Saturday, March 5, 2011

Are You Learning English? These Songs May Help

Language bootstrapping the brain

Marina Bedny and colleagues [1] show that, to a remarkable degree, the visual cortex of blind subjects takes on language-specific processing tasks.
I think the paper makes a nice occasion to consider just how language-specific areas of the left hemisphere may have evolved. The fact that one of the most domain-specific cortical regions of the brain can, to some degree, be reprogrammed to support language processing suggests that language itself is surprisingly voracious in its ability to consume brain resources and redirect development.
I'm a little surprised that we didn't already know that blind subjects use visual cortex in language. It has the ring of previous scholarship. And actually the authors discuss a boatload of previous studies that appear to show precisely that: blind subjects relying upon visual cortex for language processing. The visual cortex increases activity during language tasks in blind subjects; blind subjects who have their occipital lobes zapped with transcranial magnetic pulses have problems performing language tasks, and visual cortex activity in blind subjects appears to be correlated with verbal memory. But Bedny and colleagues discuss several reasons why the previous results were not fully convincing; the visual cortex might be taking on domain-general or sensory cognitive tasks instead of language processing proper.
Bedny and colleagues devised a series of tests involving different language tasks, showing that the visual cortex in blind subjects responded not merely to difficult or memory-intensive tasks, but specifically to those tasks that most tax the language regions of normal subjects. The simplest interpretation is that the visual cortex has indeed taken on language-specific functions in blind subjects.
Below: How language eats brains, and why it matters to language evolution.
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