Räumliche Aufmerksamkeitsausrichtung und Alertness: Interaktion zweier Aufmerksamkeitsnetzwerke?
Current neuropsychological theories of attention postulate the existence of different attention systems, which are implemented anatomically in form of discrete functional networks. These networks are considered to operate autonomously to some extent, but also to interact during the execution of certain cognitive tasks. Some authors, among them Posner and his co-workers in particular, formulated hypotheses about specific interactions of these attention networks. The present work examines such an hypothesis regarding the attentional functions of alertness and visuospatial orienting of attention in two empirical studies from different perspectives. The first empirical part of this work was aimed at the analysis and comparison of the functional anatomy of alertness and (overt as well as covert) visuospatial orienting of attention in the healthy brain. An fMRI-study with ten normal subjects revealed highly overlapping brain areas activated by both attentional functions. Specific activations attributable to visuospatial orienting of attention could be shown exclusively in superior parietal regions of both hemispheres. The neuropsychological syndrome of hemispatial neglect manifesting in a failure to respond to information located in the contralesional half space is attributed to a distortion of visuospatial orienting of attention by most current explanation models. An increasing number of findings reporting a co-variation of chronic unilateral neglect symptoms following right hemisphere lesions with additional alertness deficits can be interpreted as yet another piece of evidence of a close relationship between the two attentional functions. In order to examine the hypothesis of a causal link, a single case study was conducted in the second empirical part of this work to test whether an improvement of the general activation level due to a specific alertness training results in a decrease of chronic neglect symptoms. The results indeed indicate a beneficial effect of the alertness therapy on the neglect symptoms of the tested patient, concerning both neuropsychological behavioral data and cerebral functional reorganisation processes. The findings support the idea that the anterior alerting network co-activates, either directly or via the brainstem, the posterior attention system in the parietal cortex involved in spatial orienting of attention. Implications for the rehabilitation of hemispatial neglect are discussed.
info:eu-repo/classification/ddc/150, Psychologie, räumliche Aufmerksamkeitsausrichtung, Alertness, Aufmerksamkeitsnetzwerke, Neglect
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