A SINGLE molecule helps mice to recall terrifying experiences, say scientists
in Europe. Mice that lack the protein quickly forget frightening events that
normal mice remember for days.
One way to study memory is to damage areas of animals’ brains and evaluate
their mental deficiencies. But Riccardo Brambilla and Rüdiger Klein of the
European Molecular Biology Laboratory in Heidelberg, Germany, and their
colleagues bred mice with a specific memory problem by disrupting a single gene.
“This is a more molecular approach to what others have done with lesions,” says
The gene makes a protein called Ras-GRF, which is usually found throughout
the developing brain and is thought to help transmit signals that regulate cell
division. But the brains of mice that lack Ras-GRF appear entirely normal.
Nevertheless, the mutant mice forget things that frightened them. When given
an electric shock upon entering a box, for example, they avoid the box half an
hour later. But the next day they march right in, although their normal peers
are still afraid.
Not all long-term memory is disrupted in these mice. For example, they can
remember the position of a platform submerged in milky water for days. The
experiments, which are reported in this week’s Nature (vol 390, p 281), also
show that general learning and short-term memory are left intact.
Klein plans to find out the biochemical function of Ras-GRF. He hopes the
molecular approach will also help to show where and how the brain processes
different types of memory.