlusion have shown that in chicks the left eye-system (right hemisphere) is involved in the elaboration of spatial relational information, while the right eye-system (left hemisphere) processes local information. However, while visual lateralization in chicks had been traditionally considered to be induced by embryonic light exposure, recent studies suggest the presence of structural and behavioural asymmetries also in dark-incubated chicks. Thus, the main aim of this thesis was to test the lateralization of hippocampal functions in dark incubated chicks, both in spatial and non-spatial tasks. In the first study dark-incubated chicks were trained to orient in a large circular arena using spatial relational information provided by free-standing objects. Once chicks reached a learning criterion they were tested binocularly or under a monocular eye-occlusion condition. This study provided the first demonstration that domestic chicks are able to orient by relational spatial information provided by free-standing objects, in binocular vision conditions. However, if either one of the two eyes was occluded, chicks failed the orientation task. These results show that at least in dark-incubated chicks binocular integration is needed to solve this spatial orientation task. We also investigated if chicks have a preference to orient by local or spatial information provided by free-standing objects and if this ability is influenced by eye occlusion. Chicks preferred to use local over spatial cues to orient, both in binocular and monocular conditions (independently of which eye was occluded). These results indicate that local cues are processed by both eye-systems and do not require access to information from both eyes, contrary to relational spatial cues. Using the same setup, in the second study we directly investigated the involvement of chicks’ left and right hippocampal formation during orientation by free-standing objects. For this purpose we performed an immunohistochemical staining of the immediate early gene product c-Fos (a neural activity marker). Two independent groups of dark-incubated chicks were trained to find food in the large circular arena and the level of hippocampal activation was compared between the two groups. One group was trained to orient exclusively by local cues, while the other was orienting by spatial relational information provided by free-standing objects. This revealed selective activation of the right hippocampus during orientation by spatial relational information in dark-incubated chicks. While monocular occlusion has often been used to test lateralization of spatial functions in chicks, it is still unclear whether this manipulation affects hippocampal activation. The aim of the third study was to clarify this issue, by exposing dark-incubated chicks to a novel environment in conditions of monocular occlusion or binocular vision. Activation of the hippocampal formation was once again measured by c-Fos expression. Exposure to a novel environment is known to trigger hippocampal activation in different animals, including domestic chicks. As expected, exposure to the novel environment activated the hippocampus in binocular vision conditions. However, if either one of the eyes was occluded, the hippocampal c-Fos expression did not rise above what observed in the baseline condition (chicks maintained in a familiar environment). Thus, successful hippocampal response to a novel environment requires input from both eyes. Our results also suggest that monocular occlusion equally affects the left and the right hippocampus. Overall, access to information from both eyes plays a crucial role for the acquisition of a spatial map of a novel environment, in line with the behavioral results of the first study. Moreover, a task independent lateralization effect, with higher c-Fos expression in the left compared to the right hippocampus, could be observed in all the experimental conditions. This confirms the presence of neuroanatomical lateralization in dark-incubated chicks. The last study investigated whether chicks’ hippocampus would also respond to novel social stimuli, in line with the activation observed in this structure after exposure to a novel environment. Only few studies have directly investigated the involvement of birds’ hippocampal formation in social functions. Here, the hippocampal activation was compared between chicks exposed to an unfamiliar conspecific vs. chicks exposed to a familiar one. We found that the ventral and dorsomedial portion of the right hippocampus of dark-incubated chicks responds to an unfamiliar individual. This provides the first demonstration of hippocampal sensitivity to social novelty in birds. Overall the studies performed in this thesis indicate a selective lateralized involvement of domestic chicks’ hippocampal formation not only in spatial, but also in social functions.

No description available.

An object in the visual field can be perceived as a whole and as the parts from which the whole is composed. Early investigations into whole-part processing led to the hypothesis that the global aspect, the whole, is processed before the local aspects, the parts. However, recent electrophysiological work shows that in the early stages of processing, the global and local levels of an object are processed in parallel. In addition, a processing asymmetry exists in that the right hemisphere is biased for global level processing whereas the left hemisphere is biased for local level processing. In an ERP study, I examined the lateralization and time-course of global-local processing in normal adult humans and found further evidence for lateralized, parallel processing of global-local stimuli. More importantly, I found that task demands affected the latencies at which lateralized differences between the two levels emerged: a condition in which interference from one level on the other was minimal showed very early, lateralized attentional effects (80 ms). In a relatively more demanding condition, lateralization of global and local processing was not evident until 200-350 ms. One possible explanation is that as the influence of distractors at the unattended level increases, resources in both hemispheres are engaged. To corroborate these findings, I included conditions in which subjects were required to switch attention among levels and visual fields: Evidence for lateralization and parallel processing persisted. Moreover, the additional load placed on the system by the switching conditions was apparent at the N1 component and support for right hemisphere attention switching mechanisms was obtained. / Thesis / Master of Science (MSc)

Sixty right-handed men, half classified as anxious without depressive symptoms, the other half as nonanxious, participated in a tachistoscopic study of the influence of anxiety without depression on hemispheric processing of Ekman and Friesen's (1976) happy, angry, and neutral emotional faces. Results were counter to hypotheses, where anxious subjects' reaction times to affective valences were slower than nonanxious subjects. Additionally, anxious subjects failed to demonstrate a negative affective bias for neutral stimuli. Results are discussed in terms of arousal theory, where anxious subjects may be considered overaroused for the tachistoscopic task, thereby exhibiting slower reaction times to affective stimuli. More specific neuropsychological hypotheses for anxious individuals without depression versus nonanxious individuals in terms of concurrent anterior dysfunction and posterior hyperarousal are discussed. / Master of Science