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Journal Article

The Effect of image scrambling on visual cortical BOLD activity in the anesthetized monkey

MPS-Authors
http://pubman.mpdl.mpg.de/cone/persons/resource/persons84154

Rainer,  G
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

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

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

Rainer, G., Augath, M., Trinath, T., & Logothetis, N. (2002). The Effect of image scrambling on visual cortical BOLD activity in the anesthetized monkey. Neuroimage, 16(3A), 607-616. doi:10.1006/nimg.2002.1086.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0013-DF84-8
Abstract
We have investigated BOLD signal changes associated with scrambling natural images into different numbers of segments in visually modulated regions of the macaque monkey (macacca mulatta) brain. For 10° × 10° images, we observed that BOLDactivity in primary visual cortex (V1) increased with scrambling, and then dramatically dropped for very highly scrambled images (128 × 128 segments). In extrastriate visual areas, BOLD signal levels did not distinguish between natural images and scrambled images, except that as in V1 very highly scrambled images led to a drop in BOLDactivity. Finally in the superior temporal sulcus region and inferior temporal cortex, BOLDactivity decreased systematically with scrambling. Our results are consistent with the view that the BOLD signal might reflect average activation of local orienation detectors in V1, and sensitivity to more global object representations in higher visual areas. In addition, we quantify the effects of scrambling on the Fourier amplitude spectrum of the images. This analysis shows that scrambling causes substantial changes to the spatial frequency content of images. This suggests that low-level accounts for reduced BOLD activation in higher visual areas cannot be completely ruled out based on scrambling data.