When It Comes to Memory, It's All About Location

April 28, 2008

Published: 04/25/08

FRIDAY, April 25 (HealthDay News) -- A new report finds that where

protein-destroying machines reside in the brain's nerve cells may help

determine how memories are formed, a finding that may play a role in future

treatments for Alzheimer's and other brain diseases.

Wake Forest University School of Medicine researchers studying mice

discovered that cylinder-shaped proteasomes, which help control protein

levels, play different roles in controlling synapse strength depending on

where they are in the nerve cells of the hippocampus, an area of the brain

linked to memory.

When humans or animals learn and store information in their memory, these

connections between cells become stronger or weaker, Ashok Hegde, associate

professor of neurolobiology and anatomy at Wake Forest, said in a prepared

statement. For example, if people learn to do something better, such as

playing softball, the synapses that control hand-eye coordination will

become stronger. If they learn to ignore something, such as the barking of a

neighbor's dog, then the synapses that control paying attention will become

weaker.

The findings were published in the current issue of Learning & Memory.

It is known that the degradation of proteins, which are made by cells to

control cell functions, plays an important role in memory function. The team

found that proteasomes in the dendrites -- the branched parts of a neuron

that conduct electrical stimulation -- limit the connection strength between

cells. Proteasomes in the nucleus, which contains the cell's genetic

material, help maintain synapse strength for long periods of time.

The researchers are now trying to learn how to block proteasome activity

specifically in the dendrites of mice to increase the strength of synapses

and of memory. In their ongoing studies, the mice will be analyzed on how

well they can learn to navigate a maze.

" If we see a memory enhancement when we block the proteasome in dendrites, we

can use this strategy to treat memory loss, " Hegde said.

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