When a gene implicated in human autism is disabled in mice, the rodents show learning problems and obsessive, repetitive behaviors

The researchers also report that a drug affecting a specific type of nerve function reduced the obsessive behavior in the animals, suggesting a potential way to treat repetitive behaviors in humans. The study focused on a protein called neuroligin 1, or NL1, which helps physically hold nerve cells together so they can communicate better with one another. Mutations in proteins related to NL1 have been implicated in previous investigations to human autism and mental retardation. In the latest study, the UT Southwestern researchers studied mice that had been genetically engineered to lack NL1. These mice were normal in many ways, but they groomed themselves excessively and were not as good at learning a maze as normal mice. The altered mice showed weakened nerve signaling in a part of the brain called the hippocampus, which is involved in learning and memory, and in another brain region involved in grooming. When treated with a drug called D-cycloserine, which activates nerves in those brain regions, the excessive grooming lessened.