“These results do not show that PKM-ζ is unimportant,” says Lynn Nadel, a cognitive scientist at the University of Arizona in Tucson. “But they show that the situation is complicated—surprise!—and that there are multiple possible pathways involved.”
These other pathways are still a mystery. Without PKM-ζ, “there are not many compelling alternatives for how long-term memory is maintained,” says Huganir. His team is now trying to explore other mechanisms by identifying ZIP’s true targets. “The mechanisms underlying the maintenance of long-term memory will be one of the more exciting areas of neuroscience research for many years to come,” he says.