کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
945167 925762 2009 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Evidence for long-range feedback in target detection: Detection of semantic targets modulates activity in early visual areas
موضوعات مرتبط
علوم زیستی و بیوفناوری علم عصب شناسی علوم اعصاب رفتاری
پیش نمایش صفحه اول مقاله
Evidence for long-range feedback in target detection: Detection of semantic targets modulates activity in early visual areas
چکیده انگلیسی

In a variety of attention and search tasks, single-cell recordings of the primate brain have frequently shown an enhancement of responses in early visual areas to selected target stimuli. This enhancement is observed only at longer latencies, suggesting the possibility that it reflects the action of feedback or return signals from upstream processing areas. However, in typical studies, targets are specified on the basis of elementary visual features; as these are coded at multiple levels of the visual system, it is impossible to determine where enhanced target processing begins. Using human functional magnetic resonance imaging (fMRI), we demonstrate enhancement of activity in early visual areas even when low-level visual information is insufficient for target detection to occur. We found enhanced activity in early visual areas to targets defined purely by semantic category, suggesting that feedback signals returning from at least as far forward as temporal lobe semantic processing can influence visual responses. These findings also suggest feedback signaling as a mechanism by which early and late brain systems coding for different properties of a target object can integrate their activity, allowing for the target object to dominate overall processing.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Neuropsychologia - Volume 47, Issue 7, June 2009, Pages 1721–1727
نویسندگان
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