RESUMO
INTRODUCTION: Developmental dyslexia (DD) is a frequent language-based learning disorder. The predominant etiological view postulates that reading problems originate from a phonological impairment. METHOD: We studied mismatch negativity (MMN) and Late Discriminative Negativity (LDN) to syllables change in both children (n=12; 8-12 years) and young adults (n=15; 14-23 years) with DD compared with controls. RESULTS/DISCUSSION: The present study confirmed abnormal automatic discrimination of syllable changes in both children and adults with developmental dyslexia. MMN topographic, amplitude and latency group differences were evidenced, suggesting different brain mechanisms involved in elementary auditory stimulus change-detection in DD, especially in the left hemisphere. The LDN results demonstrated that the auditory disorder of temporal processing in DD children becomes more serious at late stages of information processing and that the apparent cerebral hypo reactivity to speech changes in DD actually may correspond to additional processes. The age-related differences observed in both MMN and LDN topographies, amplitudes and latency between subjects with DD and controls could indicate different developmental courses in the neural representation of basic speech sounds in good and poor readers, with a tendency to normalization with increasing age. CONCLUSION: Our results showing atypical electrophysiological concomitants of speech auditory perception in DD strongly support the hypothesis of deviant cortical organization in DD.
Assuntos
Percepção Auditiva , Transtornos da Percepção Auditiva/fisiopatologia , Discriminação Psicológica , Dislexia/fisiopatologia , Potenciais Evocados Auditivos , Percepção da Fala , Adolescente , Fatores Etários , Análise de Variância , Transtornos da Percepção Auditiva/diagnóstico , Transtornos da Percepção Auditiva/psicologia , Estudos de Casos e Controles , Criança , Dislexia/diagnóstico , Dislexia/psicologia , Eletroencefalografia , Eletrofisiologia , Feminino , Humanos , Masculino , Adulto JovemRESUMO
We report the case of a young girl who presented severe learning disabilities in oral and written language related to a continuous spike-waves during slow sleep (CSWS) syndrome. A sleep EEG recording obtained in her younger brother, who presented a clinical pattern suggesting developmental dysphasia, also showed a CSWS syndrome. These two clinical cases underscore the need to look for this syndrome in the siblings of an affected child when learning difficulties appear in a child who previously had normal psychomotor development.