What gives us fingertip dexterity?( Quickly moving your fingertips to ta...),Health

Quickly moving your fingertips to tap or press a surface is essential for everyday life to, say, pick up small objects, use a BlackBerry or an iPhone. But researchers at the University of Southern California say that this seemingly trivial action is the result of a complex neuro-motor-mechanical process orchestrated with precision timing by the brain, nervous system and muscles of the hand.

USC Viterbi School of Engineering biomedical engineer Francisco Valero-Cuevas is working to understand the biological, neurological and mechanical features of the human hand that enable dexterous manipulation and makes it possible for a person to grasp and crack an egg, fasten a button, or fumble with a cell phone to answer a call.

"When you look at the hand, you think, five fingers, what could be more straightforward" Valero-Cuevas said, but really we dont understand well what a hand is bio-mechanically, how it is controlled neurologically, how disease impairs it, and how treatment can best restore its function. It is difficult to know how each of its 30-plus muscles contributes to everyday functions like using a cell phone or performing the many finger tasks it takes to dress yourself.

In a study published online today in The Journal of Neuroscience, titled Neural Control Of Motion-to-Force Transitions with the Fingertip, Valero-Cuevas and co-author Madhusudhan Venkadesan of Cornell Universitys Department of Mathematics asked volunteers to tap and push against a surface with their forefinger while the researchers recorded the fingertip force and electrical activity in all of the muscles of the hand.

These researchers, in a first-of-a-kind experiment, recorded 3D fingertip force plus the complete muscle coordination pattern simultaneously using intramuscular electromyograms from all seven muscles of the index finger. Subjects were asked to produce a downward tapping motion, followed by a well-directed vertical fingertip force aga
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