Effects of time-compressed speech training on multiple functional and structural neural mechanisms involving the left superior temporal gyrus

Time-compressed speech is an artificial form of rapidly presented speech. Training with time compressed speech in a second language leads to adaptation toward time-compressed speech in a second language and toward time compressed speech in different languages. However, the effects of training with time-compressed speech of a second language (TCSSL) on diverse cognitive functions and neural mechanisms beyond time compressed speech-related activation are unknown. We investigated the effects of 4 weeks of training with TCSSL on the fractional amplitude of spontaneous low-frequency fluctuations (fALFF) of 0.01–0.08 Hz, resting-state functional connectivity (RSFC) with the left superior temporal gyrus (STG), fractional anisotropy (FA), and regional gray matter volume (rGMV) of young adults by magnetic resonance imaging. There were no significant differences in change of performance of measures of cognitive functions or second language skills after training with TCSSL compared with that of the active control group. However, compared with the active control group, training with TCSSL was associated with increased fALFF, RSFC, and FA and decreased rGMV involving areas in the left STG. These results lacked evidence of a far transfer effect of time compressed speech training on a wide range of cognitive functions and second language skills in young adults. However, these results demonstrated effects of time compressed speech training on gray and white matter structures as well as on resting-state intrinsic activity and connectivity involving the left STG, which plays a key role in listening comprehension.