Could veterans of war, rape victims and other people who have seen horrific crimes someday have the traumatic memories that haunt them weakened in their brains? In a new study, UCLA life scientists report a discovery that may make the reduction of such memories a reality. "I think we will be able to alter memories someday to reduce the trauma from our brains," said the study's senior author, David Glanzman, a UCLA professor of integrative biology and physiology and of neurobiology（神经生物学） .

The study appears in the April 27 issue of the Journal of Neuroscience, a premier neuroscience journal.

Glanzman, a cellular neuroscientist, and his colleagues report that they have eliminated, or at least substantially weakened, a long-term memory in both the marine snail known as Aplysia and neurons in a Petri dish. The researchers say they gaining important insights into the cell biology of long-term memory.

They discovered that the long-term memory for sensitization in the marine snail can be erased by inhibiting the activity of a specific protein kinase — a class of molecules that modifies proteins by chemically adding to them a phosphate (an inorganic chemical), which changes the proteins' structure and activity. The protein kinase is called PKM (protein kinase M), a member of the class known as protein kinase C (PKC), which is associated with memory.

The research has important potential implications for the treatment of post-traumatic stress disorder, as well as drug addiction, in which memory plays an important role, and perhaps Alzheimer's disease and other long-term memory disorders.

"Almost all the processes that are involved in memory in the snail also have been shown to be involved in memory in the brains of mammals," said Glanzman, who added that the human brain is far too complicated to study directly.

PKM is rare in that while most protein kinases（蛋白激酶） have both a catalytic domain, which is the part of the molecule that does its work, and a regulatory domain, akin to an on–off switch that can be used by other signaling pathways to shut off the activity of the kinase, PKM has only the catalytic domain — not the regulatory domain.

"This means that once PKM is formed, there is no way to shut it off," said Glanzman, who is a member of UCLA's Brain Research Institute. "Once it is activated, PKM's continual activity maintains a memory until PKM degrades."

Glanzman decided to study PKM in the marine snail, which has simple forms of learning and a simple nervous system, so that he could understand in precise detail how PKM's activity maintains a long-term memory, a process that is not well understood.

Glanzman and his colleagues — researchers Diancai Cai, lead author of the study; Kaycey Pearce; and Shanping Chen, all of whom work in his laboratory — studied a simple kind of memory called sensitization. If marine snails are attacked by a predator, the attack heightens their sensitivity to environmental stimuli — a "fundamental form of learning that is necessary for survival and is very robust in the marine snail," Glanzman said.