A Network of Face-Sensitive Areas
It is tempting to simplify behaviors by attributing them to a single area of the brain, but repeatedly throughout the text we see examples of behaviors that originate from multiple brain sites. Now researchers have documented that fact with face recognition, using a unique strategy. First, they used fMRI to identify 7 areas in the macaque monkey brain that responded to faces. They then selected 4 of these and found that stimulation of one also initiated activity in the others, indicating that they are not independent but highly networked. Stimulation outside the areas did not have this effect. Science, Vol 320, 1355-1359.
Are You a Synesthete ?
People with synesthesia have cross-modal sensory experiences; that is, stimulation of one sense evokes an experience in another sense as well. The synesthete may "taste" a musical tone or see colors during a symphony, or say that the word "February" is "yellow". We aren't sure why this happens, but the most compelling hypotheses start with the fact that there are many, mostly silent, neural interconnections among the cortical sensory areas. In a You Tube video a synesthete describes how he experiences the world and a researcher tries to make sense of the phenomenon. A second video lets you test yourself for one form of visual/auditory synesthesia.
For Further Reading: Evolution of Color Vision
Almost all non-human mammals are dichromats, meaning that they have two kinds of color receptors, while trichromacy, the ability to distinguish three bands of wavelengths, is common among primates. This Scientific American article traces the evolution of the third receptor that adds immeasurable richness to our visual experience. Some of the material may be difficult to wade through, but it is well worth the effort.
