COGNITIVE NEUROSCIENCEHierarchical visual processing is dependent on the oculomotor systemWeber, Bruno3; Schwarz, Urs1; Kneifel, Stefan1; Treyer, Valerie1; Buck, Alfred1Author Information 1Department of Neurology, Universitätsspital, Frauenklinikstrasse 26, CH-8091 Zürich, Switzerland 2Division of Nuclear Medicine, Universitätsspital, Frauenklinikstrasse 26, CH-8091 Zürich, Switzerland 3Corresponding Author: Bruno Weber Received 6 October 1999; accepted 7 November 1999 Acknowledgements: We thank Caroline Kertzman for discussions and comments that helped to improve the manuscript, Gustav K. von Schulthess for providing the fMRI infrastructure and Dorothea Weniger for important suggestions. NeuroReport: February 7, 2000 - Volume 11 - Issue 2 - p 241-248 Buy Abstract Using functional MRI and eye movement recordings we studied the processing of hierarchical stimuli. In agreement with others, we found a minor left hemispheric dominance during local and right dominance during global processing. When attention was directed locally, well-known oculomotor cortical areas were activated, and saccades were elicited in 41% of the trials. Their latencies were similar to pro-saccades. During global processing virtually no saccades occurred. These results suggest two different operational modes of attention. Attending to local features induces a shift of attention, which simultaneously computes a saccade on any level above the brainstem with a computational burden equal to reflexive saccades. Conversely, attending to global features induces an expansion of the focus of attention, which reinforces fixation. © 2000 Lippincott Williams & Wilkins, Inc.