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Published on: February 21, 2018
Early myelination patterns in the central auditory pathway of the higher brain: MRI evaluation study
Masaki Sano1, Chen-Chieh Kuan, Kimitaka Kaga
1Department of Otorhinolaryngology and Head & Neck Surgery, Graduate School of Medicine and Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. neurootolsano@ybb.ne.jp
Objective:
The purpose of this study was to use magnetic resonance imaging (MRI) to investigate the early myelination patterns of the central auditory pathway and then compare the data with past histological research. We observe the MRI signal intensity of the central auditory pathway and clarify the time course difference between MRI and previous histological research studies.
Methods:
A total of 192 infants ranging in age from -4 to 224 corrected postnatal weeks were included in the study. Images were obtained using a 1.5 T MR unit. We chose three sites (medial geniculate body, auditory radiation, and splenium of the corpus callosum) of the central auditory pathway for analysis. Three cross sections were obtained perpendicular to the long axis of the brain and used to analyze the signal changes of the T1- and T2-weighted MRI by employing a region-of-interest (ROI) methodology that was corrected for postnatal age.
Results:
At 10 corrected postnatal weeks, the medial geniculate body showed myelinated intensity changes on T2-weighted images. Auditory radiation showed myelinated intensity changes at 19 corrected postnatal weeks on the T1-weighted images and at 24 corrected postnatal weeks on the T2-weighted images. The splenium of the corpus callosum showed myelinated intensity changes at 16 corrected postnatal weeks on T1-weighted images and at 24 corrected postnatal weeks on T2-weighted images.
Conclusions:
As compared to the histological literature, the MRI documented signal intensity changes caused by myelination occurred approximately 3 weeks later for the medial geniculate body, 7-24 weeks later for the auditory radiation and 7-15 weeks later for the splenium of the corpus callosum. Since myelination is a process that occurs gradually, substantial changes of the myelin sheath makeup, a loss of water and the addition of lipids are more required in order to be detectable by MRI than myelin staining of histological study.
Insights
Magnetic resonance imaging (MRI) reveals early myelination in infant auditory pathways, with signal changes appearing later than traditional histological studies. This research clarifies the timing differences in detecting myelination using MRI versus histology.
Area of Science:
- Neuroscience
- Developmental Biology
- Medical Imaging
Background:
- Myelination is a critical process in central nervous system development, particularly for the auditory pathway.
- Understanding the timing of myelination is essential for assessing neurological development and identifying potential abnormalities.
Purpose of the Study:
- To investigate early myelination patterns in the central auditory pathway using magnetic resonance imaging (MRI).
- To compare MRI-derived myelination timing with established histological findings.
- To clarify the temporal discrepancies between MRI signal intensity changes and histological evidence of myelination.
Main Methods:
- 192 infants aged -4 to 224 corrected postnatal weeks underwent MRI scans on a 1.5 T unit.
- Analysis focused on three central auditory pathway sites: medial geniculate body, auditory radiation, and splenium of the corpus callosum.
- Region-of-interest (ROI) methodology was applied to T1- and T2-weighted MRI scans to analyze signal changes, corrected for postnatal age.
Main Results:
- Myelinated intensity changes in the medial geniculate body were observed at 10 corrected postnatal weeks on T2-weighted images.
- Auditory radiation showed myelination-related signal changes at 19 weeks (T1-weighted) and 24 weeks (T2-weighted).
- The splenium of the corpus callosum exhibited myelination changes at 16 weeks (T1-weighted) and 24 weeks (T2-weighted).
Conclusions:
- MRI detected myelination signal intensity changes approximately 3 weeks later in the medial geniculate body, 7-24 weeks later in the auditory radiation, and 7-15 weeks later in the splenium of the corpus callosum compared to histological data.
- The gradual nature of myelination, involving significant changes in myelin sheath composition (water loss, lipid addition), requires more advanced changes for MRI detection than for histological staining.
- MRI provides a valuable, non-invasive method for assessing central auditory pathway myelination, though its temporal resolution differs from histological methods.
