Feb. 13 (HealthDay News) -- The lack of a particular brain protein may explain the phenomenon of "Rain Man" -- autistic savants who learn some tasks better but also forget faster, say researchers at Massachusetts Institute of Technology.

Mice genetically engineered to lack a key protein used for building synapses -- the junctions through which brain cells communicate -- actually learned a spatial memory task faster and better than normal mice, according to findings in the Feb. 13 issue of the Journal of Neuroscience. But when tested weeks later, the altered mice couldn't remember what they had learned as well as normal mice, and they had trouble remembering contexts that should have provoked fear.

"These opposite effects on different types of learning are reminiscent of the mixed features of autistic patients, who may be disabled in some cognitive areas but show enhanced abilities in others," study co-author Albert Y. Hung, a staff neurologist at Massachusetts General Hospital, said in a prepared statement. "The superior learning ability of these mutant mice in a specific realm is reminiscent of human autistic savants."

The absence of this important synaptic scaffold protein, called Shank1, may "trap" the mice's synapses into a state in which the synapses are ready to respond to input but not maintain it in long-term memory, he said.

In humans, mutations in the closely related protein Shank3 have been linked to the autism spectrum of disorders (ASD) characterized by impaired social interaction, absent or delayed language development and repetitive behaviors. Occasionally, an autistic person has an outstanding skill, such as an incredible rote memory or musical ability. Such individuals, like the character Dustin Hoffman played in the film "Rain Man," may be referred to as autistic savants.

SOURCE: Massachusetts Institute of Technology, news release, Feb. 12, 2008