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Using glass patterns and fMRI to identify areas that process global form in macaque visual cortex

MPS-Authors
http://pubman.mpdl.mpg.de/cone/persons/resource/persons84264

Tse,  PU
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons83787

Smith MA, Augath,  M
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons84262

Trinath,  T
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons84063

Logothetis,  NK
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

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Citation

Tse, P., Smith MA, Augath, M., Trinath, T., Logothetis, N., & Movshon, J. (2001). Using glass patterns and fMRI to identify areas that process global form in macaque visual cortex. Poster presented at 31st Annual Meeting of the Society for Neuroscience (Neuroscience 2001), San Diego, CA, USA.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0013-E1DD-2
Abstract
The goal of these experiments is to locate areas of the macaque brain involved in processing global form. For this purpose, natural objects are not ideal stimuli because their form-defining characteristics are difficult to isolate, parameterize, or control. Glass patterns, created by pairing each dot in a random texture with another at a specified spatial offset (Glass 1969, Nature), are useful because form is defined by the global statistics of dot placement with spatial correlations that are purely local. Recently, Wilson et al (1997, Vision Research) showed that concentric Glass patterns are processed more efficiently than other patterns with the same local but differing global statistics, suggesting that there exist higher-order ‘grouping‘ filters tuned to particular patterns of activation among local filters. We generated static and dynamic Glass patterns with different global forms, and used these to activate visual cortex in anesthetized monkeys. We measured the resulting BOLD fMRI signals in a 4.7T/40cm Biospec vertical scanner (Bruker, Inc), with 50mT/m gradients, using quadrature transmit/receive RF coils. Voxel volume was 0.5x0.5x2mm, TE=20ms, TR=750ms, and FA=40deg. We collected multi-shot, multi-slices T2* weighted images (13 horizontal slices) of the entire brain using gradient-recalled EPI fMRI sequences. We found significant signal differences between coherent Glass patterns and randomly oriented dot pairs in V2 and other areas. This suggests that grouping mechanisms and filters tuned to global form relationships among dots are located in these areas, but not in V1.