Dialectal differences in hemispheric specialization for Japanese lexical pitch accent

Area of Science:

• Neuroscience
• Linguistics
• Psychology

Background:

• Language experience influences perceptual abilities and neural specialization.
• Lexical pitch accent systems in languages like Japanese utilize pitch for word meaning.
• The effect of dialectal pitch differences on neural processing remains under-investigated.

Purpose of the Study:

• To investigate if dialectal variations in lexical pitch usage affect functional lateralization for pitch processing.
• To compare brain responses to pitch changes in speakers of Standard Japanese versus speakers of 'accentless' dialects.

Main Methods:

• Functional hemodynamic responses were measured using neuroimaging techniques.
• Participants included native speakers of Standard (Tokyo) Japanese and native speakers of Japanese dialects lacking lexical pitch accent.
• Stimuli included pitch pattern changes within words and within harmonic-complex tones.

Main Results:

• Standard Japanese speakers exhibited left-dominant temporal region responses to pitch pattern changes within words.
• Speakers of 'accentless' dialects did not display this left-dominance for within-word pitch changes.
• Brain activation patterns for pitch changes in non-linguistic sounds also differed between the two groups.

Conclusions:

• Neural processing of pitch information is influenced by the listener's native dialect.
• Linguistic experience, even with non-linguistic sounds, can shape pitch processing pathways.
• This suggests a broader impact of language on auditory perception and neural specialization.