| Stimulus-dependent modulation of suppressive influences in MT. | |
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MedLine Citation:
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PMID: 21228177 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Surround suppression contributes to important functions in visual processing, such as figure-ground segregation; however, this benefit comes at the cost of decreased neuronal sensitivity. Studies of receptive fields at several levels of the visual hierarchy have demonstrated that surround suppression is reduced for low contrast stimuli, thereby improving neuronal sensitivity. We investigated whether this reduction of surround suppression reflects a general processing strategy to boost sensitivity for weak signals by summing them over a larger region of the visual field (spatial integration) or if the reduction is limited to specialized stimulus conditions. To do this, we used stochastic motion stimuli to measure surround suppression in area MT of alert macaque monkeys. While varying stimulus size we also varied the strength of two other critical stimulus features: contrast and coherence (i.e., the proportion of dots moving in the preferred direction of the neuron). We found that reducing stimulus contrast weakened surround suppression, but reducing stimulus coherence had the opposite effect, indicating that diminished surround suppression is not a universal response to stimuli of low signal-to-noise. This can be partially explained by our other finding, which is that surrounds in MT are very broadly direction tuned. Instead of producing a reduction of surround suppression that would improve the ability of the neuron to integrate preferred direction motion, low coherence stimuli activated the broadly tuned surrounds relatively better than the centers, which are generally more direction selective. Our results are consistent with a normalization mechanism of surround suppression that pools broadly across multiple stimulus dimensions. |
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Authors:
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J Nicholas Hunter; Richard T Born |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of neuroscience : the official journal of the Society for Neuroscience Volume: 31 ISSN: 1529-2401 ISO Abbreviation: J. Neurosci. Publication Date: 2011 Jan |
Date Detail:
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Created Date: 2011-01-13 Completed Date: 2011-02-22 Revised Date: 2012-03-07 |
Medline Journal Info:
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Nlm Unique ID: 8102140 Medline TA: J Neurosci Country: United States |
Other Details:
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Languages: eng Pagination: 678-86 Citation Subset: IM |
Affiliation:
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Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Contrast Sensitivity Macaca mulatta Male Motion Perception* Neurons / physiology Photic Stimulation Stochastic Processes Visual Cortex / physiology* |
| Grant Support | |
ID/Acronym/Agency:
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EY11379/EY/NEI NIH HHS; EY12196/EY/NEI NIH HHS; R01 EY011379-13/EY/NEI NIH HHS; R01 EY011379-15/EY/NEI NIH HHS; T32 MH020017-12/MH/NIMH NIH HHS |
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