Re: Where does motor memory come from, specifically for karate strikes?

Good question! There is no such thing as "muscle memory," because your muscles 
are just composed of fibers that contract (get smaller) and relax.  The 
actual "memory functions" are in the brain.  

The general coordination for muscles is in a very old part of our brain that 
humans retained from our anmal ancestors, called the cerebellum. The cerebellum 
in most lower animal species simply functions "automatically," through reflex 
action.

Human beings have more precise ability to control our muscles, in a structure 
in the higher brain, called the cerebrum, and the structure area is known as 
the "motor cortex" area. There are specific areas in the motor cortex for the 
various muscles that humans can voluntarily control, such as arms, hands, 
fingers, legs, feet, toes, etc.  

As you practice with your voluntary muscles, your motor cortex makes new nerve 
connections for that area.  The more you practice, the more nerve connections 
there are.  Basically, it is like having a "dirt road" that, with practice, 
becomes a smoothly paved highway.  Your brain learns that it will continue to 
get stimulation to the same area, so the brain makes the connections easier for 
the stimulation to be processed.  That is why any voluntary motor movements are 
difficult at first, and then become smoother, more precise, and easier to do, 
after many repetitions.  

How long does this take to acquire?  That depends on how much a person 
practices and repeats the same movements with the same voluntary muscles.  It 
also depends on how well the brain itself can make the new connections, and 
whether the neurotransmitter chemicals in the brain are properly functioning, 
because the chemicals are the way the electrical signals of the nerves go from 
one nerve to the other, in the brain pathways. Of course it also depends on 
whether the brain itself is healthy, and functioning normally. If the brain 
structure and brain chemicals are working normally, then a new voluntary muscle 
skill depends on frequent and CONSISTENT repetition, and that is very 
important.  You will learn a new skill much faster if you repeat it every day, 
and you will learn much slower if you try to do a lot of repetitions with 
several days' of gaps in between the practices.  The brain must be sure that 
the repetitions are consistent, such as every day, before the brain will 
effectively place the movement information into permanent memory, and make new 
connections. So, even a moderate amount of daily repeats will provide more 
actual skill than if a person does a lot of repeats only on weekends.

There is no overall answer as to precisely "how long" it will take for any 
specific individual to learn a specific voluntary muscle movement.  People are 
different, and some people already have done similar types of movements with 
prior memories stored in their motor cortex, while others have not.

How long do the enhanced pathways last?  As long as you continue to use those 
pathways. If you stop doing the memorized movement patterns, the brain will 
retain the "highway," but that "highway" will get potholes, and will become 
overgrown with weeds, if you don't use the highway. Actually, the brain keeps 
the connections, and the pathways, for a long period of time, many years in 
fact, but if you don't use the specific pathways for a long time, the brain 
will assume that you have abandoned that type of movement, and it will not make 
that movement path a top priority anymore.  After that, if you do go back to 
the same movements again, it will require more practice to remind the motor 
cortex of the movement patterns.  But the "reminding" will take much less time 
than it did when you first learned the movement patterns. Clearing the weeds 
from a highway is much faster than building the highway.

The brain is a fascinating organ of the body. To see a picture of the various 
areas of the brain, with descriptions, go to the following webpage, and if you 
do have time, read all of the rest of the sections on this website below, for 
even more fascinating information...

M.M.M. Brain Tour: Large Scale Features
Address: http://suhep.phy.syr.edu/courses/modules/MM/Biology/bio_large.html

Thank you for using the Mad Scientist network, and send in more questions. And 
may you have good times in your karate activities!