Practice makes for more efficient generation of neuronal activity in the primary motor cortex, the area of the brain that plans and executes movement, according to researchers from the University of Pittsburgh School of Medicine.
They found that practice leads to decreased metabolic activity for internally generated movements, but not for visually guided motor tasks, and suggest the motor cortex is "plastic" and a potential site for the storage of motor skills.
The hand area of the primary motor cortex is known to be larger among professional pianists than in amateur ones.
Prior imaging studies have shown that markers of synaptic activity, meaning the input signals to neurons, decrease in the primary motor cortex as repeated actions become routine and an individual develops expertise at a motor skill.
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The researchers found that markers of synaptic activity also display a marked decrease in monkeys trained to perform sequences of movements that are guided from memory - an internally generated task - rather than from vision.
All the monkeys were trained on two tasks and were rewarded when they reached out to touch an object in front of them. In the visually guided task, a visual target showed the monkeys where to reach and the end point was randomly switched from trial to trial.
In the internally generated task the monkeys were trained to perform short sequences of movements without visual cues. They practiced the sequences until they achieved a level of skill comparable to an expert typist.
However, metabolic activity was high for the visually guided task, but only modest during the internally generated task.
"What is really important is that our results indicate that practice changes the primary motor cortex so that it can become an important substrate for the storage of motor skills. Thus, the motor cortex is adaptable, or plastic," Strick said.
The study was published in journal Nature Neuroscience.