THE EFFECT OF PERIODICITY AND "VOWELNESS" OF A SOUND ON CORTICAL AUDITORY RESPONSES IN CHILDREN

• The neural basis of speech decoding is of both fundamental and practical interest for many areas of neuroscience. The discovery of highly specialized areas of the temporal cortex, which perform acoustic analysis of vowels and the pitch of spectrally complex periodic sounds, opens the way for new directions in research on speech signal processing in healthy and diseased brain. Here, we sought to dissect the effects of periodicity and "vowelness" of a sound on the neural response of the auditory cortex in typically developing children aged 7-12 years. We hypothesized that although both of these properties are pertinent to speech vowels, their processing occurs at different levels of cortical ventral auditory stream. To test this hypothesis, we constructed a set of acoustic stimuli, manipulating their periodicity and 'vowelness' separately, and used magnetoencephalography in combination with individual brain models to assess the cortical topography and temporal dynamic of cortical sources, which respond selectively to either sounds' periodicity or to their 'vowelness'. We found that the early auditory responses (50-150 ms) were highly sensitive to both periodicity and 'vowelness' of a sound, although they were separable from each other in terms of response timing, source localization and hemispheric asymmetry. Our findings suggest that the separate neural networks are independently tuned for each of these properties of the speech sound, and that transformation of the respective acoustic properties into a speech feature take place at these earliest stages in the speech processing hierarchy. Our results may help to evaluate the role of specific neural deficits in the processing of low-level properties of speech sounds in language disorders.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Neurovetenskaper (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Neurosciences (hsv//eng)

Nyckelord

auditory evoked responses

children

MEG

periodicity and voweless of sounds

sustained field

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)