SUPERSMART mice created by a team of researchers in New Jersey seem to be
shedding some light on how memories are recalled in humans.
Joe Tsien and his colleagues at Princeton University engineered the mice to
test a theory about memories proposed in 1949 by Canadian psychologist Donald
Hebb. Hebb argued that when memories form, a cluster of neurons strengthen their
connections. When a memory is recalled, the neurons activate simultaneously.
So neurons must have a way of 鈥渒nowing鈥� when others in the cluster are
active. 快猫短视频s had speculated that this may involve a receptor called NMDA.
This will make a neuron fire only if it receives stimuli from two other
neurons.
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Now Tsien and his colleagues have dramatic new proof that NMDA is indeed
involved in memory. They genetically altered mice so that they had more versions
of a key section of NMDA receptors than usual. Compared with normal mice, the
transgenic mice performed much better in several different tests of learning and
memory such as in water mazes, object recognition and association of cages or
sounds with mild electric shocks on their feet.
In some cases, normal mice would retain a memory for only one day while a
mutant mouse could remember for five days (Nature, vol 401, p 63). 鈥淲e
were very surprised,鈥� says Ya-Ping Tang, one of the team. He had expected to see
some memory improvement, but not on so many diverse tasks.
Researchers welcomed the study as strong new support that NMDA plays an
important role in memory and learning. 鈥淚 think this is extremely important.
Anything that enhances memory is interesting, and this is such a clear-cut
result,鈥� says Eric Kandel of Columbia University in New York, who has studied
engineered mice with poor memories.
So do the supersmart mice suggest we can improve people鈥檚 memories and
learning abilities in the same way? Tim Bliss of the National Institute for
Medical Research in Mill Hill, London, says there鈥檚 no reason to think so.
鈥淭hese are mice that are living a very simple life. You give them a few tests
and they do better. It鈥檚 science fiction in terms of doing anything with
humans,鈥� he argues. 鈥淣obody for a minute would think it would be a good idea to
overexpress a gene in a human baby.鈥�
But Kandel speculates that studies like this could one day result in
treatments for people with impaired memory. 鈥淥ne would ultimately like to be
able to improve memory鈥攏ot to produce superior human beings, but to treat
age-related memory loss or mental retardation,鈥� he says.