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Flash visual evoked potentials in the hypomyelinated mutant mouse shiverer
Donna M Lehman1, Joseph M Harrison
1Department of Ophthalmology, The University of Texas Health Science Center, San Antonio 78229-3900, USA.
Abstract:
Myelin basic protein (MBP) is an essential component of central nervous system (CNS) myelin, as demonstrated by shiverer mutant mice that have deletions of most of the Mbp structural gene. These mutants do not produce detectable MBP protein, and their CNS is hypomyelinated. Although the function of the visual pathway is presumed to be adversely affected by hypomyelination of the optic nerve, it has never been studied. We compared flash visual evoked potentials (FVEPs) of shiverer homozygotes with those of their wild-type littermates in order to characterize any dysfunction. There was a statistically significant delay in the implicit times of a negative component peaking at 85 ms and a large positive component peaking at 170 ms in the FVEPs of the shiverer mice. The amplitudes of the two components did not differ significantly in the shiverers and wild-type controls. Barring a retinal pathology, which cannot be excluded by these data, the delayed FVEP of the shiverer can likely be attributed to effects of hypomyelination of the optic nerve, optic tract and visual radiations on conduction time in the visual pathway and subsequent further post-synaptic delays.
Insights
Shiverer mutant mice lacking myelin basic protein (MBP) show delayed visual evoked potentials (FVEPs). This suggests hypomyelination impairs central nervous system visual pathway function.
Area of Science:
- Neuroscience
- Genetics
- Ophthalmology
Background:
- Myelin basic protein (MBP) is crucial for central nervous system (CNS) myelin.
- Shiverer mutant mice lack detectable MBP and exhibit CNS hypomyelination.
- The impact of this hypomyelination on visual pathway function remains unstudied.
Purpose of the Study:
- To investigate visual pathway dysfunction in shiverer mutant mice.
- To characterize alterations in flash visual evoked potentials (FVEPs) associated with MBP deficiency.
Main Methods:
- Comparison of FVEPs between shiverer homozygotes and wild-type littermates.
- Analysis of implicit times and amplitudes of FVEP components.
Main Results:
- Statistically significant delays were observed in FVEP components peaking at 85 ms and 170 ms in shiverer mice.
- No significant differences in FVEP component amplitudes were found between shiverer and wild-type mice.
Conclusions:
- Delayed FVEPs in shiverer mice likely result from hypomyelination affecting optic nerve, tract, and visual radiations.
- This indicates impaired conduction time and post-synaptic delays within the visual pathway due to MBP deficiency.