Neural correlates of switching from auditory to speech perception. Dehaene-Lambertz, G., Pallier, C., Serniclaes, W., Sprenger-Charolles, L., Jobert, A., & Dehaene, S. Neuroimage, 24(1):21-33, 2005.
doi  abstract   bibtex   
Many people exposed to sinewave analogues of speech first report hearing them as electronic glissando and, later, when they switch into a 'speech mode', hearing them as syllables. This perceptual switch modifies their discrimination abilities, enhancing perception of differences that cross phonemic boundaries while diminishing perception of differences within phonemic categories. Using high-density evoked potentials and fMRI in a discrimination paradigm, we studied the changes in brain activity that are related to this change in perception. With ERPs, we observed that phonemic coding is faster than acoustic coding: The electrophysiological mismatch response (MMR) occurred earlier for a phonemic change than for an equivalent acoustic change. The MMR topography was also more asymmetric for a phonemic change than for an acoustic change. In fMRI, activations were also significantly asymmetric, favoring the left hemisphere in both perception modes. Furthermore, switching to the speech mode significantly enhanced activation in the posterior parts of the left superior gyrus and sulcus relative to the non-speech mode. When responses to a change of stimulus were studied, a cluster of voxels in the supramarginal gyrus was activated significantly more by a phonemic change than by an acoustic change. These results demonstrate that phoneme perception in adults relies on a specific and highly efficient left-hemispheric network, which can be activated in top-down fashion when processing ambiguous speech/non-speech stimuli.
@Article{Dehaene-Lambertz2005,
  author   = {Ghislaine Dehaene-Lambertz and Christophe Pallier and Willy Serniclaes and Liliane Sprenger-Charolles and Antoinette Jobert and Stanislas Dehaene},
  journal  = {Neuroimage},
  title    = {Neural correlates of switching from auditory to speech perception.},
  year     = {2005},
  number   = {1},
  pages    = {21-33},
  volume   = {24},
  abstract = {Many people exposed to sinewave analogues of speech first report hearing
	them as electronic glissando and, later, when they switch into a
	'speech mode', hearing them as syllables. This perceptual switch
	modifies their discrimination abilities, enhancing perception of
	differences that cross phonemic boundaries while diminishing perception
	of differences within phonemic categories. Using high-density evoked
	potentials and fMRI in a discrimination paradigm, we studied the
	changes in brain activity that are related to this change in perception.
	With ERPs, we observed that phonemic coding is faster than acoustic
	coding: The electrophysiological mismatch response (MMR) occurred
	earlier for a phonemic change than for an equivalent acoustic change.
	The MMR topography was also more asymmetric for a phonemic change
	than for an acoustic change. In fMRI, activations were also significantly
	asymmetric, favoring the left hemisphere in both perception modes.
	Furthermore, switching to the speech mode significantly enhanced
	activation in the posterior parts of the left superior gyrus and
	sulcus relative to the non-speech mode. When responses to a change
	of stimulus were studied, a cluster of voxels in the supramarginal
	gyrus was activated significantly more by a phonemic change than
	by an acoustic change. These results demonstrate that phoneme perception
	in adults relies on a specific and highly efficient left-hemispheric
	network, which can be activated in top-down fashion when processing
	ambiguous speech/non-speech stimuli.},
  doi      = {10.1016/j.neuroimage.2004.09.039},
  keywords = {Adult, Attention, Auditory, Auditory Pathways, Auditory Perception, Brain, Brain Mapping, Cerebral, Computer-Assisted, Dominance, Evoked Potentials, Female, Humans, Image Processing, Magnetic Resonance Imaging, Male, Phonetics, Reference Values, Speech Perception, 15588593},
}

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