News and views on the neural organization of language moderated by Greg Hickok and David Poeppel
moderated by Greg Hickok and David Poeppel
Hi Greg, Thanks for this nice X-ray movie. But, at the brain level, I do not see any evidence that 'implicitly, nonspeech and speech movements have separate neural mechanisms, and the practice of one does not facilitate the function of the other'. I of course do not disagree about distinct neural substrates of speech vs. nonspeech motor control. But, as you probably know, there is also a lot of evidence for shared neural mechanisms (Ackerman, Brown, Cheng, Riecker, Simonyan, Terumitsu, Wise… and others). As a clear example, one of my colleagues, Krystyna Grabski, recently performed an fMRI experiment providing evidence for a core neural network involved in laryngeal and supralaryngeal speech and nonspeech motor control in healthy adults. Best,MarcGrabski, K., Lamalle, L., Vilain, C., Schwartz, J.-L, Vallée, N. Troprès, I., Baciu, M. Le Bas, J.-F & Sato, M. (2012). Functional MRI assessment of orofacial articulators: neural correlates of lip, jaw, larynx and tongue movements. Human Brain Mapping, 33(10): 2306-2321.
Greg,It seems to me that “Marc’s” first two sentences are saying the same thing.First sentence,“But, at the brain level, I do not see any evidence that “implicitly, nonspeech and speech movements have separate neural mechanisms.””Second sentence,“I of course do not disagree about distinct neural substrates of speech vs. nonspeech motor control.” Bold italics are not in the original.In addition, I didn’t say anything about shared neural mechanisms in my post. But, I don’t think they are shared. I believe, through evolution, we have developed specialized neural circuits to subserve specialized behaviors. I suggest speech production is a specialized behavior as evidenced in the x-ray movie. The girl struggled to put the tongue behind the alveolar ridge, and failed overall. In the [da] sequence, she clearly and rapidly made the necessary tongue-tip-alveolar ridge contact.Maybe I misinterpreted what Marc was saying.Ron
Hi Ron,Thanks for your post. My only point was that I do not disagree (in fact, I fully agree with you) but, 'stricly speaking', I do not see any evidence on the X-ray movie for 'separate neural mechanisms'. About specialized non-speech and speech orofacial behaviors, I think everyone agree on that point. For speech production viewed as a 'specialized behavior', there are a number of data and theories (e.g., Frame/Content theory by MacNeilage and Davis, exaptation mechanisms on feeding to speaking, etc).But my point remains. We need more data to understand the above-mentioned possibility of 'separate neural mechanisms'.Marc SatoPS: one intesting recent paper from my colleagues:Serrurier,Badin, Barney, Boë & Savariaux (2012). The tongue in speech and feeding: Comparative articulatory modelling. Journal of Phonetics 40, 6 (2012) 745-763
Maybe you both could clarify what you mean by "separate neural mechanisms"?
I might define 'separate neural mechanisms' as "the neuroglia and neurons that subserve a particular function." In the present case, speech production.Ron Netsell
Hi Ron,Sorry for this debate. It is a never ending story (as Greg would say, could you clarify what you mean by "particular function"?).In your post, you argue from the x-ray movies that "this represents a clear dissociation of tongue control for nonspeech and speech movements". But from X-ray movie, it is difficult to speak about 'separate neural mechanisms'.I do think that some neuroglia and neurons both subserve orofacial speech and nonspeech (tongue) motor control. I also think that some are involved in specific motor movements, kynematics, action goals, etc...So I think we both agree and we are speaking on the wind and weather.Marc
Hello Marc,Speaking of neuroglia and neurons, "...some are involved in specific motor movements."Yes, I think we are in agreement.Thanks for the dialog.Ron
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