Brain cells rewire to memorise new tasks

Washington, Nov 30 ( Brain cells memorise a new task by rewiring themselves as soon as it is performed, says a new study.

University of California, Santa Cruz (UCSC) researchers made detailed observations of the rewiring processes that take place in the brain following an activity.

They studied mice trained to reach through a slot to get a seed. They observed rapid growth of structures that form connections (called synapses) between nerve cells in motor cortex, the brain layer that controls muscle movements.

“We found very quick and robust synapse formation almost immediately, within one hour of the start of training,” said Yi Zuo, assistant professor of molecular, cell and developmental biology at UCSC.

“We initiated the motor learning studies to understand the process that takes place after a stroke, when patients have to relearn how to do certain things. We want to find out if there are things we can do to speed up the recovery process,” Zuo said.

Zuo’s team observed the formation of structures called dendritic spines. They form synapses with other nerve cells (neurons). At those synapses, the neurons receive input from other brain regions involved in motor memories and muscle movements.

The researchers found that growth of new dendritic spines was followed by selective elimination of pre-existing spines, so that the overall density of spines returned to the original level.

“It’s a remodelling process in which the synapses that form during learning become consolidated, while other synapses are lost,” Zuo said, according to a UCSC release.

“When you learn to ride a bicycle, once the motor memory is formed, you don’t forget. The same is true when a mouse learns a new motor skill; the animal learns how to do it and never forgets.”

Understanding the basis for such long-lasting memories is an important goal for neuroscientists, with implications for efforts to help patients recover abilities lost due to stroke or other injuries.

These findings were published in Nature.