Functioning much like gears in a machine, cellular motor proteins are critical to dynamic（动态的，动力的） functions throughout the body, including muscle contraction, cell migration and cellular growth processes. Now, neuroscientists from UC Irvine and the Florida campus of The Scripps Research Institute report that motor proteins also play a critical role in the stabilization of long-term memories. The findings add an unexpected dimension to the story of how memories are encoded（编码） and suggest new targets for therapeutic interventions. UCI's Christopher Rex and Gavin Rumbaugh at Scripps found that myosin II proteins, more commonly studied in muscle contraction and cell migration, are critical for functional brain plasticity and learning. The work builds on a fundamental theory of memory – posed over 25 years ago by UCI neuroscientist（神经系统科学家） Gary Lynch – that memories are the product of structural rearrangements of synapses（突触） in the brain.

"We suspected that motor proteins are involved in synaptic plasticity," said Rumbaugh, an assistant professor of neuroscience. "Now that we know that they are, we can begin to investigate how the vast literature on motor proteins from other cell types may generalize to neurons."

Study results appear in the Aug.26 issue of Neuron.

Myosin II motors are one of the most studied protein complexes in the human body. They are best known for interacting with actin filaments（肌动蛋白丝） to control initiate forces within cellular compartments.

"Cells are constructed like buildings," said Rex, a Kauffman Foundation Fellow in anatomy（解剖） & neurobiology. "Actin can be thought of as the building's frame, meaning it determines the scale and design of the structure. Myosin II would then be like a crane moving the beams into place. The main difference being that myosin（肌浆球蛋白） II is poised to both tear down and rebuild the structure with a completely different design at any minute."

A core tenant（承租人，房客） of contemporary theory is that the sizes and shapes of dendritic spines（树突刺） , small protrusions（突出） at the receiving end of chemical transmission at synapses, are critical for determining synaptic strength.

"We know that appropriate patterns of neuronal activity can cause structural changes to these elements spines, now our major focus is to understand how this works," said Lynch, who contributed to the study.

Having discovered that a submicroscopic（亚微观的） motor drives synaptic reorganization, the UCI and Scripps research groups believe they are substantially closer to understanding how to selectively enhance memory formation, and thereby treat the memory problems associated with aging, post-traumatic（外伤的） stress, mental retardation（智力迟钝） and age-related neurodegenerative diseases.