Suchergebnisse

This dissertation investigates white matter fiber pathways for phonological transformation processes which were tracked by diffusion tensor imaging (DTI) in a large-scale language network which was functionally defined by a functional magentic resonance imaging (fMRI) experiment investigating different phonological transformation processes in German. In the fMRI study two types of phonological transformation were performed by subjects in the scanner, a suprasegmental transformation task in which a pseudo-country had to be transformed into a pseudo-language which required a shift of stress placement. In a segmental transformation task, in turn, a vowel segment change was elicited by having subjects transform a pseudo-noun into a pseudo-diminutive, or vice-versa. DTI images were acquired from 20 subjects (mean age=34 y, range=20-69 y, 8 females). Language areas were defined based on the results from the fMRI experiment contrasting suprasegmental and segmental transformation, respectively, with repetition. Fronto-parietal as well as interhemispheric pathways between these functionally defined core-regions were tracked with a probabilistic diffusion-tensor based imaging method. Connectivity between areas active during suprasegmental transformation, that is left inferior parietal lobule (IPL), intraparietal sulcus (IPS) and left inferior frontal gyrus (IFG), pars opercularis (BA 44) was provided by a dorsal pathway via the arcuate fascicle (AF) and superior longitudinal fascicle (SLF) fiber system. Areas active during segmental transformation, namely IPL, IPS and IFG, pars triangularis (BA 45) are connected in both hemispheres by a ventral pathway via the extreme capsule (EmC), while IPL and IFG (BA 44) are connected by a dorsal pathway via the AF/SLF fiber system. The segregation of language related white-matter pathways into dorsal and ventral pathways (Saur et al., 2008) suggests a functio-anatomical dissociation for different processing routines. For phonological processing, the dorsal pathway seems to act as a fast, bottom-up route for mapping suprasegmental and segmental phonemic information from phonological short-term store in IPL to the inferior-frontal articulatory network, whereas the ventral pathway could be important for top-down modulation based on lexical-semantic information. It will be interesting to further investigate, how disruptions of particular subcomponents of this parieto-frontal network and the connecting dorsal and ventral pathways affects specific processing routines, like phonological transformation processes. ; In der vorliegenden Arbeit werden mittels probabilistischer Traktographie die Faserverbindungen zwischen kortikalen Arealen für phonologische Verarbeitung, welche durch ein Sprachexperiment mittels funktioneller Kernspintomographie (fMRT) definiert wurden, untersucht. Die Ergebnisse zeigen, dass phonologische Transformationsprozesse in einem Netzwerk mit zwei unterschiedlichen Verbindungswegen für die Interaktion zwischen frontalen und parietalen Arealen verwirklicht werden. Ein dorsaler Weg über das Fasersystem des Fasciculus arcuatus und Fasciculus longitudinalis superior verbindet inferior-parietale Areale links mit dem linken Gyrus frontalis inferior, Brodmann-Areal (BA) 44 und ein ventraler Weg über das Fasersystem der Capsula extrema verbindet inferior-parietale Areale links mit dem linken Gyrus frontalis inferior, BA 45. Die beiden Fasersysteme zeigen eine funktionelle Segregierung, wobei der dorsale Weg hinreichend für phonologische Transformation basierend auf einer Betonungsverschiebung (suprasegmentale Transformation) ist und der ventrale Weg notwendig für phonologische Transformation welche auf Segmentierung basiert (segmentale Transformation) ist. Hinsichtlich der neurokognitiven Prozesse ist anzunehmen, dass der dorsale Weg vorwiegend als schnelle, sogenannte "bottom-up", Route für das Weiterleiten segmentaler und suprasegmentaler phonemischer Information dient, während der ventrale Weg eine Route für die exekutive Modulation, oder "top-down" Kontrolle, mittels lexikalisch-semantischer Information darstellt. Die ebenfalls untersuchten interhemisphärischen Faserverbindungen zwischen kortikalen Arealen für phonologische Transformation zeigen, dass transkallosale Projektionsfasern homotope Areale (z.B. BA 44 links mit BA 44 rechts) direkt miteinander verbinden. Auf der neurokognitiven Ebene kann die Interaktion zwischen homotopen Arealen, insbesondere inferior frontal, wichtig für unterschiedliche Arten prosodischer Störungen infolge eines neurologischen Schadens sein.

The paper introduces the notion of 'digital behavioral technologies' and discusses them from the perspectives of vulnerability and justice, thereby integrating perspectives from bioethics or public health ethics and political philosophy. Digital behavioral technologies have seen a massive uptake in recent years, but the market for them is hardly regulated. We argue that understanding the impact of digital behavioral technologies requires understanding individuals not as abstract, atomized agents, but rather to take their embeddedness into social structures into account. This also allows extending the focus to groups, relationships and whole societies, which are often structurally unjust. This perspective provides a corrective to an overly individualistic consideration of digital behavioral technologies, which may suggest itself because of their focus on individual bodies. We point out some implications of this integrated approach with regard to the regulation of digital behavioral technologies. We conclude by describing some implications both for those who work on digital behavioral technologies and for those who work on questions of vulnerability and justice.