How brain helps serve the perfect Tennis ace

A new research has shed light on how brain can differentiate between the errors of different magnitudes, like while, fine-tuning a tennis serve; the brain has to distinguish whether it needs to make a slight rectification if the ball barely misses the target or a much bigger correction if it is way off.

University of Pennsylvania researchers have made another advance in understanding how the brain detects errors caused by unexpected sensory events. This type of error detection is what allows the brain to learn from its mistakes, which is critical for improving fine motor control.

The movements are controlled by neurons known as Purkinje cells. Each muscle receives instructions from a dedicated set of hundreds of these brain cells. The instructions sent by each set of Purkinje cells are constantly fine tuned by climbing fibers, a specialized group of neurons that alert Purkinje cells whenever an unexpected stimulus occurs.

Javier Medina, an assistant professor in the Department of Psychology in Penn's School of Arts and Sciences, said that an unexpected stimulus would often be a sign that something has gone wrong.

These error signals are mixed in with random firings of the climbing fibers, however, and researchers were long mystified about how the brain tells the difference between this noise and the useful, error-related information it needs to improve motor control.

Researchers found that the eyelid-associated Purkinje cells filled with different amounts of calcium depending on the length of the puff; the longer ones produced larger spikes in calcium levels.

The study could help explain how practice makes perfect, even when errors are imperceptibly small.

The study is published in the journal eLife.