Families affected by fragile X syndrome can let out a modest cheer this week: the largest-ever randomized trial of a drug to treat the syndrome has just cleared its second phase.

The biology of obsessive-compulsive disorder becomes even more baffling with the release of two new mouse models, each implicating a different type of brain cell.

A study of a rare form of epilepsy found in Amish groups adds heft to the idea that mTOR — a much-studied hub in a massive network of brain cell proteins — is an important biochemical player in autism.

Mice engineered to carry a well-known risk factor for schizophrenia show disruptions in the connections between two brain regions that coordinate memory and learning. And these disruptions directly cause problems with working memory — the ability to actively hold information and to recall that information to make a decision, according to a study published in Nature.

A new model that compares how the same genes behave in different organisms could help researchers identify previously unknown candidates for diseases such as autism. The model, published in the Proceedings of the National Academy of Sciences, takes advantage of the genetic overlap between humans and simpler organisms to discover genes associated with complex diseases.

Among animal models of autism, the mouse reigns supreme. But could much simpler species — flies, bees, worms, fish — also teach us about the disorder?

Researchers are tinkering with mouse models to investigate the function of a protein that helps wire neurons together and that has repeatedly been linked to autism. Three such reports of the protein, neuroligin-1, have appeared this year.

Two independent teams have discovered key molecular steps in the way a single gene disrupts the connections between neurons in individuals with Angelman syndrome. Because the gene, UBE3A, has also been linked to autism, the findings could help scientists understand and treat a range of neurodevelopmental disorders.

Several studies in the past year in people, mice and honeybees have tied autism to a protein that helps neurons communicate. Problems with the protein, neurexin 1, are associated with a wide range of autistic behaviors, such as impaired social interactions, anxiety and problems with learning and memory.

Writing in Science, leading scientists call for a 10-year, $2 billion international scheme that would combine the latest in genetics and animal research to combat psychiatric diseases.