But the brain processes that make the two different streams of 'e's are utterly different, according to a study done by a University of Southern California neural specialist and colleagues.
The insight may lead to, among other things, better movement control by humanoid robots, but also new ways of movement rehabilitation. And perhaps it even offers some insight into the effect of music.
Dr. Stefan Schaal, an associate professor in the computer science department of the USC Viterbi School of Engineering led the international team that used functional Magnetic Resonance Imaging (fMRI) scans to test a longstanding question regarding "rhythmic" versus "discrete" movement.
"Rhythmic movements like walking, chewing or scratching are found in many organisms, ranging from insects to primates," notes Schaal in an article published in Nature Neuroscience Sept. 26. "In contrast, discrete movements like reaching and kicking are behaviors that have reached sophistication in young species, particularly in primates."
Schaal, a robot expert with a deep background in neuroscience who draws inspiration for robot controls from biological models, notes that researchers have historically treated both kinds of movement as fundamentally the same in terms of control -- to say that one is a special form of the other.
Thus specialists studying discrete movement have considered rhythm a subset of discrete movement -- the same thing speeded and repeated -- while behaviorists studying rhythmic movement like walking have considered discrete movement just the same thing slowed and aborted after only a short piece of rhythmic movement.