Have you ever seen the man in the moon? How about faces in rocks and trees? The brain is wired to find and focus on faces.In a study lead by neurobiologists from Harvard Medical Center (published in Science) titled, "A Cortical Region Consisting Entirely of Face-Selective Cells," it was observed that;
"Face perception is a skill crucial to primates. In both humans and macaque monkeys, functional magnetic resonance imaging (fMRI) reveals a system of cortical regions that show increased blood flow when the subject views images of faces, compared with images of objects. However, the stimulus selectivity of single neurons within these fMRI-identified regions has not been studied. We used fMRI to identify and target the largest face-selective region in two macaques for single-unit recording. Almost all (97%) of the visually responsive neurons in this region were strongly face selective, indicating that a dedicated cortical area exists to support face processing in the macaque."
So what we're looking at is a whole chunk of your brain that only lights up in response to a face. Now, if you think about it, looking at a picture of a face isn't tremendously different from looking at one of an apple; in both cases your visual centers perceive shape and colour/texture. That said, anyone can tell you that a face has much more (and more important) information than an apple. The brain has developed this face-sensitive area to a) make it harder for us to confuse faces for things, and b) to recognize when someone is looking at you.
Both of these functions make sense. You won't survive for long of you can't recognize the tigers face through the bushes or tell if he is, in fact, looking at you. In my "Minds and Brains" class we looked at other studies that have observed a related area of the brain in chimpanzees during facial recognition tasks, and they found that there are neurons that are specifically sensitive to recognizing faces at different angles (a neuron per degree from center, or something along those lines). Also, yet further studies indicate that the biggest keys to recognizing a face are the eyes. In this study they observed a dramatic increase in brain activity (in this area of interest) when eyes were added to an otherwise complete face.
http://anthropology.net/user/kambiz_kamrani/blog/2006/02/07/face_recognition_brain_maturation_and_mirror_neurons
http://www.sciencedaily.com/releases/1999/06/990624080203.htm
2 comments:
Wow, fascinating. So basically,face-blind people are missing that entire cortical region. Like, I'm missing a big chunk out of my brain. I think in my case there's a beach resort there, and the cortices only come out when they get tired of Red Stripe and jerk chicken or something. Because SOMETIMES I recognize faces just fine, but other times...it's not so pretty.
I wouldn't jump to the conclusion that face-blindness equals a missing part of your brain (I'm still doing research on that one, so we'll see if we can't get some kind of answer for you). I wouldn't put it past you to have an entire brain AND a beach resort in that noggin of yours, you've always got so much going on up there... though that's not at all scientific.
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