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Pleasure, Brain Waves and Epilepsy
If a person hears a musical note that they were expecting, within a fraction of a second a pulse of positive electrical potential reaches his or her skull. A similar positive pulse occurs if a person, while viewing a series of pictures, sees for a second time a picture they saw already a few minutes before. At least in this latter style of experiment, sensors all over the skull detect the same pulse, on left and right sides and all the way from front to back; and over half of this wide extent, the pulse height and shape are almost uniform*. The pulse seems to sweep through the brain regardless of the lobes and sulci, regardless of the different functions the parts perform when we think, as if the brain were just cold porridge.
At the other extreme, when ordinary thinking or noticing prompts a neuron to fire, the electric effect runs down just that neuron with hardly any effect on other neurons that may happen to be lying close by. It is the connections that matter i. e. what happens at the synapses at the tips of the axon-branches; two neurons may be physically adjacent but totally unrelated as regards the functions they perform.
We have, in short, a strong contrast: each neuron's own specific electrical effect seems to be wholly insulated from its neighbors, but the electrical pulse from a recognition seems to sweep across regardless of the existence of separate neurons.
The reason for epilepsy being relevant is that in that disability, this contrast breaks down. Necessarily, if two neurons lie alongside each other, an electric pulse in one must have some effect on the other. The effect is usually negligibly small but in people with defective insulation**, some types of brain activity --- unusually intense or unusually rhythmic --- can produce an interaction: a second neuron begins to fire just through being close, regardless of any thought-processes. In fact, in a seizure, swarms of neurons interact in this spatial, irrational way; electrical patterns or waves develop with the same sweeping property as those produced by recognizing a picture. (Or should we call it the cold-porridge property?)
An extra link is as follows: at least on some occasions the act of recognizing yields pleasure, and for some people epilepsy does too. Nowadays most cases of epilepsy can be treated successfully but many prospective patients think twice. For some, the moments of a seizure have a quality that transcends any other sensation they know, an ecstasy comparable with that of visionaries. "I don't want to condemn myself to a monochrome life, I don't want to lose those luminous intimations of the ideal!"
So, how does it work inside the brain? How does the relation between two thoughts produce a spasm of pleasure? Each thought by itself is a pattern of activity in some swarm of neuron-circuits; it seems that two patterns, if they have enough in common, can set up a wave or rhythm of the sweeping, cold-porridge kind. But the "seat of pleasure" is probably deeper in the brain, subcortical, and its "cause" probably as much chemical as electrical*** --- so the source of the sweeping electrical waves still has yet to be worked out.
*** See section on Joshua Fost on the page about previous writers.