Using a flash of light, scientists have inactivated and then reactivated a memory in genetically engineered rats. The study, supported by the National Institutes of Health, is the first cause-and-effect evidence that strengthened connections between neurons are the stuff of memory.
"Our results add to mounting evidence that the brain represents a memory by forming assemblies of neurons with strengthened connections, or synapses, explained Roberto Malinow, M.D., Ph.D., of the University of California, San Diego (UCSD), a grantee of the NIH's National Institute of Mental Health (NIMH). "Further, the findings suggest that weakening synapses likely disassembles neuronal assemblies to inactivate a memory."
Malinow, Roger Tsien, Ph.D., a grantee of NIH's National Institute on Neurological Disorders and Stroke (NINDS), and other UCSD colleagues, report June 1, 2014 in the journal Nature on their findings using cutting edge optical/gene-based technology.
"Beyond potential applications in disorders of memory deficiency, such as dementia, this improved understanding of how memory works may hold clues to taking control of runaway emotional memories in mental illnesses, such as post-traumatic stress disorder," said NIMH director Thomas R. Insel, M.D.
Neuroscientists have long suspected that strengthened connections between neurons – called long-term potentiation (LTP) – underlies memory formation, But proof had remained elusive, until now.