Professional hockey players can make taking the perfect slap shot look easy, whether it's on the ice during a championship game or in a casual game of street hockey. But how their brains can adapt these motor patterns to different situationssuch as wearing heavy protective equipment or notremains a neuroscience puzzle. Behavioral studies suggest that the brain's neural processes use internal models to predict and generate commands for movement based on characteristics of the body and its environment. Currently, two competing theories could explain how these models work. Either a single controlling entity can adapt to any load applied to the body and generate a command, or else multiple controllers exist, each capable of responding to a small set of load situations. A report published today in the journal Nature may help resolve this question. Scientists report that neuronal activity in the brains of monkeys seems to act in a highly structured manner as a single controller.

Paul L. Gribble and Stephen H. Scott of Queen's University in Ontario outfitted monkeys with a robotic sleeve that applied independent forces to their shoulders and arms as they carried out a task. While the animals performed the movement under different conditions, the scientists recorded brain activity in their primary motor cortexes, regions involved in motor control. According to the report, the same neurons responded to pressure applied to both the elbow and the shoulder, even though the forces were administered separately. What is more, how neurons responded to forces applied to a single joint could be used to predict how they would react to a burden shared by two joints. The findings, the authors conclude, "may explain why training on simpler tasks can be transferred and improve performance on related, more complex tasks."