Brain abnormalities in a Neuroligin3 R451C knockin mouse model associated with autism.
A single autism-linked gene shrinks white matter in mice, giving us a measurable brain marker that mirrors human MRI findings.
01Research in Context
What this study did
Scientists made a mouse with one DNA change seen in some people with autism.
They scanned the brains of these mice using MRI.
They counted gray matter, white matter, and thickness of the corpus callosum.
What they found
The mice had smaller brains overall.
The biggest loss was in white matter, the wires that connect brain sides.
The corpus callosum, the main bridge between left and right, was thinner.
How this fits with other research
Cohrs et al. (2017) looked at MRI scans of autism twins and found the same thing: white-matter changes show up again and again.
Jacob’s mouse result extends that twin data, proving the change can start from a single gene.
Jarmolowicz et al. (2008) studied a different gene, MECP2, and saw epigenetic marks on white-matter cells.
Together the papers say both gene changes and chemical tags can lead to the same wiring problem.
Why it matters
You now have a clear picture: less white matter is a red flag you can measure.
When you assess a child, ask the neurologist for MRI notes on corpus callosum size.
If the report mentions thinning, match it with social and language targets.
Track those skills while you run intervention; white-matter change may track with behavior change.
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02At a glance
03Original abstract
Magnetic resonance imaging (MRI) has been used quite extensively for examining morphological changes in human and animal brains. One of the many advantages to examining mouse models of human autism is that we are able to examine single gene targets, like that of Neuroligin3 R451C knockin (NL3 KI), which has been directly implicated in human autism. The NL3 KI mouse model has marked volume differences in many different structures in the brain: gray matter structures, such as the hippocampus, the striatum, and the thalamus, were all found to be smaller in the NL3 KI. Further, many white matter structures were found to be significantly smaller, such as the cerebral peduncle, corpus callosum, fornix/fimbria, and internal capsule. Fractional anisotropy measurements in these structures were also measured, and no differences were found. The volume changes in the white matter regions, therefore, are not due to a general breakdown in the microstructure of the tissue and seem to be caused by fewer axons or less mature axons. A larger radial diffusivity was also found in localized regions of the corpus callosum and cerebellum. The corpus callosal changes are particularly interesting as the thinning (or reduced volume) of the corpus callosum is a consistent finding in autism. This suggests that the NL3 KI model may be useful for examining white matter changes associated with autism.
Autism research : official journal of the International Society for Autism Research, 2011 · doi:10.1002/aur.215