Write your abstract here.Brain as memory
machine.
What
happens in our brains when we learn and remember”
Are
memories recorded
in a stable physical change, like writing an inscription permanently on
a clay tablet” Prof. Yadin Dudai, Head of the Weizmann Institute’s
Neurobiology Department, and his colleagues are challenging that view.
They recently discovered that the process of storing long-term memories
is much more dynamic, involving a miniature molecular
machine that must
run constantly to keep memories going. They also found that jamming the
machine briefly can erase long-term memories. Their findings, which
appeared today in the journal Science, may pave the way to future
treatments for memory problems.
Dudai
and research student Reut Shema, together with Todd Sacktor of the SUNY
Downstate Medical Center, trained rats to avoid certain tastes. They
then injected a drug to block a specific protein into the taste cortex
– an area of the brain associated with taste memory. They hypothesized,
on the basis of earlier research by Sacktor, that this protein, an
enzyme called PKMzeta, acts as a miniature memory “machine” that keeps
memory up and running. An enzyme causes structural and functional
changes in other proteins: PKMzeta, located in the synapses – the
functional contact points between nerve cells – changes some facets of
the structure of synaptic contacts. It must be persistently active,
however, to maintain this change, which is brought about by learning.
Silencing PKMzeta, reasoned the scientists, should reverse the change
in the synapse. And this is exactly what happened: Regardless of the
taste the rats were trained to avoid, they forget their learned
aversion after a single application of the drug.
The
technique worked as successfully a month after the memories were formed
(in terms of life span, more or less analogous to years in humans) and
all signs so far indicate that the affected unpleasant memories of the
taste had indeed disappeared. This is the first time that memories in
the brain were shown to be capable of erasure so long after their
formation.
“This
drug is a molecular version of jamming the operation of the machine,”
says Dudai. “When the machine stops, the memories stop as well.” In
other words, long-term memory is not a one-time inscription on the
nerve network, but an ongoing process which the brain must continuously
fuel and maintain. These findings raise the possibility of developing
future, drug-based approaches for boosting and stabilizing memory.
Source: Weizmann Institute of Science