Dyslexia is a highly heritable neurobiological disorder defined as a persistent difficulty in learning to read. Phonological processing skills, associating letters to sounds, and word retrieval are deficient in many children with dyslexia. - Credit Lovio, Riikka
Poor reading accuracy and slow reading speed are, in turn, characteristic for adults with dyslexia.
Intact processing of even minor differences in speech sounds is essential for language development and reading skills. Speech perception requires sound discrimination and phoneme identification, despite the variation in their acoustical features.
Accurate phonological representations are also important for learning the connection between sounds and letters. Difficulties in auditory processing are common in individuals with dyslexia.
Cortical auditory processing can be investigated by recording the electroencephalography (EEG). The detection of changes in the regularities of the auditory input gives rise to neural activity in the brain that is seen as a mismatch negativity (MMN) response of the event-related potential (ERP) recorded by EEG.
As the recording of MMN requires neither a subject s behavioural response nor attention towards the sounds, it is suitable for studies of even young children.
Despite its advantages over behavioural measures, a major obstacle to the use of the MMN method has been the relatively long duration of its recording.
However, the multi-feature MMN paradigm with several types of sound changes was recently developed in order to obtain a comprehensive profile of auditory sensory memory and discrimination accuracy in a short recording time.
The present thesis investigated cortical multi-attribute auditory processing in dyslexia and the efficacy of intervention on reading-related skills and cortical speech sound discrimination.
Moreover, the feasibility of the multi-feature paradigm for dyslexia research, and studies in children was tested for the first time.
In this thesis, the multi-feature paradigm was found to be well suited for studies investigating central auditory processing in dyslexia and in children.
The results showed that cortical auditory processing is aberrant in dyslexia.
In children at risk for dyslexia, auditory processing seems to be deficient even at the initial phase of sound encoding.
Furthermore, these children also showed a widespread pattern of abnormal cortical auditory discrimination processes.
Adults with dyslexia, in turn, have difficulties in discriminating sound frequency and duration features in a complex auditory environment.
Early intervention can influence the developmental path of dyslexia, however.
The results of this thesis show that even a short intervention with audio-visual letter-sound exercises improves children s reading-related skills and cortical discrimination of vowel contrasts.
More Information:
Cortical multi-attribute auditory discrimination deficits and their amelioration in dyslexia - Lovio, Riikka
Poor reading accuracy and slow reading speed are, in turn, characteristic for adults with dyslexia.
Intact processing of even minor differences in speech sounds is essential for language development and reading skills. Speech perception requires sound discrimination and phoneme identification, despite the variation in their acoustical features.
Accurate phonological representations are also important for learning the connection between sounds and letters. Difficulties in auditory processing are common in individuals with dyslexia.
Cortical auditory processing can be investigated by recording the electroencephalography (EEG). The detection of changes in the regularities of the auditory input gives rise to neural activity in the brain that is seen as a mismatch negativity (MMN) response of the event-related potential (ERP) recorded by EEG.
As the recording of MMN requires neither a subject s behavioural response nor attention towards the sounds, it is suitable for studies of even young children.
Despite its advantages over behavioural measures, a major obstacle to the use of the MMN method has been the relatively long duration of its recording.
However, the multi-feature MMN paradigm with several types of sound changes was recently developed in order to obtain a comprehensive profile of auditory sensory memory and discrimination accuracy in a short recording time.
The present thesis investigated cortical multi-attribute auditory processing in dyslexia and the efficacy of intervention on reading-related skills and cortical speech sound discrimination.
Moreover, the feasibility of the multi-feature paradigm for dyslexia research, and studies in children was tested for the first time.
In this thesis, the multi-feature paradigm was found to be well suited for studies investigating central auditory processing in dyslexia and in children.
The results showed that cortical auditory processing is aberrant in dyslexia.
In children at risk for dyslexia, auditory processing seems to be deficient even at the initial phase of sound encoding.
Furthermore, these children also showed a widespread pattern of abnormal cortical auditory discrimination processes.
Adults with dyslexia, in turn, have difficulties in discriminating sound frequency and duration features in a complex auditory environment.
Early intervention can influence the developmental path of dyslexia, however.
The results of this thesis show that even a short intervention with audio-visual letter-sound exercises improves children s reading-related skills and cortical discrimination of vowel contrasts.
More Information:
Cortical multi-attribute auditory discrimination deficits and their amelioration in dyslexia - Lovio, Riikka
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