Information transmission defect identified and localized in language learning impaired children by means of electrophysiology.

Children with language processing deficits have various learning impairments and poor scholastic performance. In 3-10% of all children a specific language processing deficit can be identified by the Sound Connecting Sub-Test of the Illinois Test of Psycholinguistic-Abilities (SC-ITPA). These children among which we drew our index group (AS-Group) suffer from the disability to recognize isolated sounds as parts of words. Following linguistic terminology this is known as an auditory sequential sound processing deficit (ASSPD) Eighteen children (AS-Group) and 21 controls (C-Group) were subjected to mapped P300 evoked potential analyses of cortical response to acoustic stimulation in the oddball paradigm. The data presented here show that there exists significant relation between the P300 amplitude reduction and ASSPD. The P300 amplitude decrease measured in the AS-Group is due to a reduced information transmission in accordance with Johnson's Triarchic Model of the P300 Amplitude. The cerebral structures involved in poor language processing are localized at the left temporo-parietal cortex. This supports the hypothesis that the underlying neuronal defect of ASSPD is localized in the language center and not in the auditory pathway. The P300 amplitude may serve as electrophysiological tool to identify ASSPD and to quantify the degree of improvement in the course of specific therapy.