PKMzeta is produced in the brain in response to learning, and it acts on the synapses – the active contact points between neurons. It continues to operate there long after the memory has been formed, suggesting that its function is tied not to absorbing information but to keeping what is learned available in the long-term memory.
In 2007, Prof. Yadin Dudai and research student Reut Shema of Weizmann’s neurobiology department, together with Prof. Todd Sacktor of SUNY Downstate Medical Center, New York, trained rats to avoid a specific taste and then blocked the activity of PKMzeta in their brains. While the control rats still had a strong aversion to the taste, even months after the training, those in which the activity of the protein was briefly blocked had no such qualms, appearing to have forgotten what they had learned.
Wondering if extra doses of PKMzeta might actually improve memory, the researchers teamed up with colleagues Dr. Alon Chen and Sharon Haramati to create harmless viruses that carry extra copies of the PKMzeta gene into the brain cells’ nucleus, tricking the neurons into producing greater quantities of the protein.
Once again, they trained the rats to avoid the taste. Weeks later, the rats whose brains were making more PKMzeta were much more likely to avoid the taste. This is the very first demonstration that memories formed long ago can be augmented by manipulating a component of the memory machinery in the brain.
In the future, these findings might point to ways of preventing or treating memory loss.