Two new studies provide clues that may explain sex differences in autism prevalence. Italian researchers have found that injecting estrogen into the brains of young male mice reverses some of the structural and behavioral changes associated with low levels of reelin — a brain protein that has been previously implicated in autism — and the effects endure into adulthood.

Telling jokes allows children to connect with others, refine their language skills and develop keen imaginations. Because these are precisely the skills lacking in people with autism, studying humor in children with the disorder may give insights into their abnormal brain circuitry and even lead to therapies, according to a review published in the Journal of Child Neurology.

Children with autism are less likely to yawn when others do, perhaps because they tend not to unconsciously mimic behavior.

Damage to the amygdala — a region of the brain that regulates emotional processing — does not cause autism, according to a study of two individuals with lesions in the region. The study, published in September in the Journal of Neurodevelopmental Disorders, found that these individuals show no evidence of autism when given multiple diagnostic tests.

A study of postmortem brain tissue shows that RPP25, a gene on the autism-linked 15q22-26 chromosomal region, is expressed differently in the brains of people with the disorder. This is the first time this gene has been implicated in autism.

A study of postmortem tissue shows that microglia, cells that provide immune protection to the brain, are altered in the brains of individuals with autism.

Genes responsible for Alzheimer’s disease and fragile X syndrome — a form of mental retardation linked to autism — may operate through the same pathway, according to a study published in The Journal of Neuroscience.

A drug that interferes with a biochemical pathway important in cancer can reverse some brain defects in mouse models of fragile X syndrome, according to a study published 11 August in the Journal of Neuroscience.

In order to understand the interaction between genes and environment in autism, researchers in different disciplines will have to move back and forth between those two realms, stretching out of their intellectual comfort zones. But if the mood at an interdisciplinary workshop two weeks ago is any indication, that challenge is also a source of excitement.

Individuals with autism have trouble perceiving the passage of time, and pairing sights and sounds that happen simultaneously, according to two new studies.