In a group of teenagers with specific language impairment (SLI) and procedural memory impairment and a group of chronologically age-matched (CA) normal controls, the brain correlates of lexical-phonological and lexical-semantic processing concerning these expectations were investigated. Participants conducted 2 ERP measures in the auditory modality to assess lexical-semantic and lexical-phonological processing and procedural and declarative memory tasks. A statistical learning task was used to test procedural memory. A sentence judgment task modulating semantic congruency was used to examine lexical-semantic processing, while a word/nonword decision task modulating word frequency was used to assess lexical-phonological processing. The researchers looked at behavioral performance on the tasks, the mean amplitude of the cortical response, and animated topographs. The adolescents with SLI performed at random on the statistical word-learning task, although declarative memory was no different from the CA controls. The adolescents with SLI and the CA controls had similar behavioral accuracy on the lexical-semantic task. In contrast, the adolescents with SLI had significantly worse accuracy on the lexical-phonological task than the CA controls. Both groups evoked an N400 component in response to semantic congruency on the lexical-semantic test. Still, there were differences in the position and timing of the cortical reaction for the SLI and CA groups. On the lexical-phonological task, word frequency triggered an N400 component in the CA controlled but not in the adolescents with SLI. In contrast, post hoc analysis demonstrated that adolescents with SLI, but not CA controls, had a brain response depending on imageability. For the CA controls, statistical word learning was substantially linked with processing speed on the lexical judgment test, but not for the SLI adolescents. On the other hand, statistical word learning skill was unrelated to the modulation of the N400 in either task for either group. The behavioral evidence suggests that adolescents with SLI have full semantic conceptual knowledge but impaired lexical and phonological processing, consistent with the PDH. However, the pattern of cortical activation in response to semantic congruency and word frequency suggests that processing of lexical-semantic and lexical-phonological information by adolescents with a history of SLI might have been aided by both overlapping and nonoverlapping neural generators, as well as a greater reliance on declarative memory strategies, as compared to CA controls. When behavioral data and neural cortical patterns of activation were examined together, the outcomes suggested that the underlying representations of words in the lexicons of adolescents with a history of SLI might have differed qualitatively from those of their typical peers. However, these differences might have only been apparent when behavioral data and neural cortical activation patterns were examined together.
Source:jneurodevdisorders.biomedcentral.com/articles/10.1186/s11689-022-09419-z
