Neural mechanisms involved in the processing of global and local aspects of hierarchically organized visual stimuli.

Details

Serval ID
serval:BIB_3BF94BAD10BB
Type
Article: article from journal or magazin.
Collection
Publications
Title
Neural mechanisms involved in the processing of global and local aspects of hierarchically organized visual stimuli.
Journal
Brain
Author(s)
Fink G.R., Halligan P.W., Marshall J.C., Frith C.D., Frackowiak R.S., Dolan R.J.
ISSN
0006-8950 (Print)
ISSN-L
0006-8950
Publication state
Published
Issued date
1997
Volume
120 ( Pt 10)
Pages
1779-1791
Language
english
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov'tPublication Status: ppublish
Abstract
We investigated the functional anatomy involved in sustaining or switching visual attention between different perceptual levels, using functional imaging measures of neural activity. Two experiments were carried out using hierarchically organized letters (i.e. large letters made out of small letters). In a divided-attention task, subjects were required to switch attention between local and global levels. The number of successive stimuli for which subjects had to sustain attention to either the global or local level co-varied significantly with temporal-parietal activations bilaterally. Other activations were also observed in the right orbitofrontal cortex, the right dorsolateral prefrontal cortex, and the right middle temporal gyrus. The number of switches between levels co-varied significantly with activations in the left supplementary motor area and the left medial parietal cortex. In the directed-attention task, subjects were required to attend to either the global or local level of the stimuli throughout all trials; attention to the global aspect resulted in significant activation of the right lingual gyrus while attention to the local aspect significantly activated the left inferior occipital cortex. We suggest that left hemisphere activations with increasing numbers of switches between perceptual levels reflect increased demands on an executive attentional system, while sustained attention to either level activates a predominantly right hemispheric network involving temporal-parietal and dorsolateral prefrontal regions. Overall, the results provide evidence for relative hemispheric specialization for global and local processing in accordance with previous neuropsychological studies. In addition, the findings demonstrate that early visual processing mechanisms in the prestriate cortex are influenced by an attentional system in temporal-parietal areas.
Keywords
Adult, Attention/physiology, Brain/anatomy & histology, Brain/physiology, Functional Laterality/physiology, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Photic Stimulation/methods, Tomography, Emission-Computed, Visual Perception/physiology
Pubmed
Web of science
Open Access
Yes
Create date
16/09/2011 16:35
Last modification date
20/08/2019 13:32
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