The Relationship of Language and Intelligence Development to the Maturity of the Subcortical Structures in Children with Specific Language Disorders
Objective. To detect possible dysfunctions of subcortical brain structures in children with severe disorders of language development and to study the association of such dysfunctions with linguistic and cognitive development, particularly the development of nonverbal intelligence on the level of the norm.
Design. 45 children with severe speech disorders, aged 4 to 7 years, took part in the study: 9 girls and 36 boys who were patients at the Prognoz neurological clinic for children (Saint Petersburg). The diagnoses according to ICD-10 were the following: F.80.1 – expressive speech disorder – 35 children; F.80.2 – receptive speech disorder – 10 children. The functional state of the brain stem was assessed by the auditory brain stem response (ABR) method. A modified stimulus was used to register peak VI, that is, a short tone burst with a frequency of 4,000 Hz, plateau duration of 0.5 ms, initial front of 0.5 ms, and intensity of 70 dB above the hearing threshold.
Results. Analysis of the evoked potentials gave the following results: Deceleration of vestibular and/or auditory information conduction on the level of brain stem structures was detected in 98% of the children. Deceleration of vestibular information conduction was manifested in increased latency of the positive wave P13 cVEMP in comparison with the normative value. Deceleration of auditory information conduction was shown in an increase of the peak intervals of ABRs in comparison with normative values.
Conclusions. All the children displayed conduction disturbances in the auditory and vestibular systems. Conduction disturbances in the auditory system were directly connected with the severity of their speech problems. Conduction disturbances in the vestibular system were associated with lower nonverbal intelligence.
Keywords: cognitive processes, language, subcortical structures of the brain, children, severe disorders of language development.