Neuroscience Gateway (September 2007) | doi:10.1038/aba1779
Mice with a mutation associated with autism show deficits in social behaviors and increased inhibitory neurotransmission, consistent with the suggestion that autism can result from excessive inhibition.
Out of hundreds of possibilities, just one can occasionally get the job done. Gene-association studies have identified many candidate genes associated with autism. Now Tabuchi et al. report that mice with one disease-associated mutation show behavior consistent with autism in a recent article in Science.
Researchers previously identified mutations in the cell-adhesion molecules neuroligin-3 and 4 in familial forms of autism. Neuroligins are synaptic proteins that bind to neurexins, which have also been associated with autism. Mice express a homolog to neuroligin-3.
The authors generated mice with an autism-associated arginine-to-cysteine mutation in the extracellular domain of neuroligin-3 (R451C). R451C mutant mice showed normal locomotor, motor and anxiety behaviors. However, these mice showed abnormal social behaviors. Although R451C mutant and wild-type mice explored unfamiliar objects for similar lengths of time, relative to wild-type mice, R451C mutant mice spent less time interacting with unfamiliar mice that were enclosed in transparent cages. However, R451C mutant and wild-type mice interacted similarly with freely moving mice, suggesting that R451C mutant mice show deficits in the initiation of social interactions, like people with autism.
Some people with autism show enhanced cognitive skills. In the Morris water maze, R451C mutant mice learned the location of a submerged platform faster than did wild-type mice. When the platform was removed, R451C mutant mice swam past its former location more than did wild-type mice, suggesting enhanced spatial memory in the mutant mice.