Development of fMRI tests for children with central auditory processing disorders

The term 'central auditory processing disorder' (CAPD; in German-speaking countries: 'auditive Verarbeitungs- und Wahrnehmungsstörung', AVWS) embraces various complex disorders of central auditory function. The purpose of this preliminary study was to develop a functional magnetic resonance imaging (fMRI) test set in order to extend the diagnostic work-up to include imaging, and thus to improve both diagnostic performance and the monitoring of treatment outcome. fMRI was performed in 11 healthy children ranging in age from 7 to 10 years and in 11 healthy adults (age range: 23 to 31 years). Three tests, used for diagnosis of CAPD, served as the basis for fMRI paradigms: the Hannover phoneme discrimination test (HPDT); the auditory memory span test (MST) and the dichotic listening test (DLT). In the HPDT, activations in the dorsal part of the superior temporal gyrus (STG) were found on both sides, in the Broca area and in the left middle temporal gyrus, typical for phonemic tasks. The MST showed bilateral activations of the STG, typical for processing of pseudo-words. In addition, bilateral activation of the hippocampus was found. However, there was no clear activity in the left supramarginal gyrus, where the phonological store is thought to be located. The DLT showed activations of the bilateral STG and of the left inferior frontal gyrus. Predominantly, the paradigms showed typical activation patterns of the examined central auditory functions. These results can serve as a reference for future examinations in children with AVWS/CAPD.