Source: Reuters Health News (with whom the copyright remains)
1 September 1999
Scientists say they have created a strain of smart mice by inserting a
gene into the rodents' brains, proving it possible to improve the intelligence of
mammals, [potentially] including humans. The strain of genetically modified mice,
named Doogie, were given extra copies of a gene called NR2B which helped them to learn
faster and to improve their memory.
"They're learning things much better and remembering longer. They're smarter,"
said Joe Tsien, a neurobiologist at Princeton University.
As they aged, the mice also retained certain brain features of juvenile mice which Tsien
and his collaborators at the Massachusetts Institute of Technology and Washington
University said could help to improve learning later in life. The NR2B gene could also be
a potential drug target to eventually treat learning disorders and diseases involving the
decline or loss of memory, such as Alzheimer's, researchers said.
Tsien said the study showed that genetic improvement of learning and memory in
mammals was feasible. He likened the enhanced learning in the mice to increasing
the speed of a top-performance car.
The study revealed that a common biochemical function was at the center of all learning.
It also confirmed a hotly debated theory that memory was created when two neurons formed a
strong connection which is called long-term potentiation or LTP.
"It's a novel approach," said Ira Black, the chairman of neuroscience and cell
biology at Rutgers University. "It's very exciting and holds the hope of not only
making animals smarter but ... ultimately of having a (human) gene therapy for use in
areas such as dementia."
NR2B is a vital switch that controls the brain's ability to associate one
event with another. It works along with a receptor called NMDA, which is
like a signaling station in the brain. As people age, NMDA becomes less responsive, which
is why learning becomes more difficult.
In addition to giving the mice extra copies of NR2B, Tsien programmed the copies so their
activity increased rather than decreased with age, which counteracted the normal activity
of the gene.
Researchers at MIT, led by Guosong Liu, developed a new test to measure the function of
NMDA receptors to confirm that the new gene increased the receptor activity.
At Princeton, Tsien's team put the Doogie mice, named after the lead character in the TV
show Doogie Howser, MD, through a series of tests to confirm their improved learning.
The tests showed the Doogie mice remembered objects four to five times longer than
normal mice and learned faster when given electrical shocks which they associated
with a fear-causing environment.
The researchers tested spatial learning by putting the mice in a pool of water with a
hidden platform which allowed them to climb out of the liquid. The Doogie mice found
the platform after three sessions while the normal mice took six to get it right.
Copyright 1999 Reuters Limited.
Copyright © Laurence D. Watkins (brain@brainsurgery.co.uk) except as stated in the Copyright and other notices
Last update of this page: 03 October 2004