• Research in anthropology including biological and physical, as well as cultural anthropology.
  • Sign up for PNAS eTOC alerts

Neurophysiological origin of human brain asymmetry for speech and language

  1. Anne-Lise Girauda,1
  1. aInstitut National de la Santé et de la Recherche Médicale U960-Ecole Normale Supérieure, 75005 Paris, France;
  2. bService de Neurologie, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland;
  3. cNeuroimaging Laboratory, Instituto di Ricovero e Cura a Carattere Scientifico Santa Lucia, 00179 Rome, Italy;
  4. dCentre de Neuroimagerie de Recherche, Hôpital de la Pitié-Salpêtrière, 75013 Paris, France;
  5. eInstitut National de la Santé et de la Recherche Médicale U992 Cognitive Neuroimaging Unit, Commissariat á l’Energie Atomique, NeuroSpin, 91191 Gif-sur-Yvette Cedex, France; and
  6. fDepartment of Psychology, New York University, New York, NY 10003

  1. Edited by Mortimer Mishkin, National Institute for Mental Health, Bethesda, MD, and approved September 13, 2010 (received for review June 6, 2010)

Abstract

The physiological basis of human cerebral asymmetry for language remains mysterious. We have used simultaneous physiological and anatomical measurements to investigate the issue. Concentrating on neural oscillatory activity in speech-specific frequency bands and exploring interactions between gestural (motor) and auditory-evoked activity, we find, in the absence of language-related processing, that left auditory, somatosensory, articulatory motor, and inferior parietal cortices show specific, lateralized, speech-related physiological properties. With the addition of ecologically valid audiovisual stimulation, activity in auditory cortex synchronizes with left-dominant input from the motor cortex at frequencies corresponding to syllabic, but not phonemic, speech rhythms. Our results support theories of language lateralization that posit a major role for intrinsic, hardwired perceptuomotor processing in syllabic parsing and are compatible both with the evolutionary view that speech arose from a combination of syllable-sized vocalizations and meaningful hand gestures and with developmental observations suggesting phonemic analysis is a developmentally acquired process.

Footnotes

  • 1To whom correspondence should be addressed. E-mail: anne-lise.giraud{at}ens.fr.

  • Author contributions: A.-L.G. designed research; B.M., K.L., and A.D. performed research; B.M., A.K., and A.-L.G. analyzed data; and B.M., R.S.J.F., A.K., D.P., and A.-L.G. wrote the paper.

  • The authors declare no conflict of interest.

  • This article is a PNAS Direct Submission.

  • This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1007189107/-/DCSupplemental.

Online Impact