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Published on: January 23, 2017
Morphometric differences in the Heschl's gyrus of hearing impaired and normal hearing infants
Kristen M Smith1, Marc D Mecoli, Mekibib Altaye
1Pediatric Neuroimaging Research Consortium, Cincinnati Children's Research Foundation, Cincinnati, OH, USA.
Insights
Hearing impairment in infants alters brain structure, showing increased gray matter and decreased white matter in the auditory cortex. This structural change impacts the typical brain asymmetry observed in normal-hearing infants.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Auditory Neuroscience
Background:
- Heschl's gyrus and primary auditory cortex (PAC) are crucial for auditory processing.
- Understanding structural brain changes in infants with hearing impairment (HI) is vital for early intervention.
- Morphometric differences in the auditory cortex may result from auditory deprivation.
Purpose of the Study:
- To investigate the morphometry of Heschl's gyrus and PAC in infants with normal hearing (NH) and HI.
- To compare gray matter (GM) and white matter (WM) volumes between HI and NH infants.
- To examine hemispheric asymmetry patterns in the auditory cortex of infants.
Main Methods:
- High-resolution 3D magnetic resonance imaging (MRI) was used on 42 infants (8–19 months).
- Automatic brain imaging segmentation software estimated GM and WM volumes within defined regions of the anterior Heschl's gyrus (aHG).
- Analysis of variance and whole-brain voxel-based morphometry were employed to analyze group differences.
Main Results:
- Infants with HI exhibited increased GM and decreased WM in the aHG compared to NH infants.
- The typical left > right (L > R) asymmetry in aHG volume was absent in the HI group.
- Increased GM in HI infants may indicate abnormal PAC development, while decreased WM aligns with findings in deaf adults.
Conclusions:
- Auditory deprivation in infants leads to significant structural alterations in Heschl's gyrus and PAC.
- These findings highlight the impact of early hearing impairment on brain development and cortical organization.
- The observed morphometric changes suggest potential targets for therapeutic interventions in infants with hearing loss.
Abstract:
This study investigates the morphometry of Heschl's gyrus and its included primary auditory cortex (PAC) in hearing impaired (HI) and normal hearing (NH) infants. Fourty-two infants, age 8-19 months, with NH (n = 26) or hearing impairment (n = 16) were studied using high-resolution 3D magnetic resonance imaging. Gray matter (GM) and white matter (WM) volumes were obtained using software for automatic brain imaging segmentation to estimate the volume of each tissue within manually defined regions for the anterior portion of Heschl's gyrus (aHG) in each individual subject, transformed to an infant brain template space. Interactions among group (HI, NH), tissue type (GM, WM), and hemisphere (left, right) were examined using analysis of variance. Whole-brain voxel-based morphometry was utilized to explore volume differences between groups across the entire brain. The HI group showed increased GM and decreased WM in aHG compared with the NH group; likely effects of auditory deprivation. The HI group did not exhibit their typical L > R asymmetry pattern that the NH group showed. Increased GM in aHG in HI infants may represent abnormal cortical development in PAC as seen in animal models of sensory deprivation. Lower WM volume is consistent with studies with deaf adults.
