January 10, 2006 | vol. 103 | no. 2 | 449–454 | M. Bar*, K. S. Kassam*§$, A. S. Ghuman*§$, J. Boshyan*, A. M. Schmid*, A. M. Dale*, M. S. Hämäläinen*, K. Marinkovic*, D. L. Schacter*, B. R. Rosen*, and E. Halgren*
The study investigates the role of top-down facilitation in visual object recognition, focusing on the orbitofrontal cortex (OFC) and its interaction with the temporal cortex. Traditional views suggest that visual processing follows a bottom-up hierarchy, but recent proposals highlight the importance of top-down processing. The authors test a specific model that proposes low spatial frequencies (LSFs) facilitate visual object recognition by initiating top-down processes from the OFC to the visual cortex. Using magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI), they found that differential activity related to successful object recognition developed earlier in the OFC (50 ms) compared to the temporal cortex. This early OFC activity was modulated by LSFs in the image. Additionally, phase-locking analysis revealed strong synchrony between the OFC, fusiform gyrus, and early visual areas, supporting the idea of feed-forward and feedback projections. The results provide strong support for the proposed model and suggest that the OFC plays a more active role in object recognition than previously thought.The study investigates the role of top-down facilitation in visual object recognition, focusing on the orbitofrontal cortex (OFC) and its interaction with the temporal cortex. Traditional views suggest that visual processing follows a bottom-up hierarchy, but recent proposals highlight the importance of top-down processing. The authors test a specific model that proposes low spatial frequencies (LSFs) facilitate visual object recognition by initiating top-down processes from the OFC to the visual cortex. Using magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI), they found that differential activity related to successful object recognition developed earlier in the OFC (50 ms) compared to the temporal cortex. This early OFC activity was modulated by LSFs in the image. Additionally, phase-locking analysis revealed strong synchrony between the OFC, fusiform gyrus, and early visual areas, supporting the idea of feed-forward and feedback projections. The results provide strong support for the proposed model and suggest that the OFC plays a more active role in object recognition than previously thought.