This title appears in the Scientific Report :
2008
Please use the identifier:
http://hdl.handle.net/2128/3142 in citations.
Visuospatial attention: Neural Correlates and Pharmacological Modulation in Healthy Subjects and Patients with Spatial Neglect
Visuospatial attention: Neural Correlates and Pharmacological Modulation in Healthy Subjects and Patients with Spatial Neglect
The detection of relevant stimuli occurring outside of the current focus of attention is an essential cognitive ability of both animals and humans. The present thesis concentrates on the neural and neurochemical mechanisms in the human brain that underlie the processing of unattended stimuli requiri...
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Personal Name(s): | Vossel, Simone (Corresponding author) |
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Contributing Institute: |
Institut für Neurowissenschaften und Biophysik - Medizin; INB-3 |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2008
|
Physical Description: |
XIV, 176 S. |
Dissertation Note: |
Universität Oldenburg, Diss., 2008 |
ISBN: |
978-3-89336-526-5 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
Funktion und Dysfunktion des Nervensystems |
Series Title: |
Schriften des Forschungszentrums Jülich : Gesundheit / Health
7 |
Subject (ZB): | |
Link: |
OpenAccess |
Publikationsportal JuSER |
The detection of relevant stimuli occurring outside of the current focus of attention is an essential cognitive ability of both animals and humans. The present thesis concentrates on the neural and neurochemical mechanisms in the human brain that underlie the processing of unattended stimuli requiring reorienting of visuospatial attention. To study these processes, Posner’s location-cueing paradigm (Posner, 1980) was employed. Here, spatial cues predict the location of a behaviourally relevant target stimulus with a certain probability and the difference in reaction times between invalidly and validly cued targets (termed the ‘validity effect’) is taken as an indicator for the speed of reorienting of attention. Functional magnetic resonance imaging (fMRI) in combination with psychopharmacology was used to investigate the reorienting-related neural systems in the brain. This thesis is concerned with the question how the neural processes of attentional reorienting are modulated by cognitive as well as by pharmacological factors. Prior studies have shown that attentional reorienting is one cognitive function that can be modulated pharmacologically by cholinergic agents. In the location-cueing paradigm the administration of the cholinergic agonist nicotine leads to faster reaction times to invalidly cued targets and consequently to a decreased validity effect (e.g., Witte, Davidson & Marrocco, 1997). This behavioural effect is accompanied by a reduction of reorienting-related neural activity in the parietal cortex (Thiel, Zilles & Fink, 2005). Drug-induced changes in the processing of the probabilistic top-down information of the spatial cues about the target location have been proposed to underlie this pharmacological effect (Yu & Dayan, 2005). Thus, a first aim of the present thesis was to study how reorienting towards unattended events can be manipulated by the top-down information about their location (i.e., by cue validity) and how the effects of this cognitive modulation are represented in the brain in a placebo condition. It was observed that the effects of a cue validity manipulation resembled the effect of nicotine in the location-cueing paradigm, since low cue validity (60%) decreased the validity effect as well as reorienting-related neural activity in right frontal and parietal cortex when compared to a high cue validity condition (90%). A further aim of the thesis was to examine the interaction effects between the cognitive and the pharmacological modulation of attentional reorienting at the behavioural as well as the neural level. Given that nicotine is supposed to reduce the [...] |