Neuroscience 2004 Abstract
| Presentation Number: | 824.13 |
|---|---|
| Abstract Title: | Early dorsal stream involvement in object recognition. |
| Authors: |
Dias, E. C.*1
; Sehatpour, P.1
; Javitt, D. C.1
; Foxe, J. J.1
1The Cognitive Neurophysiol. Lab, Nathan Kline Inst, Orangeburg, NY |
| Primary Theme and Topics |
Sensory Systems - Vision -- Visual cortex: Objects and faces |
| Session: |
824. Visual Cortex: Object Recognition Slide |
| Presentation Time: | Wednesday, October 27, 2004 11:00 AM-11:15 AM |
| Location: | San Diego Convention Center - Room 23A |
| Keywords: | Visual Cortex, ERP, fMRI, LOC |
Object recognition is a fundamental mechanism for visually-guided behavior. Functional MRI studies comparing complete images to unrecognizable scrambled versions of those images have shown activation of ventral stream areas, specially of a group of areas known as the lateral occipital complex (LOC). Here we investigated the spatio-temporal dynamics of object recognition by co-registering data from high-density electrical recording (ERPs) and functional magnetic resonance imaging (fMRI).
Nine subjects participated in both ERP and fMRI sessions, during which they were presented with blocks of either complete figures (COM), figures in which 50% of the image had been deleted randomly (INCOMP), or scrambled images (SCRAM). FMRI showed the typical LOC activations but also substantial dorsal stream involvement. Comparison of electrophysiological brain activation under the different conditions showed a surprisingly early and significant differential activation of the P1 component (90-120 ms). This earliest modulation was localized to dorsal stream regions, the same as those seen in the fMRI. This activation was present in both the COM and INCOMP blocks, but not present in the SCRAM condition. There was no difference between the conditions for the N1 component (150-170 ms). Later potentials were localized, as expected, to the LOC.
These results suggest that recognition of an object begins considerably earlier than previously described and initially involves substantial differential processing in dorsal stream visual structures before similar differential processing is seen in the ventral LOC.
Nine subjects participated in both ERP and fMRI sessions, during which they were presented with blocks of either complete figures (COM), figures in which 50% of the image had been deleted randomly (INCOMP), or scrambled images (SCRAM). FMRI showed the typical LOC activations but also substantial dorsal stream involvement. Comparison of electrophysiological brain activation under the different conditions showed a surprisingly early and significant differential activation of the P1 component (90-120 ms). This earliest modulation was localized to dorsal stream regions, the same as those seen in the fMRI. This activation was present in both the COM and INCOMP blocks, but not present in the SCRAM condition. There was no difference between the conditions for the N1 component (150-170 ms). Later potentials were localized, as expected, to the LOC.
These results suggest that recognition of an object begins considerably earlier than previously described and initially involves substantial differential processing in dorsal stream visual structures before similar differential processing is seen in the ventral LOC.
Supported by MH65350, MH63434
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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