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FMRI Correlates of Perceptual Filling-in in a Moving Random Dot Paradigm

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http://pubman.mpdl.mpg.de/cone/persons/resource/persons84007

Keliris,  GA
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons84972

Smirnakis,  SM
Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons84023

Kourtzi,  Z
Department Human Perception, Cognition and Action, Max Planck Institute for Biological Cybernetics, Max Planck Society;
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons84260

Tolias,  AS
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

Keliris, G., Smirnakis, S., Kourtzi, Z., Tolias, A., & Logothetis, N. (2002). FMRI Correlates of Perceptual Filling-in in a Moving Random Dot Paradigm. Poster presented at 32nd Annual Meeting of the Society for Neuroscience (Neuroscience 2002), Orlando, FL, USA.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0013-DE8B-2
Abstract
Perceptual filling-in refers to the fading of stabilized retinal patterns and their replacement by non-stabilized surrounding patterns. We used functional magnetic resonance imaging (fMRI) to investigate neuronal correlates of perceptual filling-in induced by a dynamic random dot pattern. The stimulus consisted of a moving random dot pattern on dark background surrounding a region devoid of dots (artificial scotoma). The subjects fixated at an eccentrically located spot, and they reported the time of onset of filling-in by button press. We controlled for attention by dimming the fixation spot at random points in time, which the subjects reported via a separate button press. Catch trials in which the stimulus physically filled the artificial scotoma were interspersed with filling-in trials to gauge the subjects’ performance. General linear model techniques with appropriate predictors were used to define areas of interest for analysis. Filling-in trials for each subject were divided in two groups of 30 trial s each, based on whether filling in occurred earlier (lt;8 s) or later (8-24 s) in a trial. The stimulus was identical for all trials. Preliminary results suggest that the fMRI signal from area V1 rises initially in both groups but then dips and remains low for the group with early filling-in. This suggests that filling-in is associated with a relative suppression of cortical activity. Other interpretations will be discussed.