We performed a resting-state functional connectivity study to investigate directly the functional correlations within the perisylvian language networks by seeding from 3 subregions of Broca's complex (pars opercularis, pars triangularis, and pars orbitalis) and their right hemisphere homologues. A clear topographical functional connectivity pattern in the left middle frontal, parietal, and temporal areas was revealed for the 3 left seeds. This is the first demonstration that a functional connectivity topology can be observed in the perisylvian language networks. The results support the assumption of the functional division for phonology, syntax, and semantics of Broca's complex as proposed by the memory, unification, and control (MUC) model and indicated a topographical functional organization in the perisylvian language networks, which suggests a possible division of labor for phonological, syntactic, and semantic function in the left frontal, parietal, and temporal areas.

In this article, we report the results of a study on the relationship between individual differences in language learning aptitude and the structural connectivity of language pathways in the adult brain, the first of its kind. We measured four components of language aptitude (vocabulary learning; sound recognition; sound-symbol correspondence; and grammatical inferencing) using the LLAMA language aptitude test. Spatial working memory, verbal working memory and IQ were also measured as control factors. Language Aptitude and Language Pathways in the BrainDiffusion Tensor Imaging was employed to investigate the structural connectivity of language pathways in the perisylvian language network. Regression analysis suggested significant correlations between most of these behavioural measures and the structural connectivity of certain language pathways, that is, grammatical inferencing and the BA45-and BA46-Temporal pathway, sound-symbol correspondence and the interhemispheric BA45 pathway, vocabulary learning and the BA47-Parietal pathway, IQ and the BA44-and BA-47Parietal pathways, the BA47-Temporal pathway and interhemispheric BA45 pathway, spatial working memory and the interhemispheric BA6 pathway and the BA47-Parietal pathway, and verbal working memory and the BA47-Temporal pathway. These findings provide further insights into the neural underpinnings of the variation in language aptitude of human adults and are discussed in relation to relevant findings in the literature.

We investigated, using functional magnetic resonance imaging (fMRI), whether semantic discrimination, an inner linguistic task without overt articulation, can elicit activation in the cerebellum. Six subjects performed three semantic tasks with different loads of discrimination while being scanned. All three semantic tasks activated distributed brain areas, including the right posterior inferior cerebellum. Much stronger activation was found in the cerebellum in more difficult tasks, in terms of the activation volume and signal intensity. These results suggest that the cerebellum activation is involved in semantic discrimination and is modulated by discrimination difficulty.

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Diffusion tensor imaging (DTI) and a longitudinal language learning approach were applied to investigate the relationship between the achieved second language (L2) proficiency during L2 learning and the reorganization of structural connectivity between core language areas. Language proficiency tests and DTI scans were obtained from German students before and after they completed an intensive 6-week course of the Dutch language. In the initial learning stage, with increasing L2 proficiency, the hemispheric dominance of the Brodmann area (BA) 6-temporal pathway (mainly along the arcuate fasciculus) shifted from the left to the right hemisphere. With further increased proficiency, however, lateralization dominance was again found in the left BA6-temporal pathway. This result is consistent with reports in the literature that imply a stronger involvement of the right hemisphere in L2 processing especially for less proficient L2 speakers. This is the first time that an L2 proficiency-dependent laterality shift in the structural connectivity of language pathways during L2 acquisition has been observed to shift from left to right and back to left hemisphere dominance with increasing L2 proficiency. The authors additionally find that changes in fractional anisotropy values after the course are related to the time elapsed between the two scans. The results suggest that structural connectivity in (at least part of) the perisylvian language network may be subject to fast dynamic changes following language learning.