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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Activating Developmental Reserve Capacity Via Cognitive Training or Non-invasive Brain Stimulation: Potentials for Promoting Fronto-Parietal and Hippocampal-Striatal Network Functions in Old Age

Passow, Susanne, Thurm, Franka, Li, Shu-Chen 24 July 2017 (has links) (PDF)
Existing neurocomputational and empirical data link deficient neuromodulation of the fronto-parietal and hippocampal-striatal circuitries with aging-related increase in processing noise and declines in various cognitive functions. Specifically, the theory of aging neuronal gain control postulates that aging-related suboptimal neuromodulation may attenuate neuronal gain control, which yields computational consequences on reducing the signal-to-noise-ratio of synaptic signal transmission and hampering information processing within and between cortical networks. Intervention methods such as cognitive training and non-invasive brain stimulation, e.g., transcranial direct current stimulation (tDCS), have been considered as means to buffer cognitive functions or delay cognitive decline in old age. However, to date the reported effect sizes of immediate training gains and maintenance effects of a variety of cognitive trainings are small to moderate at best; moreover, training-related transfer effects to non-trained but closely related (i.e., near-transfer) or other (i.e., far-transfer) cognitive functions are inconsistent or lacking. Similarly, although applying different tDCS protocols to reduce aging-related cognitive impairments by inducing temporary changes in cortical excitability seem somewhat promising, evidence of effects on short- and long-term plasticity is still equivocal. In this article, we will review and critically discuss existing findings of cognitive training- and stimulation-related behavioral and neural plasticity effects in the context of cognitive aging, focusing specifically on working memory and episodic memory functions, which are subserved by the fronto-parietal and hippocampal-striatal networks, respectively. Furthermore, in line with the theory of aging neuronal gain control we will highlight that developing age-specific brain stimulation protocols and the concurrent applications of tDCS during cognitive training may potentially facilitate short- and long-term cognitive and brain plasticity in old age.
132

Activating Developmental Reserve Capacity Via Cognitive Training or Non-invasive Brain Stimulation: Potentials for Promoting Fronto-Parietal and Hippocampal-Striatal Network Functions in Old Age

Passow, Susanne, Thurm, Franka, Li, Shu-Chen 24 July 2017 (has links)
Existing neurocomputational and empirical data link deficient neuromodulation of the fronto-parietal and hippocampal-striatal circuitries with aging-related increase in processing noise and declines in various cognitive functions. Specifically, the theory of aging neuronal gain control postulates that aging-related suboptimal neuromodulation may attenuate neuronal gain control, which yields computational consequences on reducing the signal-to-noise-ratio of synaptic signal transmission and hampering information processing within and between cortical networks. Intervention methods such as cognitive training and non-invasive brain stimulation, e.g., transcranial direct current stimulation (tDCS), have been considered as means to buffer cognitive functions or delay cognitive decline in old age. However, to date the reported effect sizes of immediate training gains and maintenance effects of a variety of cognitive trainings are small to moderate at best; moreover, training-related transfer effects to non-trained but closely related (i.e., near-transfer) or other (i.e., far-transfer) cognitive functions are inconsistent or lacking. Similarly, although applying different tDCS protocols to reduce aging-related cognitive impairments by inducing temporary changes in cortical excitability seem somewhat promising, evidence of effects on short- and long-term plasticity is still equivocal. In this article, we will review and critically discuss existing findings of cognitive training- and stimulation-related behavioral and neural plasticity effects in the context of cognitive aging, focusing specifically on working memory and episodic memory functions, which are subserved by the fronto-parietal and hippocampal-striatal networks, respectively. Furthermore, in line with the theory of aging neuronal gain control we will highlight that developing age-specific brain stimulation protocols and the concurrent applications of tDCS during cognitive training may potentially facilitate short- and long-term cognitive and brain plasticity in old age.
133

Les mécanismes de l’inhibition spatiale et non spatiale

Ouerfelli-Éthier, Julie 04 1900 (has links)
Bien que l’inhibition soit souvent considérée comme un concept uniforme, les habiletés d’inhibition se divisent en plusieurs types : l’inhibition spatiale et l’inhibition de réponse. L’inhibition spatiale réfère à l’atténuation de l’interférence de localisations contenant des stimuli saillants et non pertinents. Par exemple, l’inhibition spatiale guide la recherche visuelle de sorte à limiter la visite répétée de localisations déjà explorées. À l’opposé, l’inhibition de réponse est un processus de type moteur et permet l’adaptation du comportement à un contexte changeant lorsqu’un mouvement doit être altéré ou arrêté. Bien qu’il soit admis que les habiletés d’inhibition se subdivisent en plusieurs types, tel que l’inhibition spatiale et l’inhibition de réponse, les différents mécanismes les sous-tendant demeurent mal compris et sous explorés. L’objectif principal de la présente thèse était d’explorer les mécanismes communs et différents de l’inhibition spatiale et l’inhibition de réponse. Particulièrement, les mécanismes de suppression et de facilitation lors de la sélection de la cible furent décrits pour l’inhibition spatiale. De même, la perturbation des habiletés de l’inhibition spatiale et la préservation relative des habiletés d’inhibition de réponse à la suite à de lésions du cortex pariétal postérieur dorsal furent exemplifiées. Finalement, les apports spécifiques du cortex pariétal postérieur dorsal pour l’inhibition spatiale et l’inhibition de réponse furent définis. / While inhibition is often considered a uniform concept, inhibition abilities can be divided in many types: spatial inhibition and response inhibition. Spatial inhibition refers to the attenuation of the interference from locations containing salient and non-pertinent stimuli. For example, spatial inhibition guides visual search to limit the repeated visit of already explored locations. In contrast, response inhibition is motor-based and allows the adaptability of behaviour in a changing context when a movement must be prevented or altered. Although it is widely accepted that inhibition abilities can be divided in many types, such as spatial or response inhibition, the different mechanisms underlying them remain poorly understood and under-explored. The main aim of the present thesis was to explore the common and different mechanisms of spatial and response inhibition. Precisely, the mechanisms of suppression and enhancement during target selection were described during spatial inhibition. The alteration of spatial inhibition processes and the relative preservation of response inhibition abilities in patients with dorsal posterior parietal cortex lesions were also underlined. Finally, the specific contributions of the dorsal posterior parietal cortex for spatial and response inhibition were defined.
134

Recherches sur le système de représentations symboliques de l’art néolithique aux textes des pyramides- Origines et formation des éléments de la religion solaire de l’Egypte antique / Research on the symbolic representations system in Egypt from Neolithic art to the pyramid texts.- Origin and formation of solar religion elements in pharaonic Egypt

Sweydan, Francois 28 February 2011 (has links)
Dès les premières dynasties, le pictogramme fut dans l’écriture le prolongement des représentations figuratives naturalistes, logogrammes dans les palettes funéraires décorées protodynastiques. Ce constat nous porte à les mettre en correspondance avec l’art pariétal du néolithique nubien, le prédynastique égyptien, et celui des aires culturelles périphériques. La reconsidération des pétroglyphes en tant que symboles et idéogrammes, c’est-à-dire des mythogrammes autant que des logogrammes-phonogrammes polysémiques permet de dégager un système structurel de représentations symboliques universel dans la vallée du Nil. Essentiellement funéraire, il est organisé autour d’une nouvelle lecture en relation aux mythes fondateurs de l’Œil d’Horus/solaire, s’exprime dans des rites primitifs de revivification, de renaissance, néolithiques et prédynastiques, explicités ensuite durant les premières dynasties sur des tablettes, des sceaux-cylindres votifs, et l’onction du mort avec les sept huiles canoniques et, enfin, dans les Textes des Pyramides. Contrairement à l’idée commune d’opposition des notions de Nature-Culture, il est question de les conjuguer, de réconcilier la dualité non binaire et de voir, par exemple, les fonctions héliotrope et/ou héliophore des animaux du bestiaire soudanien, avec Sokar le faucon funéraire, les garants bienveillants des métamorphoses et de renaissance du soleil/des défunts, par ailleurs, félidés, canidés, antilopes…, investis du numineux des divinités tutélaires. À la lueur d’une nouvelle lecture du mythe “osirien” primitif de métamorphose, nous reconsidérons les conceptions sur le sacrifice animal sur des bases d’anthropologie religieuse. Loin d’une maîtrise et soumission de la nature, et d’un diffusionnisme, l’interculturalité de la pensée mythique archaïque première dans la vallée nubiano-égyptienne et des régions périphériques multiethniques implique, vis-à-vis du monde naturel et des forces spirituelles numineuses, la transculturalité des conceptions solaires et le partage pluriculturel, transhistorique des croyances résurrectionnelles polycycliques. Ainsi, les pétroglyphes d’animaux, les scènes de chasse animale, les représentations de barques, de sandales, etc., sont de nature funéraire votive, apotropaïque. / Since the beginning of the first dynasties, the pictogram in writing was the extension of naturalistic figurative representations, logograms in the decorated funerary protodynastic palettes. This statement carry us to link them with the parietal art of Neolithic Nubia, the egyptian Predynastic, and peripheral cultural areas. We have reconsidered the petroglyphs as polysemic symbols and ideograms, i.e. mythograms as well polysemic logograms-phonograms, allowing us to draw up a structural system of symbolic representations, universal in the Nile valley. Basically funerary, the system is organised around a new reading in connection with the founding of the ‘Eye of Horus’/solar myths, and express itself in primitive Neolithic and Predynastic rites of revivification, rebirth, more explicit afterwards during the first dynasties on labels, votive cylinder-seals, and anointing the deads with the seven holy canonical oils, finally in the Pyramid Texts. Contrary to the common idea which opposite the Nature-Culture notions, there is some question to combine them, to reconcile the non-binary duality and to see, for example, the heliotrope functions and/or heliophore animals of the sub-Saharan bestiary, with Sokar the funerary hawk, the benevolent guarantors for the rebirth and metamorphosis of the sun/deads; otherwise felids, canids, antelopes…, invested by the numinous of the protecting divinities. In consequence of a new reading of the primitive ‘osirian’ myth of metamorphosis, we have reconsidered the conceptions about animal sacrifice on the basis of religious anthropology. Far from bringing under control and submission of nature, and diffusionnism, the intercultural (cross-cultural) of the first archaic mythic thought in the multi-ethnic nubian-egyptian valley and associated neighbouring areas involves, towards the natural world and the numinous spiritual strengths, the cross-cultural of solar conceptions and multicultural, trans-historic sharing of the polycyclic resurrectional believes. Thus, the animal petroglyphs, cynegetic scenes, boats and sandals representations, etc., are of funerary votive, apotropaic nature.

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