The GPS of Theseus: Training the body’s navigation system with Parkinson’s

There’s a famous thought experiment called the Ship of Theseus. You replace one plank, then another, then another — until none of the original planks remain. The question is: Is it still the same ship?

In living with Parkinson’s disease and building Brain Storm — a brain-training prototype app for the Apple Vision Pro — I’ve come to think the “ship” metaphor is helpful, but incomplete. I’m not just trying to keep my ship intact; I’m also trying to rebuild my navigation system.

So here’s my upgrade: the GPS of Theseus.

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While the Ship of Theseus is about parts, the GPS of Theseus is about coordinates. It’s about the reference architecture that tells you where you are, where you’re going, and what “on course” even means — especially when the weather turns, the engine sputters, and the map in your head starts to wobble.

Parkinson’s can feel like that: not just stiffness and slowness, but a creeping uncertainty about your body’s relationship to the world. A subtle drift. A loss of calibration. The destination might still matter to you — walk the dog, hug your kid, go to dinner, make it through a meeting — but the “how” starts to degrade. Your movement becomes less like a confident route and more like a negotiation with invisible friction.

Here’s the key idea: The most powerful lever for change isn’t always deep inside the brain. Sometimes it’s at the interface — where the brain meets the body and the world. The boundary. The inputs and outputs. The lived “surface” of the system.

That’s where GPS lives.

A GPS doesn’t fix your engine. It doesn’t repave the roads. It doesn’t change gravity. Rather, it quietly and relentlessly keeps re-anchoring your position. It says: Here you are. Then: Here’s the next turn. And if you drift, it doesn’t shame you; it recalculates.

That’s the heart of the GPS of Theseus: Identity is not a frozen inventory of parts, but the ability to stay oriented while parts are changing.

In the Brain Storm world, we take that seriously — almost literally. We treat the brain-body system like a navigation problem: the internal model (your sense of self, your motor confidence, your predictions about what your body will do next) depends on stable reference points. When those reference points degrade or collapse into pathological synchrony, you don’t just lose movement — you lose separation. Differentiation. The ability to keep sensory channels from blurring into one noisy chorus that drowns out control.

So instead of “How do we push on the hardware?” we ask a different therapeutic question: How do we reconstruct the coordinate system?

And we do it using the most native “ports” you have: sensory and action pathways, especially touch. The fingerpads, for me, are like satellites: simple, reliable network anchors that live on the boundary of the self. They’re always there. They’re honest. They don’t require surgery. They don’t need to cross a blood-brain barrier. They’re a built-in interface.

If you can train the system — repeatedly, gently, with structure — to redifferentiate audio, visual, and tactile streams, and to toggle between single, bi-, and tri-sensory modes, you’re not just treating a symptom. You’re rebuilding the navigation stack.

That’s why I call it the GPS of Theseus. Because what I want isn’t a museum-grade restoration of my original ship. I want a reliable way to steer, day after day, through uncertainty, fatigue, tremor, freezing, and the thousand tiny “Are you kidding me?” moments Parkinson’s likes to throw in my path.

Give us a method to recalculate. Give us coordinates that are true. Give us a resilient navigation system we can train.

And then, plank by plank, step by step, we’ll keep going.

Note: Parkinson’s News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Parkinson’s News Today or its parent company, Bionews, and are intended to spark discussion about issues pertaining to Parkinson’s disease.