The study found that a genetic mutation, known as 22q11 deletion and common in schizophrenia patients, hinders communication between the hippocampus and the prefrontal cortex, the researchers wrote in the online edition of the journal Nature (www.nature.com/nature).
What we're showing here is that this particular genetic mutation disrupts the communication between these two brain regions and thereby causes the problems with cognition, Dr. Joshua Gordon of Columbia University in New York said in a telephone interview.
This is the first step in identifying... what's wrong here in these brain regions, and with a little bit more understanding, then we can imagine being able to design therapies that help the two brain regions talk to each other, Gordon said.
Schizophrenia, characterized by hallucinations, delusions and disordered thinking, is far more common in men than in women and is usually diagnosed in late adolescence or early adulthood. It affects around an estimated one in 100 people.
While anti-psychotic drugs such as AstraZeneca's Seroquel and Eli Lilly and Co's Zyprexa can help, such drugs do not cure the mental illness and can cause unpleasant side-effects, including sometimes dangerous weight gain.
And we've now tied those deficits both to a specific genetic mutation and also to the behavior itself, he added.
In the study, Gordon and colleagues put both healthy mice and mice with the gene mutation through a memory-testing challenge and recorded the animals' brain activity.
The mice had to negotiate a maze and remember the direction in which they traveled and then choose to go in the opposite direction in order to receive a reward.
The successful completion of the task in the healthy mice required the hippocampus and the prefrontal cortex to work together, Gordon said.
We could see that this was happening in the mice carrying the schizophrenia mutation... but they weren't able to synchronize their activity to the same extent, he said. So it was as if these two areas could not talk to each other as well as they should.
Gordon said they have shown the troubled communication between the two brain regions in animals with the gene mutation, but more research is needed to determine whether the theory holds true for humans who carry the mutation.