Diffusion Tensor Imaging Reveals White Matter Microstructure Correlations With Auditory Processing Ability

Department of Radiology, Pediatric Neuroimaging Research Consortium, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.
Ear and hearing (Impact Factor: 2.84). 11/2010; 32(2):156-67. DOI: 10.1097/AUD.0b013e3181f7a481
Source: PubMed


Correlation of white matter microstructure with various cognitive processing tasks and with overall intelligence has been previously demonstrated. We investigate the correlation of white matter microstructure with various higher-order auditory processing tasks, including interpretation of speech-in-noise, recognition of low-pass frequency filtered words, and interpretation of time-compressed sentences at two different values of compression. These tests are typically used to diagnose auditory processing disorder (APD) in children. Our hypothesis is that correlations between white matter microstructure in tracts connecting the temporal, frontal, and parietal lobes, as well as callosal pathways, will be seen. Previous functional imaging studies have shown correlations between activation in temporal, frontal, and parietal regions from higher-order auditory processing tasks. In addition, we hypothesize that the regions displaying correlations will vary according to the task because each task uses a different set of skills.
Diffusion tensor imaging (DTI) data were acquired from a cohort of 17 normal-hearing children aged 9 to 11 yrs. Fractional anisotropy (FA), a measure of white matter fiber tract integrity and organization, was computed and correlated on a voxelwise basis with performance on the auditory processing tasks, controlling for age, sex, and full-scale IQ.
Divergent correlations of white matter FA depending on the particular auditory processing task were found. Positive correlations were found between FA and speech-in-noise in white matter adjoining prefrontal areas and between FA and filtered words in the corpus callosum. Regions exhibiting correlations with time-compressed sentences varied depending on the degree of compression: the greater degree of compression (with the greatest difficulty) resulted in correlations in white matter adjoining prefrontal (dorsal and ventral), whereas the smaller degree of compression (with less difficulty) resulted in correlations in white matter adjoining audiovisual association areas and the posterior cingulate. Only the time-compressed sentences with the lowest degree of compression resulted in positive correlations in the centrum semiovale; all the other tasks resulted in negative correlations.
The dependence of performance on higher-order auditory processing tasks on brain anatomical connectivity was seen in normal-hearing children aged 9 to 11 yrs. Results support a previously hypothesized dual-stream (dorsal and ventral) model of auditory processing, and that higher-order processing tasks rely less on the dorsal stream related to articulatory networks and more on the ventral stream related to semantic comprehension. Results also show that the regions correlating with auditory processing vary according to the specific task, indicating that the neurological bases for the various tests used to diagnose APD in children may be partially independent.

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    • "Furthermore, behavioral tests most frequently utilized in the diagnosis of APD have been repeatedly criticized for relying on higher order processing constructs, including memory, language, and attention (Cacace and McFarland 2005, 2013; Moore 2006; Moore et al. 2010). A recent diffusion tensor imaging (DTI) study investigating the neural correlates of several behavioral tests used in the diagnosis of APD (Schmithorst et al. 2011), corroborated this concern by demonstrating that test performance correlated with independent white matter integrity in regions subserving higher order processing constructs. These findings cast doubt on the interpretation of abnormal behavioral task performance as indicative of pure sensory APD, since supramodal neural deficits may alternatively account for deficient performance. "
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    • "It must be expected, thus, that the visual system encompasses – to some extent – preconfigurated connections with the auditory system providing a basis for interactions between the two modalities. Indeed, a recent Diffusion Tensor Imaging study (DTI) – evaluating white matter parameters in children – found inter-subject differences in fractional anisotropy to correlate with the comprehension of time-compressed speech [73]: Moderately manipulated signals (40% compression) yielded these effects in white matter areas adjacent to audiovisual association cortex and posterior cingulate gyrus while a greater degree of compression resulted in changes of tracts adjoining prefrontal areas (dorsal and ventral). "
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