Considering a Demand and Supply Model of Neuroplasticity: Is the proof in our hands already?

The not-so hidden meaning in this rhetorical question is a reference to the disparate recovery that the upper extremity often experiences vs. the lower extremity, after stroke. First, recovery beyond that which is spontaneously driven be the resolution of an acute hemorrhagic or ischemic event in the brain, requires a reason or stimulus. Personally, I have ascribed a “Demand and Supply” model to the process of neuroplasticity for decades. No functional need, desire, role, stimulus – no recovery. I have suggested that the stimulus comes down to three areas and three only: 1) reinforced learning/reward (extrinsic or intrinsic: food, praise, performance, independence, autonomy, mastery) 2) consequence avoidance (fall, embarrassment, starvation/dehydration, pain, injury, death, bad grade, missed shot, car accident). So, what does this have to do with “our hands”…? Circling back to the opening sentence, we understand that after stroke, the body has a (relative) lower demand on recovery from one arm/hand, than it does on one leg. Due to the natural reach-across compensation that is available and inherent in nearly every ADL, typing/texting, and MRADLs with carrying something…most humans can more completely replicate their pre-stroke life functions with one arm, than they can with one leg. Many have argued that other factors complicate this discussion and I will acknowledge those, for the sake of a comprehensive, albeit brief blog: 1) Number of neurons devoted to the LE vs UE; 2) Amount of recovery (skill) needed for the LE to be functional vs UE to be “chosen” as opportunities arise, not compensated ; 3) Distribution of strokes/lesion location impacting UE/LE; 4) Natural repetitions/demand frequency placed on the LE in recovery.