January 22, 2011

When I see your Face, there’s not a thing that I would change... By Patrick N. Rabanal

‘Coz girl you’re amazing just the way you are.

Don’t you feel like just melting when you see the face of your crush? May it be while walking along the corridors or seeing a picture of that person. You may not know it, but there are a lot of different parts in your brain that work together, to really “see” that face.
In class we discussed how different areas of the brain were involved in face perception: the occipital cortex for initial processing, the fusiform gyrus for identification, the amygdale for emotional aspects, the superior temporal sulcus for gaze direction, and the frontal area for evaluating attractiveness. This supports the idea of distributed coding or representation of images like a face, in the brain.
In Perception of Face Parts and Face Configurations: An fMRI Study, Jia et al., focused on three areas that responded selectively to faces: the occipital face area (OFA), the fusiform face area (FFA), and a face-selective region in the superior temporal sulcus (fSTS). They looked into how these parts responded to two important aspects of face perception, faces parts (eyes, nose, and mouth) and the T-shaped spatial configuration of these parts. Using the Region-of-Interest approach, where each subject was pretested to find specific areas of the brain, the experimenters were able to identify the location of these three parts. For the experiment, they used photographs of faces that were manipulated, having face parts or not, and having different configurations (T-shaped face configuration or scrambled). Brain activity in these regions was measured with every stimulus presented.
Results show that the OFA and the fSTS are sensitive to the presence of face parts in the stimulus but not to the presence of a veridical T-shaped face configuration, whereas the FFA is sensitive to both kinds of information. Further, only in the FFA is the response to configuration and part information correlated across voxels, implying that the FFA contains a unified representation that includes both kinds of information. Consistent with other studies, they found that OFA is not only activated by but is also necessary for the analysis of face parts. It gave them the idea that it conducts a relatively early stage of face processing, earlier than the FFA. This suggests that the FFA and the OFA comprise a hierarchical network for face perception with the FFA inheriting the part sensitivity of the OFA, and then further integrating or elaborating this information to include sensitivity to the spatial configuration of these parts.
Much like the OFA, the fSTS was sensitive only to face parts, not face configurations. This finding is generally consistent with previous studies that associate this region with the discrimination of gaze direction and expression.
This is just another evidence of distributed representation of visual images in the brain. Aside from just seeing your crush and suddenly feeling bubbly, we now know that there are many areas of the brain involved in perceiving faces
 Aside from this, it makes me wonder what the difference would be in brain activity seeing faces that are attractive and those that are not or how can the frontal area tell us what is attractive and what isn’t.

Jia, L., Harris, A., & Kanwisher, N. (2010). Perception of Face Parts and Face Configurations: An fMRI Study. Journal of Cognitive Neuroscience, 22(1), 203-211.
Photo from: http://www.flickr.com/photos/dominiquejames/458812863/

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