The one concept of Parkinsonian writing/Parkinsonian movement is that the tremor is only one part (and is often variable - as it is a rest tremor that actually

The one concept of Parkinsonian writing/Parkinsonian movement is that the tremor is only one part (and is often variable - as it is a rest tremor that actually disappears with intention or movement). There are some folks that do have shaky letters but others will not. The other interesting part of it is that the spatial representation of the letters/hand/arm movements, and indeed of limb movements in space, is that it shrinks over time. The term is micrographia. I think the whole idea of how 3D space is represented in the brain is still far from clear, but whoever is able to come up with a good reproducible model would be really onto something (*I would also bet that maybe it's different/distinct from the hippocampal "place" or "grid" cells that won the Mosers the Nobel)..