The magic of the fingers

Quickly use your fingertips to tap or click on a surface that is essential in everyday life, for example, to pick up small objects or use the iPhone. But researchers at the University of Southern California (USC) say that seemingly simple actions are the result of a complex neurological process that is " drafted " with the right time by the brain. , our nervous system and muscles.

Francisco Valero-Cuevas, a biomedical engineer at the USC Viterbi School of Engineering, is currently studying the mechanical, neurological, and biological characteristics of human hands that make them manipulative; Since then humans can hold and break the egg, button the shirt or find the phone to answer the call.

Valero-Cuevas said: 'When you look at your hand, you may think' 5 fingers, nothing more 'but in fact we still don't understand the mechanics and biology of the hand. What is it, how is it controlled by the nervous system, how does it affect it and how can it recover its function? It's hard to understand how more than 30 hands are involved in everyday activities such as using a cell phone or controlling multiple finger movements so that you can dress yourself. '

Valero-Cuevas and the co-author of the study - Cornell University's Madhusudhan Venkadesan of mathematics - asked volunteers to study lightly to tap and press a surface with the index finger while they recorded the force. Finger as well as works with all hand muscles.

Researchers have found that quick finger movement is the result of a complex neurological process that is " drafted " by the brain, nervous system, and hand muscles. . (Artwork: Flickr)

Scientists have done an unprecedented experiment. They recorded finger force in three-dimensional space along with a comprehensive muscle coordination model; At the same time, electromyography was used to analyze all 7 muscle groups on the index finger. Participants were asked to lightly tap in the direction of going down a hard surface followed by performing a vertical force compared to the same surface. The team found that the muscle coordination model has been transformed from motion to force (~ 65 ms) before contacting the surface. Venkadesan's mathematical modeling and analysis discovered that the control of the nervous system also varies between conflicting campaigns of precise time-based operations.

Valero-Cuevas, who held a meeting at the Dentistry School - a specialist in biology and physiotherapy, said: 'We think the human nervous system uses a rigorous neurological strategy. and amazingly accurate time for action that seems simple and easy to type and then push accurately. However, it is an essential component of sophisticated operations'.

'Our data shows that the specialized nervous system evolved at the main hand because of the need for precise neurological activity to make unexpected changes from activity (knocking) to static force ( press). In the typing operation, we found that the brain moved from the typing command to the pressing command while the fingers were still moving. The limitations of neurophysiology make the transition impossible to implement immediately, so we speculate that there is a specialized control system and functions that allow people to act effectively. If the transfer order is not executed promptly and accurately, our initial force will be misleading. We won't be able to hold an egg, a glass of wine or a small particle quickly. '

According to Valero-Cuevas, the results explain why it takes children years to develop the perfect coordination of finger muscles and skills such as grasping or precise manipulation; Besides, the study also explains why manipulating fingertips is easy to be affected by neurological diseases as well as age.

But most importantly, the study offers a functional explanation for the important evolutionary characteristics of the human brain: the motor neuron center and the sense of proportion that is largely related to function. Of hands. Valero-Cuevas said: 'If the nervous system is under the influence of evolutionary pressures, it is possible to precisely and control daily actions (precise and quick grasping), then requires development. cortical structure to be able to combine sensation and movement for the function of fingers'.

'Nervous system is essential to perform action in the correct time as well as control the finger muscles. Our study will explore and provide answers about the function of specialized brain region evolution that controls the manipulation of fingers'.

Understanding the neuromuscular principle behind these operations, Valero-Cuevas hopes to help people who cannot use their hands by guiding them on how to recover with studying a fake hand instead. Besides, research also brings hope to the industry by creating versatile machines equivalent to human hands.

He said: 'Imagine you have to spend your whole life with gloves or when you can hold things that can't be done with it, how much life will be difficult. But millions of people around the world have to live a life without the support of their hands. Disease and aging have affected the function of the hands and reduced the quality of life. And we want to change that. '

The study was published online January 23, 2008 in the journal Neuroscience under the heading ' Moving from motion to force under the impact of the nervous system on fingers '. The study was organized by Whitaker Foundation, The National Science Foundation and The National Institutes of Health sponsored.