Neural Attunement Processes in Infants during the Acquisition of a Language-Specific Phonemic Contrast

Abstract

To elucidate the developmental neural attunement process in the language-specific phonemic repertoire, cerebral hemodynamic responses to a Japanese durational vowel contrast were measured in Japanese infants using near-infrared spectroscopy. Because only relative durational information distinguishes this particular vowel contrast, both first and second language learners have difficulties in acquiring this phonemically crucial durational difference. Previous cross-linguistic studies conducted on adults showed that phonemespecific, left-dominant neural responses were observed only for native Japanese listeners. Using the same stimuli, we show that a larger response to the across-category changes than to the within-category changes occurred transiently in the 6-to 7-month-old group before stabilizing in the groups older than 12 months. However, the left dominance of the phoneme-specific response in the auditory area was observed only in the groups of 13 months and above. Thus, the durational phonemic contrast is most likely processed first by a generic auditory circuit at 6 -7 months as a result of early auditory experience. The neural processing of the contrast is then switched over to a more linguistic circuit after 12 months, this time with a left dominance similar to native adult listeners.

The hemodynamic response to acoustically modified syllables in premature and full term newborn infants acquired by near infrared spectroscopy.

“…The increase in the [oxyHb] response and the decrease of the [deoxyHb] response in both groups and both conditions (see figure 4) corresponds to the wellknown vascular response dynamics in newborns (Peña et al, 2003;Minagawa-Kawai, Mori, Naoi, & Kojima, 2007;Gervain, Macagno, Cogoi, Peña, & Mehler, 2008;Telkemeyer, Rossi, Koch, Nierhaus, Steinbrink, Poeppel, et al, 2009). ), and in older infants (Cannestra, Wartenburger, Obrig, Villringer, & Toga, 2003;Taga, Asakawa, Hirasawa, & Konishi, 2003).…”

Development of Hemispheric Specialization for Lexical Pitch–Accent in Japanese Infants

“…Stronger left-side activation for a Japanese vowel duration contrast was seen after 13 months of age, whereas bilateral activation was found with younger infants (Minagawa-Kawai, Mori, Naoi, & Kojima, 2007). However, the lack of behavioral data makes it difficult to interpret the results of this study.…”

“…NIRS measures relative changes in the concentration of hemoglobin (Hb) noninvasively in localized brain tissues without the loud noises that are associated with MRI. It requires minimum constraints on participants and is therefore well suited for studying infants (Minagawa-Kawai et al, 2007;Homae et al, 2006;Peña et al, 2003).…”

Spatiotemporal properties of cortical haemodynamic response to auditory stimuli in sleeping infants revealed by multi-channel near-infrared spectroscopy

“…Studies comparing cortical response to the same stimulation between different age groups have shown developmental changes in activation patterns over months [25,57,59,64]. This approach sometimes reveals developmental changes that are beyond expectation based on hypothesis-driven neuroimaging.…”