Visual attention can be voluntarily focused on a location or automatically attracted by salient features in a visual scene. Studies using functional Magnetic Resonance Imaging (fMRI) suggest two networks of visual attention involved in these complementary mechanisms: a dorsal frontoparietal network and a ventral frontoparietal network of visuospatial attention respectively. However, most studies so far have applied non‐natural schematic stimuli.
The present study investigates visual attention in images of natural environmental scenes. Adopting previously used eye‐tracker paradigms, we study the influence of task instruction and luminance contrast modifications in pictures on both eye movements and neural activity using Eye‐Tracking and functional Magnetic Resonance Imaging simultaneously. We expect increased top‐down control of attention in a search task compared to a free viewing condition visible in enhanced neural activation in the intraparietal sulcus (IPS) as part of the dorsal frontoparietal network. Strong modifications of luminance contrast should foster bottom‐up processing activating the temporoparietal junction (TPJ) a crucial area in the ventral frontoparietal network
of visual attention.
Although the obtained eye‐tracking data shows the expected shift of fixations towards locations of increased luminance contrast, we do not find an influence of luminance contrast modifications on neural processing. Comparison of instructions reveals diverse results across participants possibly due to the long presentation duration of stimuli which allowed participant’s attention to wander independently of task instruction.
We find bilateral activation in IPS and parahippocampal place area (PPA) as well as bilateral deactivation in the TPJ region independent of task context. This might indicate similar contributions of these areas to free viewing of and search in visual scenes. However, dissociation of target detection and attention during search by deconvolution analysis of data obtained in this study might reveal a more detailed picture of functional involvement of the IPS and TPJ region in processes of visual attention. Remarkably, results show robust activation of the PPA in both
tasks, suggesting that the PPA region might not only be activated by houses and open scenes but by narrow scenes (bushes, leaves) of natural outdoor environment as well.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa.de:bsz:14-qucosa-24939 |
| Date | 28 October 2009 |
| Creators | Petzold, Antje |
| Contributors | Universität Osnabrück, Institute of Cognitive Science, Prof. Dr. Peter König, Prof. Dr. Peter König, Prof. Rainer Goebel |
| Publisher | Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:masterThesis |
| Format | application/pdf |
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