Neural signatures of second language proficiency in narrative processing

Neural Correlates of Narrative Reading Development: A Comparative fMRI Study of Adults and Children Using Time-Locked Inter-Subject Correlation Analyses

The naturalistic paradigm and analytical methods present new approaches that are particularly suitable for research concentrating on narrative reading development. We analyzed fMRI data from 44 adults and 42 children engaged in story reading using time-locked inter-subject correlation (ISC), inter-subject representation similarity analysis (IS-RSA), and inter-subject functional correlation (ISFC). The ISC results indicated that for both children and adults, narrative reading recruited not only traditional reading areas but also regions that are sensitive to long-time-scale information, such as the medial prefrontal cortex and hippocampus, which increased involvement from children to adults. The results of the IS-RSA indicated that during narrative reading, children exhibited greater uniqueness in neural patterns, while adults demonstrated greater similarity. The analysis of reading-level subgroups with the ISC and ISFC reveals differences in narrative reading development that span from children to adults, especially for regions sensitive to long-time-scale semantic processing. These results indicate that the maturity and experience play a crucial role in narrative reading development.

Attention-Driven Modulation of Auditory Cortex Activity during Selective Listening in a Multispeaker Setting

Real-world listening settings often consist of multiple concurrent sound streams. To limit perceptual interference during selective listening, the auditory system segregates and filters the relevant sensory input. Previous work provided evidence that the auditory cortex is critically involved in this process and selectively gates attended input toward subsequent processing stages. We studied at which level of auditory cortex processing this filtering of attended information occurs using functional magnetic resonance imaging (fMRI) and a naturalistic selective listening task. Forty-five human listeners (of either sex) attended to one of two continuous speech streams, presented either concurrently or in isolation. Functional data were analyzed using an inter-subject analysis to assess stimulus-specific components of ongoing auditory cortex activity. Our results suggest that stimulus-related activity in the primary auditory cortex and the adjacent planum temporale are hardly affected by attention, whereas brain responses at higher stages of the auditory cortex processing hierarchy become progressively more selective for the attended input. Consistent with these findings, a complementary analysis of stimulus-driven functional connectivity further demonstrated that information on the to-be-ignored speech stream is shared between the primary auditory cortex and the planum temporale but largely fails to reach higher processing stages. Our findings suggest that the neural processing of ignored speech cannot be effectively suppressed at the level of early cortical processing of acoustic features but is gradually attenuated once the competing speech streams are fully segregated.