April 26, 2018

Debugging my brain

Today was my fifth session with Dr. Nengchun Huang trying to adjust the signals going to my brain to improve my Parkinson's symptoms. I've been doing this every two weeks. Each session has lasted an hour to an hour and a half, as the doctor adjusts the signals and watches my reaction: does my thumb wiggle, my eyes droop or blink rapidly, does my foot twist uncontrollably or steady. Periodically he asks me to do various tasks -- tap my thumb and fingers together like playing castinets; touch my nose and then his finger, back and forth; tap my foot rapidly and evenly.  Periodically we take off the collar and I get up and go out to walk down the hall and back while he watches the regularity of my pace and whether my hand shakes while I'm walking. It's almost always been possible to stop the tremor for a moment by focusing my attention on the body part (like with yoga or tai chi), but usually only for a few seconds. "Don't suppress the tremor", he reminds me often, but it's often reflex.
The ideal is "no symptoms, steady state", and each session has gotten better. For example, the strong impulse to close my eyes is less. My remote control (here wired to the PC) allows me to adjust the overall voltage slightly, and choose between the latest and one of three previously saved programs.

They call this "programming" but it's more like debugging; not modern debugging but the old-fashioned kind, where you're pawing through core dumps and using binary search.

Here's what I think is going on

 The device implanted below my right collarbone communicates wirelessly with the programmer. There are eight contacts one after another on the end of the electrodes skewering my Globus Pallidus Interna on each side, different parts of which are connected to different parts of the brain, controlling movement of my legs and feet and hands and other parts. Each electrode can emit pulses at a given frequency (up to 179 hz) for a periodic burst (I think, the "pulse width") and a given voltage or amperage. Pulses can be monopolar or bipolar  (not sure, but I'm guessing either negative only or negative and positive). The bipolar signals have a narrower effect; the monopolar signals are stronger.
There's no exact map of which parts of the GPi connect to which function of the brain. I think the theory is that the pulses disrupt the beta-rhythms which synchronize the brain function.  Anyway, the Boston Scientific device I have is new, giving the programmer lots of options not possible before.

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