"Use it or Lose It"

Neuroplasticity principle number one.

This phrase has been flung into the air throughout our ages. When you wanted to get faster at the timed mile your coach had you do running butt-kicks, high knees, bounding running to build your muscle strength and speed. When you wanted to learn to play the piano, guitar or ukulele and you finally got the chord timed with the other hand's trill, and then 3 months later tried it and the perfect timing of both hands was lost. When there are so many toys from neighborhood kids, aunts and uncles, and grandparents and you watch what your kid plays with in one week and swiftly donate the rest to Salvation Army...out of sight, out of mind. When you joined ToastMasters to overcome your fear of public speaking and felt more confident for 15 years of your career. This phrase is also physiologically based in our body composition of fat and lean muscle mass. And our mind's availability to coordinate a movement or series of movements for skill acquisition and automaticity. Big phrases...breaking it down to stay together here.

Let's take playing the piano as an example of skill acquisition. You might have broken down a song or a scales practice with reading the notes on the staff, then moving your fingers with ONE hand, then repeat the process with the other hand, before putting it together and simultaneously playing with both hands. Your mind first had to be introduced to the concept of reading sheet music, then matching the order of the keys on the piano to the notes on the music staff, then linking the reading of music to the pressing of the indicated piano key with your finger. As we repeat this process, "use it", we are familiarizing our brains with the association of a pictorial note on a music staff to the finger pressing the piano key. The meaning of one to the other is building. Our focus can relax and our accuracy persists. This is skill acquisition. Fast-forward 1000 practice sessions and you are answering your family member's question, while looking over your shoulder at them, music book closed, and your fingers are flying thru the music accurately, in sync with timing of your right and left hand to play beautiful sounding music. The skill has been acquired and the capability to perform accurately, at a faster speed, and with less mental attention to the actual task of playing piano has grown in complexity; almost to the point of minimal attention and motor memory gracing your fingers across the piano keys. There is an automaticity of movement occuring as less and less mental attention is acquired to perform the skill. Let's look at negotiating stairs as an example of automaticity.

Watching a toddler start crawling up stairs, and crawling down stairs backwards is early navigation of a task requiring strength, balance, and range of motion beyond the toddler's years.

Then watching an adult running up/down stairs while carrying her work bag across her body, water bottle in one hand, and shoes in the other hand moving at the speed of lightening. As our bodies and brains develop, our nerve connections grow stronger and larger to improve the accuracy of our movement.

As balance improves to standing upright our bodies and brain adapt and develop strengthened neural connections for weight shifting quickly, running, and adapting to added weight on the body and objects being held in hands. Even if we miss a step, we can often recover mid stride! The accuracy of our neural connections and the ability to deviate to a different connected path to regain our balance is intricate and strong. The progression of a skill from acquiring the ability to walk upright up and down stairs with holding onto a parent's hand, then a rail, to without a rail, to quickening the speed of alternating feet on stairs, to carrying objects, and reacting to a mis-step are all examples of skill acquisition over and over again, to the automaticity of the movement. I don't have to think about lifting each foot and deciding where to place it on the stairs, nor do I have to stare at my feet to ensure my accuracy. This movement is seemingly just occurring, while my mind is on my to-do list or talking on my phone simultaneously. The automaticity of the movement is achieved when conscious awareness is minimally required, while performance and accuracy are maintained. The opposite progression occurs sometimes with aging. All of a sudden flying up and down the steps is leading to errors, sometimes drastic like a fall with an injury. Mental attention is being demanded back to the task, we seek our eyes on our feet to verify that we accurately placed our foot on the step fully to avoid a slip, we slow down the sequence to improve our accuracy, and grab a rail to decrease the balance demand on our legs. The process happens both ways, skill acquisition turns to automatic movement, and automatic movement degrades to the skill re-acquisition stage.

Back to the research, 'cus I'm a nerd, and a scientist.

Kliem, JA and Jones, TA (2008). Principles of Experience-Dependent Neural Plasticity: Implications for Rehabilitation After Brain Damage. Jounral of Speech, Language, and Hearing Research,51, S225-S239.

The "Use it or Lose it" principle has two principle impacts:

1) "Failing to engage a brain system due to lack of use may lead to further degradation of function"

2) "Functional recovery may be supported, at least in part, by shifting novel function to residual brain mass."

I read two things here: function is lost when we do not engage our system AND healthy brain tissue can adapt to relearn tasks that were lost by injury to brain tissue. There is an experiential component and a physiologic component that we have the power to tap into to improve our brain and body function. I am going to throw in the term homunculus. We've stepped into graduate and collegiate level learning, hang onto your pen and pencil!

The homunculus is a pictorial description of the area of the brain that receives information about what our sensations from our skin, joints, muscles, and viscera are signaling and the area of the brain that send signals via nerves to our muscles to move certain regions of our body. Meet Homunculus:

Homunculus shows us brain "truths":

1) The area of the brain affected by a lesion in the motor cortex, results in a loss of the ability to elicit movements in adjacent regions of the cortex.

Looking at the first homunculus picture with the brain mapping in pink: If a stroke impacted the brain area that controls movement of the thumb and index finger, the surrounding areas may also be affected: control of the middle, ring, and pinky finger, as well as, the ability to control the wrist and elbow.

2) This loss is prevented and functional reorganization is promoted by behavioral experiences: i.e. rehabilitative training.

A common physical and occupational therapy approach is constraint-induced therapy. Let's say your left hand is not moving as well as your right as a result of a brain injury. A therapy exercise to increase your coordination and movement would be completed with your left hand, while your right hand is constrained in a towel, glove, or holding a ball. The brain would select to use the right hand, because it is moving better, but with the constraint on the right side, the brain will work with your left hand to problem-solve and strengthen the connections from the brain, to the nerves, to the muscles. Research has shown that constraint plus training is associated with a reduction in the tissue loss in the damaged striatum. By participating in specific training you can affect the anatomy of your brain! Change your experience or behavior and you can change your brain. Power!

I have to acknowledge the less shiny side of the coin. Overuse can further impair function. The left hand, from our prior example, if over-used may show a slower recovery or impair recovery of function. If this isn't a slam-dunk reason to work with a Doctor of Physical Therapy or a Doctor of Occupational Therapy, not sure what else will build confidence in working with a health care practitioner. Physical Therapists are trained on the relevance of timing and intensity scaling of interventions to optimize their patients outcomes and recovery. We geek out on this and our success is your success. Work with a professional to maximize your recovery and use of your time and resources.

Animal, including human, models are used to research how our brains and bodies work. Here's some highlights from research conducted with regards to our homunculus (and other brain areas) and neuroplasticity. The discussed articles are all referenced in the Kleim and Jones article for further reading and geeking out.

In 1965, Hubel and Wiesel published results from deprivation of light in kittens. One of our sensory systems is our eyes: vision. Kittens are representative of a young brain with a lot of neuroplasticity potential (see the 10 Principles of Neuroplasticity post). The kittens' brains demonstrated a decrease in the number of neurons in the visual cortex that responded to light. An anatomical change of less neurons present in the area of the brain that detects and responds to light. The experiential or behavioral change of light being deprived led to an anatomical change. Your behavior effects your anatomy. You hold powerful potential. How will you handle it?

In 1969, Fifkova published results on an adult brain, demonstrating a reduction in neuronal responses to light was accompanied by decrease in synapse number. Now we link a behavioral change to a decrease in physiologic function AND a change in anatomy. You hold even more powerful potential in your behavior and experiences you choose to participate in.

In 1984, Merzenich et al. looked at the somatosensory cortex (homunculus pictorial representation of sensation on the left, in purple) in owl monkeys. A digit (finger) was removed. Two to 9 months later the corresponding cortical representation (the area of the brain that was responsible for that lost digit), now was responsive to adjacent digits and skin surfaces of the palm. The brain adapted to a change in anatomy, leading to a change in behavior, which changed the physiology of how the brain was organized for its function. You lose something significant, and your brain can adapt and grow to improve function.

In 1987, Reale, Brugge, and Chan looked at auditory deprivation. A different sensory system. Loss of sound representation led to a decrease in synapse number in the cortex. We are back to a change in behavior leading to a change in physiology and anatomy.

In 1998, Pascual, Hervias, Toha, Valero, and Figueroa researched developing rat brains. When the rats' movements were restricted, Purkinje neurons in the cerebellum developed poorly.

Purkinje neurons are defined by the NIH as having the ability to integrate large amounts of information and learn by remodeling their dendrites. Dendrites release a neurotransmitter GABA, which inhibits neurons, thereby reducing nerve impulses to regulate and coordinate movements. It is our fine-tuning system.

When movement is restricted, our fine-tuning system develops poorly. Am I driving the point home yet, when our experience or behavior is limited, our ability to coordinate and move our body well diminishes. If an event occurs that we can't change, after-the-fact, we better hop on the experience and behavior train to preserve, protect, and rebuild our ability to coordinate and move our bodies. The only other option is to lose it and continue to lose more. Enough has been lost. Enough.

1996, Sadato et al. researched blind subjects and demonstrated activation of the visual cortical areas during tactile tasks, such as Braille reading. An area of the brain that was not utilized for its original function, seeing, CAN change and adapt to be active in a substitutive or complimentary task such as touch and feeling for language. We have research supporting so many brain areas adapting and changing based on the type of sensory stimulus it is receiving vs. what it has lost or never had. A change in the anatomy or in our sensory experience leads to a change in the physiologic organization of our brain.

In 2001, Finney, Fine, and Dobkins demonstrated in deaf subjects that the area of the brain responsible for auditory signal processing was activated by visual stimuli. When one sensory system is lost, another sensory system gains priority and can remap the brain. The brain can change and adapt, can the personality, will, grit, and perseverance of the personality attached to that brain rise to the same potential?

Potential...we have it. How far can we take it? No one can tell us, statistics can throw some probability at us. But unless you put your body and brain into action, you will never grow to know your potential. Neurologic rehabilitation thrives on this unknown maximum potential and the research to support the physiologic and anatomical changes that occur when intensity, specificity, timing, and repetition are skillfully applied. Your neurologic physical therapist is waiting to unlock your potential.