Browsing by Subject "sanojen hermostollinen muistiedustuma"

Specific Language Impairment is a broad spectrum disorder of language development, not including deficits of non-verbal intelligence. It typically manifests in a slower rate of learning new words. According to previous research, the disorder is connected with anomalous lateralization of speech related neural processes. The neural basis of Specific Language Impairment has mainly been studied in adults and school aged children, even though the disorder manifests already in preschool age. Studying the neural representations of words and their changes during a learning process in preschool children can help to recognize the cognitive risk factors of Specific Language Impairment. This study aims to confirm, whether neural representations of words are anomalously lateralized in Specific Language Impairment. In addition, differences in the rate of formation of the neural representation of words between children with Specific Language Impairment and children with typically developed language skills are studied. 12 children with Specific Language Impairment and 12 children with typically developed linguistic abilities between the ages 3 to 6 participated in the study. The differences between groups in event related potentials for a known word and an unknown pseudoword and the changes they undergo during passive listening were explored. It was found that the evoked response potentials for both stimulus types were more clearly lateralized on the left side in linguistically typically developed children than in those with Specific Language Impairment, suggesting atypical organization of word representations. Group differences were also found in the event related potentials elicited by the pseudoword: in the control group the event related potential for the pseudoword differed significantly from the one for the known word in the beginning of the experiment (lexicality effect) and resembled it by the end of the experiment (lexicalization), whereas no such difference in the beginning of and change during the experiment was observed in the experimental group. Based on this study Specific Language Impairment is associated with anomalous neural functions both in the automatic activation of the neural representations of words and in the formation of new word representations during passive listening. Both of these phenomena may be related to abnormal language development, but the mechanisms should be determined in more detail in further investigations.