The brain is a statistical computer. Its neurons are richly connected by synapses, each of which holds a probability that a pulse from one neuron will trigger the other. Everything we know, it is claimed, has been acquired and is stored as innumerable synaptic firing probabilities.
This cannot be the whole truth. Nerves fire in milliseconds; but it can take many weeks or months to learn a skill, see an argument or change our mind. We all waste years of life nursing unrealistic hopes, recovering from emotional set-backs, coming to terms with limitations or advancing age, or abandoning foolish compulsions or delusions. Why is mental change so slow? Daedalus points out that nerves are hollow; they are filled with fluid axoplasm. This contains not merely the ions of nerve action, but cell nutrients, enzymes, and so on. These diffuse slowly along the nerve, typically at a few millimetres a day. (The rabies virus makes its relentless, deadly passage from bite to brain by diffusing up the nerves at this sort of rate.) If the firing probability of a synapse can be altered only by the diffusion of some key component down the axon, the slow pace of human mental change would be explained.
Daedalus now plans to speed it up. A blow on the head is popularly supposed to shake one's ideas up; and shock could well help to stir the cerebral axoplasm. But ultrasonics seems more controllable. An ultrasonic cleaning bath works by very small-scale stirring indeed. DREADCO's cunning new ‘Brain-cleaner’ launches a highly asymmetric, ultrasonic waveform into the skull. Axoplasm has a non-newtonian viscosity. The sharp leading edge of each cycle shifts it abruptly one way, but the reduced shear of its gentler trailing edge does not reverse the shift exactly. So the axoplasm convects strongly, updating the synaptic probabilities in minutes rather than months.
Regular brain-cleaning will save us all years of life. Emotional traumas, from failed love-affairs to bereavements and sackings, will be swiftly put behind us. The economic cycle will speed up or even be damped out, as economists and business tycoons no longer lag behind the changing reality. Generals may at last cease to prepare for the previous war. Psychoanalysts will go bankrupt in droves: their patients will be transformed after mere days on the couch. Technological advance will become even more breathless, and the world of fashion will change with dizzying speed.
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Crystallography Reports (2011)
The Journal of Chemical Physics (2001)