The complexity [of speech] comes from the fact that spoken words require the coordinated efforts of numerous "articulators" in the vocal tract -- the lips, tongue, jaw and larynx -- but scientists have not understood how the movements of these distinct articulators are precisely coordinated in the brain. To understand how speech articulation works, Chang and his colleagues recorded electrical activity directly from the brains of three people undergoing brain surgery at UCSF, and used this information to determine the spatial organization of the "speech sensorimotor cortex," which controls the lips, tongue, jaw, larynx as a person speaks. This gave them a map of which parts of the brain control which parts of the vocal tract. They then applied a sophisticated new method called "state-space" analysis to observe the complex spatial and temporal patterns of neural activity in the speech sensorimotor cortex that play out as someone speaks. This revealed a surprising sophistication in how the brain's speech sensorimotor cortex works. They found that this cortical area has a hierarchical and cyclical structure that exerts a split-second, symphony-like control over the tongue, jaw, larynx and lips.Okay, so getting a real-time map of what happens in the sensori-motor area is an advance in scanning. But really: why are you surprised at the sophistication? It's been known for 200 years that speech is a monstrously complex process involving split-second coordination of a dozen major sections of the body and a hundred different muscles. So the control center, wherever it might be, has to provide split-second coordination of a monstrously complex process. Considering the brain's even more amazing ability to rewire itself on the fly, I doubt that these particular mappings are permanent or general.
Polistra was named after the original townsite of Manhattan (the one in Kansas). When I was growing up in Manhattan, I spent a lot of time exploring by foot, bike, and car. I discovered the ruins of an old mill along Wildcat Creek, and decided (inaccurately) that it was the remains of the original site of Polistra. Accurate or not, I've always liked the name, with its echoes of Poland (an under-appreciated friend of freedom) and stars. ==== The title icon is explained here. ==== Switchover: This 2007 entry marks a sharp change in worldview from neocon to pure populist. ===== The long illustrated story of Polistra's Dream is a time-travel fable, attempting to answer the dangerous revision of New Deal history propagated by Amity Shlaes. The Dream has 8 episodes, linked in a chain from the first. This entry explains the Shlaes connection.