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あらすじ・解説
Using language is a complex business. Let's say you want to understand a sentence. You first need to parse a sequence of sounds—if the sentence is spoken—or images—if it's signed or written. You need to figure out the meanings of the individual words and then you need to put those meanings together to form a bigger whole. Of course, you also need to think about the larger context—the conversation, the person you're talking to, the kind of situation you're in. So how does the brain do all of this? Is there just one neural system that deals with language or several? Do different parts of the brain care about different aspects of language? And, more basically: What scientific tools and techniques should we be using to try to figure this all out? My guest today is Dr. Ev Fedorenko. Ev is a cognitive neuroscientist at MIT, where she and her research group study how the brains supports language and complex thought. Ev and her colleagues recently wrote a detailed overview of their work on the language network—the specialized system in our brain that underlies our ability to use language. This network has some features you might have expected, and—as we’ll see—other features you probably didn't. Here, Ev and I talk about the history of our effort to understand the neurobiology of language. We lay out the current understanding of the language network, and its relationship to the brain areas historically associated with language abilities—especially Broca's area and Wernicke's area. We talk about whether the language network can be partitioned according to the subfields of linguistics, such as syntax and semantics. We discuss the power and limitations of fMRI, and the advantages of the single-subject analyses that Ev and her lab primarily use. We consider how the language network interfaces with other major neural networks—for instance, the theory of mind network and the so-called default network. And we discuss what this all tells us about the longstanding controversial claim that language is primarily for thinking rather than communicating. Along the way, Ev and I touch on: some especially interesting brains; plasticity and redundancy; the puzzle of lateralization; polyglots; aphasia; the localizer method; the decline of certain Chomskyan perspectives; the idea that brain networks are "natural kinds"; the heart of the language network; and the question of what the brain may tell us—if anything—about how language evolved. Alright friends, this is a fun one. On to my conversation with Dr. Ev Fedorenko. Enjoy! A transcript of this episode will be available soon. Notes and links 3:00 – The article by a New York Times reporter who is missing portion of her temporal lobe. The website for the Interesting Brains project. 5:30 – A recent paper from Dr. Fedorenko’s lab on the brains of three siblings, two of whom were missing portions of their brains. 13:00 – Broca’s original 1861 report. 18:00 – Many of Noam Chomsky’s ideas about the innateness of language and the centrality of syntax are covered in his book Language and Mind, among other publications. 19:30 – For an influential critique of the tradition of localizing functions in the brain, see William R. Uttal’s The New Phrenology. 23:00 – The new review paper by Dr. Fedorenko and colleagues on the language network. 26:00 – For more discussion of the different formats or modalities of language, see our earlier episode with Dr. Neil Cohn. 30:00 – A classic paper by Herbert Simon on the “architecture of complexity.” 31:00 – For one example of a naturalistic, “task-free” study that reveals the brain’s language network, see here. 33:30 – See the recent paper arguing “against cortical reorganization.” 33:00 – For more on the concept of “natural kind” in philosophy, see here. 38:00 – On the “multiple-demand network,” see a recent study by Dr. Fedorenko and colleagues. 41:00 – For a study from Dr. Fedorenko’s lab finding that syntax and semantics are distributed throughout the language network, see here. For an example of work in linguistics that does not make a tidy distinction between syntax and semantics, see here. 53:30 – See Dr. Fedorenko’s recent article on the history of individual-subject analyses in neuroscience. 1:01:00 – For an in-depth treatment of one localizer used in Dr. Fedorenko’s research, see here. 1:03:30 – A paper by Dr. Stephen Wilson and colleagues, describing recovery of language ability following stroke as a function of the location of the lesion within the language network. 1:04:20 – A paper from Dr. Fedorenko’s lab on the small language networks of polyglots. 1:09:00 – For more on the Visual Word Form Area (or VWFA), see here. For discussion of Exner’s Area, see here. 1:14:30 – For a discussion of the brain’s so-called default network, see here....