| Autor: |
Berent I; Department of Psychology, Northeastern University, Boston, MA 02115; i.berent@neu.edu., Brem AK; Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, United Kingdom; Berenson-Allen Center for Noninvasive Brain Stimulation, Beth-Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215;, Zhao X; Department of Psychology, Northeastern University, Boston, MA 02115;, Seligson E; Berenson-Allen Center for Noninvasive Brain Stimulation, Beth-Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215;, Pan H; Functional Neuroimaging Laboratory, Departments of Radiology and Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02467; and., Epstein J; Functional Neuroimaging Laboratory, Departments of Radiology and Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02467; and., Stern E; Functional Neuroimaging Laboratory, Departments of Radiology and Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02467; and., Galaburda AM; Department of Neurology, Division of Cognitive Neurology, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA 02215., Pascual-Leone A; Berenson-Allen Center for Noninvasive Brain Stimulation, Beth-Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215; Department of Neurology, Division of Cognitive Neurology, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA 02215. |
| Abstrakt: |
All spoken languages express words by sound patterns, and certain patterns (e.g., blog) are systematically preferred to others (e.g., lbog). What principles account for such preferences: does the language system encode abstract rules banning syllables like lbog, or does their dislike reflect the increased motor demands associated with speech production? More generally, we ask whether linguistic knowledge is fully embodied or whether some linguistic principles could potentially be abstract. To address this question, here we gauge the sensitivity of English speakers to the putative universal syllable hierarchy (e.g., blif ≻ bnif ≻ bdif ≻ lbif) while undergoing transcranial magnetic stimulation (TMS) over the cortical motor representation of the left orbicularis oris muscle. If syllable preferences reflect motor simulation, then worse-formed syllables (e.g., lbif) should (i) elicit more errors; (ii) engage more strongly motor brain areas; and (iii) elicit stronger effects of TMS on these motor regions. In line with the motor account, we found that repetitive TMS pulses impaired participants' global sensitivity to the number of syllables, and functional MRI confirmed that the cortical stimulation site was sensitive to the syllable hierarchy. Contrary to the motor account, however, ill-formed syllables were least likely to engage the lip sensorimotor area and they were least impaired by TMS. Results suggest that speech perception automatically triggers motor action, but this effect is not causally linked to the computation of linguistic structure. We conclude that the language and motor systems are intimately linked, yet distinct. Language is designed to optimize motor action, but its knowledge includes principles that are disembodied and potentially abstract. |
