Semantic Cortical Activation in Dyslexic Readers

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Helenius, Päivi
dc.contributor.author Salmelin, Riitta
dc.contributor.author Service, Elisabet
dc.contributor.author Connolly, John F.
dc.date.accessioned 2015-05-18T09:01:04Z
dc.date.available 2015-05-18T09:01:04Z
dc.date.issued 1999
dc.identifier.citation Helenius, Päivi & Salmelin, Riitta & Service, Elisabet & Connolly, John F. 1999. Semantic Cortical Activation in Dyslexic Readers. Journal of Cognitive Neuroscience. Volume 11, Issue 5. P. 535-550. ISSN 0898-929X (printed). DOI: 10.1162/089892999563599. en
dc.identifier.issn 0898-929X (printed)
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/16070
dc.description.abstract The combined temporal and spatial resolution of MEG (magnetoencephalography) was used to study whether the same brain areas are similarly engaged in reading comprehension in normal and developmentally dyslexic adults. To extract a semantically sensitive stage of brain activation we manipulated the appropriateness of sentence-ending words to the preceding sentence context. Sentences, presented visually one word at a time, either ended with a word that was (1) expected, (2) semantically appropriate but unexpected, (3) semantically anomalous but sharing the initial letters with the expected word, or (4) both semantically and orthographically inappropriate to the sentence context. In both subject groups all but the highly expected sentence endings evoked strong cortical responses, localized most consistently in the left superior temporal cortex, although additional sources were occasionally found in more posterior parietal and temporal areas and in the right hemisphere. Thus, no significant differences were found in the spatial distribution of brain areas involved in semantic processing between fluent and dyslexic readers. However, both timing and strength of activation clearly differed between the two groups. First, activation sensitivity to word meaning within a sentence context began about 100 msec later in dyslexic than in control subjects. This is likely to result from affected presemantic processing stages in dyslexic readers. Second, the neural responses were significantly weaker in dyslexic than in control subjects, indicating involvement of a smaller or less-synchronous neural population in reading comprehension. Third, in contrast to control subjects, the dyslexic readers showed significantly weaker activation to semantically inappropriate words that began with the same letters as the most expected word than to both orthographically and semantically inappropriate sentence-ending words. Thus, word recognition by the dyslexic group seemed to be qualitatively different: Whereas control subjects perceived words as wholes, dyslexic subjects may have relied on sublexical word recognition and occasionally mistook a correctly beginning word for the one they had expected. en
dc.format.extent 535-550
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher MIT Press en
dc.relation.ispartofseries Journal of Cognitive Neuroscience en
dc.relation.ispartofseries Volume 11, Issue 5
dc.rights © 1999 MIT Press. This is the final version of the article: Helenius, Päivi ; Salmelin, Riitta ; Service, Elisabet ; Connolly, John F. 1999. Semantic Cortical Activation in Dyslexic Readers. Journal of Cognitive Neuroscience. Volume 11, Issue 5. P. 535-550. ISSN 0898-929X (printed). DOI: 10.1162/089892999563599, which has been published in final form at http://www.mitpressjournals.org/doi/abs/10.1162/089892999563599#.VVmnc2OkuSo en
dc.subject.other Linguistics en
dc.subject.other Medical sciences en
dc.title Semantic Cortical Activation in Dyslexic Readers en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.rights.holder MIT Press
dc.contributor.school Perustieteiden korkeakoulu fi
dc.contributor.school School of Science en
dc.contributor.department Neurotieteen ja lääketieteellisen tekniikan laitos fi
dc.contributor.department Department of Neuroscience and Biomedical Engineering en
dc.subject.keyword dyslexia en
dc.subject.keyword cortical activity en
dc.subject.keyword magnetoencephalography en
dc.identifier.urn URN:NBN:fi:aalto-201505182713
dc.type.dcmitype text en
dc.identifier.doi 10.1162/089892999563599
dc.type.version Final published version en


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