DHA depletion in brain was associated with impairment on spatial learning and memory in rat. The Morris water maze test found that the n-3 deficient rats spent more time and swam a longer distance to find the hidden platform compared with the n-3 adequate group, indicating that n-3 Def rats had a poorer spatial learning ability and memory. The results suggest that learning and memory are partially related to the brain DHA status in rat. / Docosahexaenoic acid (DHA, 22-6n-3) and arachidonic acid (AA, 22:4n-6) are long-chain polyunsaturated fatty acids (LCPUFA), which are important for the structural development of mammalian central nervous system and are accumulated in large amounts in the developing brain, retina and sperm. Deficiency in DHA and AA syndromes can occur if these fatty acids and their precursors (linoleic and linolenic acid) are insufficient in diet. It had been reported that DHA deficiency in animal brain led to a poor performance in learning ability and other abnormal behavior in rodents. In addition, DHA and AA are the unique fatty acids in human milk. Many studies reported that children who were breast-fed got higher intelligent scores than those who were formula-fed. Thus, a large number of studies suggested that DHA and AA should be added into infant formula to mimic the composition of human milk. / In summary, DHA distribution, depletion and recovery were region-specific in rat brain. DHA deficiency could lead to impairment on spatial learning in rat. The underlying mechanism of learning deficit might not be attributed to changes in antioxidant enzymes in rat brain. Although impairment on spatial learning was observed in DHA-deficient rat, a meta-analysis of published data demonstrated that DHA and AA supplement in infant formula had no effect on cognitive development in children. / No significant relationship between DHA level and brain antioxidant enzyme activities was observed, including catalase (CAT), Cu-Zn superocide dismutase (Cu-Zn SOD), Mn superocide dismutase (Mn SOD) and glutathione peroxidase (GPx). These enzyme activities varied with regions of brain. A lower activity of CAT, Mn SOD and GPx in hippocampus and cortex would make them particularly susceptible to oxidation damage compared with other regions. The present results did not support the view that the spatial learning and memory impairment in DHA depletion was associated with antioxidant status in brain. / The meta-analysis indicated that breast-feeding was positively associated with a higher cognitive development than formula-feeding. However, no benefit was found for infants who received formula supplemented with DHA alone or DHA plus AA compared with those fed traditional formula based on available data. The results suggest that the beneficial effect of breast-feeding over formula-feeding can not be solely attributed to DHA and AA present in breast milk. / The objectives of present study were to (1) examine the distribution, depletion and recovery of DHA in rat brain; (2) investigate the effect DHA deficiency in rat brain on spatial learning behavior; (3) study the effect of DHA deficiency on antioxidant enzymes in rat brain; and (4) analyze whether DHA and AA supplementation has any beneficial effect on cognitive development and quantify their effect size in children by conducting a meta-analysis of the published data, and adult rats, the region with the highest DHA percentage was cortex, whereas in aged rats, both cortex and cerebellum were the regions with the highest DHA percentage. DHA concentration in rat brain increased with age. DHA was not proportionally depleted and recovered in different regions of rat brain when the rats were maintained on an n-3 fatty acid deficient diet for two generations. The present results demonstrated that the distribution of DHA and AA was region-specific. / Xiao Ying. / "August 2006." / Adviser: Zhen Yu Chen. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1566. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 140-156). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Thesis (MA (Visual Arts))--Stellenbosch University, 2008.

Our eyes are horizontally separated in the head by approximately 6.5cm. As a result of this separation there are subtle differences in the position of corresponding image points within the two eyes. The horizontal component of this binocular positional difference is termed horizontal disparity. Horizontal disparity is an important visual cue as once scaled with an estimate of the viewing distance, it can theoretically provide full metric information about the structure of the world. This thesis will address the issue of how binocular visual cues are used by the human visual system for the estimation of three-dimensional (3-D) shape for perception and visuomotor control. The research presented is particularly focused on understanding why biases in the perception of 3-D shape from binocular cues are found, their importance for perception and visuomotor control and how these biases may be overcome by combining binocular cues with other sources of visual information.

published_or_final_version / Education / Doctoral / Doctor of Philosophy

This study attempted to clarify the relationship between visuo-spatial abilities and reading achievement at the first and fifth grades. Groups of good and poor readers were selected at each grade level on the basis of student's scores on the Wide Range Achievement Test in Reading. All subjects had obtained an I.Q. score of ninety or better. The sample was composed of twenty-one females and twenty-seven males. Four tests from the Reitan-Indiana Neuropsychological Battery were given to assess visuo-spatial ability. It was hypothesized that visuo-spatial abilities are related positively to reading achievement and that this relationship is approximately equal at the two grade levels. Statistical analyses of results gave partial support to the first hypothesis.

This research was designed to investigate the fundamental nature in which blind people utilize audible cues to attend to their surroundings. Knowledge on how blind people respond to external spatial stimuli is expected to assist in development of better tools for helping people with visual disabilities navigate their environment. There was also interest in determining how blind people compare to sighted people in auditory localization tasks. The ability of sighted individuals, blindfolded individuals, and blind individuals in localizing spatial auditory targets was assessed. An acoustic display board allowed the researcher to provide multiple sound presentations to the subjects. The subjects’ responses in localization tasks were measured using a combination of kinematic head tracking and eye tracking hardware. Data was collected and analyzed to determine the ability of the groups in localizing spatial auditory targets. Significant differences were found among the three groups in spatial localization error and temporal patterns.

Os parques são espaços de lazer essenciais para convivência e interação na sociedade, sendo locais públicos, que devem oferecer igualdade de possibilidades e utilização por todos, não segregando ou excluindo. Mas, na realidade, os parques públicos urbanos brasileiros ainda não dispõem de condições básicas para o deslocamento seguro e autônomo das pessoas com deficiência visual. Por meio desta pesquisa, objetivou-se identificar as restrições que o ambiente impõe a esse grupo de indivíduos, bem como conhecer suas necessidades, habilidades e limitações, compreendendo a sua percepção do espaço, e identificando a influência dos elementos cognitivos auxiliares dessa percepção. Buscou-se ainda avaliar a eficácia das medidas de acessibilidade implantadas em parques urbanos para as pessoas com deficiência visual, analisando a sua relação com estes espaços livres públicos de lazer. Para tal, realizou-se uma revisão bibliográfica aprofundada acerca do tema, atentando para as normas e legislações vigentes; entrevistas com especialistas de outras áreas do conhecimento, como psicólogos, educadores e especialistas em orientação e mobilidade; e contou-se com a contribuição de pessoas com deficiência visual por meio da aplicação de ferramentas como entrevistas, grupos focais, observações participantes, e passeios acompanhados em alguns parques de São Paulo, para a coleta de dados. O estudo pautou-se por uma abordagem qualitativa de pesquisa, cujos resultados ressaltaram a importância dos parques como espaços de lazer para as pessoas com deficiência visual e a atual falta de acessibilidade dos mesmos. Apesar da legislação brasileira, e em especial da cidade de São Paulo, estabelecer a garantia de acesso e utilização dos parques pelas pessoas com deficiência em geral, essa determinação não é cumprida pelo próprio poder público, responsável pelo gerenciamento e manutenção dos parques uranos. E em relação às normas atuais, esta dissertação sugere alguns acréscimos e recomendações para que os parques realmente possibilitem o deslocamento autônomo e independente das pessoas cegas e com baixa visão. Por fim, com a realização desta pesquisa percebe-se que os ambientes muito abertos, amplos e com muitas pessoas são naturalmente complicados para as pessoas com deficiência visual, mas é possível deixá-los totalmente acessíveis para este público-alvo, e é algo necessário, visto que esta parte da população demonstrou grande interesse e deve ser incluída plenamente nos espaços públicos em questão. / Parks are places for leisure activities, they are essential for society\'s coexistence and interaction, being by definition public sites that should offer equal possibilities and universal use, never segregating or excluding. However, in fact, urban public parks in Brazil still do not dispose of basic requirements for the safe and independent displacement of the visually impaired persons. The present research seeks to identify the restrictions imposed by the environment to this group of individuals, as well as knowing their needs, abilities and limitations, understanding their perception of space and identifying the influence of the cognitive elements that assist this perception. Additionally, the present work intends to evaluate the effectiveness of the accessibility measures implemented in urban parks for the visually impaired individuals, analyzing their relationship with those public free leisure sites. In order to do so, a deep bibliographic review about the theme was done, with special attention to the current rules and legislations; interviews with specialists from other fields of knowledge such as psychologists, teachers and specialist in orientation and mobility. The research has been aided by visually impaired persons whom have participated in several activities for data collection, interviews, focus groups, participant observations, as well as accompanied tours through some parks of Sao Paulo. This study is guided by a qualitative approach research method, which results highlighted the importance of parks as leisure sites for visually impaired individuals and the actual lack of accessibility of those free public sites. Even though the Brazilian legislation and specially the Sao Paulo municipality laws do establish that access and use of the parks by the visually impaired citizens is guaranteed, the public forces do not comply with such determinations, though those forces answer for the management and maintenance of urban parks. In relation to the current laws, this dissertation suggests some additions and recommendations so that parks really enable the independent and self-governing displacement of the blind and of the low vision persons. Conclusively, the present research allow us to perceive that environments that are very open, wide and crowded are naturally challenging for the visually impaired, but it is possible to make those environments completely accessible to this audience, and it is rather necessary, once part of this population showed great interest and should be fully included in the public sites concerned.

The hippocampal-medial prefrontal circuit has been shown to serve a critical role in decision making and goal directed actions. While the hippocampus (HF) exerts a direct influence on the medial prefrontal cortex (mPFC), there are no direct return projections from the mPFC to the HF. The nucleus reuniens (RE) of the midline thalamus is strongly reciprocally connected with the HF and mPFC and represents the major link between these structures. We investigated the role of RE in functions associated with the hippocampus and the mPFC -- or their interactions. Using two different inactivation techniques (pharmacological and chemogenetic), we sought to further define the role of RE in spatial working memory (SWM) and behavioral flexibility using a modified delayed non-match to sample (DNMS) working memory task. We found that the reversible inactivation of RE with muscimol critically impaired SWM performance, abolished well-established spatial strategies and produced a profound inability to correct non-rewarded, incorrect choices on the T-maze (perseverative responding). We observed similar impairments in SWM following the chemogenetic (DREADDs) inactivation of RE or selective RE projections to the ventral HF. In addition, we showed that the inhibition of RE terminals to the dorsal or ventral HF altered task related behaviors by increasing or decreasing the time to initiate the task or reach the reward, respectively. Finally, we examined discharge properties of RE cells across sleep-wake states in behaving rats. We found that the majority of RE cells discharge at high rates of activity in waking and REM and at significantly reduced rates in SWS, with a subpopulation firing rhythmically in bursts during SWS. We identified five distinct subtypes of RE cells that discharged differently across vigilant states; those firing at highest rates in waking (W1, W2), in REM sleep (R1, R2) and SWS (S1). Given the differential patterns of activity of these cells, we proposed they may serve distinct functions in waking – and possibly in SWS/REM sleep. In sum, our findings indicate that RE is critically involved in mnemonic and executive functions and the heterogeneous activity of these cells support a role for RE in arousal/attention, spatial working memory and cognition. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Male C7BL/6J mice were implanted with bilateral dorsal CA1 guide cannulae. After confirming that intrahippocampal microinfusion of muscimol impaired hippocampal function, demonstrated by impaired performance in the Morris water maze, the influence of intrahippocampal muscimol was tested in the Novel Object Recognition paradigm. During a test session 24 h after the last habituation/sample session, mice were presented with one familiar object and one novel object. Successful retention of object memory was inferred if mice spent more time exploring the novel object than the familiar object. Results demonstrate that muscimol infused into dorsal CA1 region prior to the test session eliminates novel object preference, indicating that the hippocampus is necessary for the retrieval of this non-spatial memory - a topic that has garnered much debate. Understanding the similarities between rodent and human hippocampal function could enable future animal studies to effectively answer questions about diseases and disorders affecting human learning and memory. / by Lisa Rios. / Thesis (M.A.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

The endogenous, or voluntary, control of visuospatial attention relies upon interactions within a frontoparietal dorsal attention network (DAN) and this network’s top-down influence on visual occipital cortex (VOC). While these interactions have been shown to occur during attention tasks, they are also known to occur to some extent at rest, but the degree to which task-related interactions reflect either modulation or reorganization of such ongoing intrinsic interactions is poorly understood. In addition, it is known that in spatial neglect—a syndrome following unilateral brain lesions in which patients fail to attend to the contralesional side of space—symptom severity covaries with disruptions to intrinsic interhemispheric interactions between left and right homologous regions of the DAN; however, similar covariance with disruptions to intrahemispheric interactions within the DAN, and between the DAN and VOC, has not been demonstrated. These issues are addressed herein via the measurement of both undirected and directed functional connectivity (UFC, DFC) within the DAN and between the DAN and VOC. UFC and DFC were derived from correlations of, and multivariate vector autoregressive modeling of, fMRI BOLD time-series, respectively. Time-series were recorded from individuals performing an anticipatory visuospatial attention task and individuals at rest, as well as from stroke patients either with or without neglect and age-matched healthy controls. With regard to the first issue, the results show that relative to rest, top-down DAN-to-VOC influence and within-DAN coupling are elevated during task performance, but also that intrinsic connectivity patterns are largely preserved during the task. With regard to the second issue, results show that interhemispheric imbalances of intrahemispheric UFC and DFC both within the DAN and between the DAN and VOC strongly correlate with neglect severity, and may co-occur with functional decoupling of the hemispheres. This work thus demonstrates that the intrinsic functional integrity of the DAN and its relationship to VOC is crucial for the endogenous control of visuospatial attention during tasks, and that the compromise of this integrity due to stroke likely plays a role in producing spatial neglect. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection