Neuroscience 2005 Abstract
| Presentation Number: | 934.3 |
|---|---|
| Abstract Title: | Cortical mechanisms underlying contextual facilitation of visual object recognition. |
| Authors: |
Fenske, M. J.*1
; Bar, M.1
1MGH, Harvard Med. School, Charlestown, MA |
| Primary Theme and Topics |
Cognition and Behavior - Human Cognition, Behavior, and Anatomy -- Perception and imagery |
| Session: |
934. Perception and Imagery V Slide |
| Presentation Time: | Wednesday, November 16, 2005 1:30 PM-1:45 PM |
| Location: | Washington Convention Center - Room 144A |
| Keywords: | CONTEXT, TEMPORAL LOBE, FMRI, VISUAL CORTEX |
Recognizing an object is usually faster and more accurate if that object has been encountered previously. Such experience-based priming of recognition can also be achieved through context-specific predictions about which objects are likely to appear together in a specific scene. Seeing a toaster, for instance, can facilitate subsequent recognition of contextually related objects such as a coffee-maker and a blender. The benefit of priming during recognition is typically associated with a physiological response reduction in occipito-temporal cortex. Moreover, the specific regions that exhibit response reduction in priming tasks can vary according to the nature of the relation between the target- and preceding prime-objects. Using event-related fMRI, we sought to elaborate the cortical mechanisms involved in experience-based facilitation of object recognition. Thus, we compared the different foci of response reductions for targets preceded by primes that were either the same object or were contextually related (but perceptually different). Priming in both cases was reflected by improvements in RT and a reduced fMRI signal relative to that for novel objects. Contextual facilitation increased with the strength of prime-target contextual relations, and was associated with response reduction in bilateral regions of parahippocampal cortex shown recently to mediate contextual analysis (Bar & Aminoff, 2003). Perceptual (repetition-related) facilitation was associated with reductions in bilateral mid-fusiform and occipito-temporal cortices, reflecting item specific effects. Response reductions were observed for both repetition and contextual priming in left anterior fusiform, inferior frontal and lateral occipital cortices. The contextually mediated response reduction in these object processing regions suggests that contextual facilitation of object recognition is mediated by sensitizing the representations of contextually related objects in occipito-temporal regions. These findings converge to further inform our formulation of a model of top-down contextual facilitation in object recognition.
Support: NINDS R01NS44319/050615.
Support: NINDS R01NS44319/050615.
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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