Cortical competition during language discrimination

How do human listeners differentiate one language from another? In this study we examine the contributions of acoustic and linguistic cues to successful language discrimination. In particular, we report findings that reveal patterns of cortical competition as a function of the competition between prosodic, phonological, and lexical semantic information during language discrimination. We manipulated four types of stimuli in the listening environment: synthesized speech with rhythmic information, synthesized speech with rhythmic plus intonational information, natural speech from Japanese and Italian, and natural speech from Chinese and English. Our study shows that, depending on the amount and the kind of cues available, the listener recruits different areas of the brain for the same language task. Furthermore, brain activations do not monotonically multiply as a function of the complexity of the cues available, but are the outcomes of cue competition as a function of cue validity for the discrimination task. These findings show how acoustic and linguistic cues lead to cortical competition and how cortical activities adapt to the task demand for successful information processing.