Wednesday, September 1, 1999 Published at 21:11 GMT 22:11 UK
Genetic engineering boosts intelligence
Doogie remembered objects for longer
US researchers have genetically modified mice to be better at learning and remembering. Team leader Joe Tsien, a neurobiologist at Princeton University said simply: "They're smarter."
The breakthrough will ignite debate about whether such a feat would be ethical but Ira Black, chairman of neuroscience at Rutgers University says: "It's very exciting and holds the hope of not only making animals smarter but also, ultimately, of having a human gene therapy for use in areas such as dementia."
However, Dr Tim Bliss, head of neurophysiology at the National Institute for Medical Research in London, said: "When you insert a gene at random into the genome you don't know what might happen. These animals seem to be OK, but there might be all sorts of hidden down sides to having this extra protein.
"I think it's very unlikely that tinkering with one gene is going to increase intelligence and do nothing else. In my view talk of genetically enhancing human intelligence is nonsense."
However, he said new drug or gene therapy treatments might emerge from the research. "It certainly raises that possibility, but we are very far away at the moment."
Smart young things
The research team from Princeton, Washington and MIT universities found that adding a single gene to mice significantly boosted the animals' ability to solve maze tasks, learn from objects and sounds in their environment and to retain that knowledge.
This new strain of mice is named Doogie, after a precocious character on the US television show Doogie Howser, MD.
One key feature of learning is the ability to associate one event with another - associating fire with the sensation of pain is a simple example. The research shows that the gene used, called NR2B, is very important in controlling this ability.
It is the blueprint for a protein that spans the surface of neurons and serves as a docking point, or receptor, for certain chemical signals. This receptor, called NMDA, is like a double lock on a door; it needs two keys or events before it opens.
Studies have shown that in young animals the NMDA receptor responds even when the two events happen relatively far apart, so it is easier to make connections between events and to learn. After adolescence, the receptor becomes less responsive, making learning more difficult. But introducing the NR2B gene kept the Doogie mice's brains "young".
Showing that the Doogie mice were more intelligent required a number of tests:
The research results will help researchers trying to understand and treat human disorders that involve the loss of learning and memory. The NR2B gene would be a potential target for drug makers trying to design medicines that boost its effects, but this remains many years away.