14 December 2008

Riding a bike

I was 5 when I learned to ride a bike. I remember the place - a thin strip of asphalt surrounded by very green grass, just beside a small patch of forest - where I first managed to ride it for a stretch without dad holding it steady and without falling over. Imagine my brain at the time. Imagine two pulsating groups of active neurons in each prefrontal cortex, slowly circling each other. One, oscillating slowly, projecting to the motor cortex right at the top of my head and down between the lobes, driving the oscillating contractions of leg and foot on the pedal. The other, pulsating a seemingly patternless pattern to the motor cortex below the upper sides of the skull, constantly adjusting the handle bar with a cramped grip, keeping the whole circus upright. Both groups, closely connected to eachother and to their mirror images in the opposite lobe, receiving a constant barrage of input: sight from the back of the brain and the colliculus, balance from the inner ear, kinetics from the spinal cord. Both groups constantly adjusting their output to maximize the flow of reinforcing dopamine from their respective midbrains. And that's why I remember it so well, that moment when the groups finally got the output right, for a time, and were showered with dopamine as all regions of the brain reported success. The dopamine reinforced them, and with them every other process that was active in my frontal lobes at the time - the location, the weather, the color of the grass.

After that of course, I've kept on biking, for years and years and years, milking those two groups for all the dopamine they were worth, until they were neat and trimmed and refined to a point where almost all the oscillation and rotation and complex feedback loops have been moved over to small, dedicated central pattern generators in my motor cortex and spinal cord.
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