Читать книгу Noises from the Darkroom: The Science and Mystery of the Mind - Guy Claxton - Страница 32

Another important feature of this model is that the total wakefulness of the community – the overall ‘amount’ of activation available to the system at any moment – is finite. If there were no sources of inhibition as well as activation, the octopuses could wake each other up until they were all wide awake at once. Clearly such an eventuality has to be prevented: it would put us in a state of cortical meltdown – a condition of total perceptual and behavioural freak-out. Everything would be ‘On’, but we would be incapable of being appropriate. The beauty of the system of checks and balances built in to the fabric of the octopus colony is that it becomes, of its very nature, selective and integrative. The colony as a whole has to choose and moderate amongst what is going on.

This is not to say that the total level of activation is always fixed. If you looked down from your helicopter and counted the pink bodies, there would not always be exactly the same number. Sometimes the total might be a bit greater, sometimes a bit less, but the important point is that the total is relatively fixed, and is certainly finite. It cannot explode, though it may vary somewhat as a reflection of the overall state of ‘alertness’ of the system.

In fact, though, there is a very important source of variability in the effective amount of energy that the system has at its disposal, independent of variations in the total energy available. Imagine that, when a particular gang of octopuses, A, is awake, one of its ‘jobs’ is to send a constant low-level tickle (or massage) to a variety of other gangs or individuals, B, C and so on. In addition, suppose that A is able to stay awake for long periods of time. These continuous ‘trickles’ of excitation and inhibition will make a network with one set of connections respond as if it were a network with a different pattern of strengths. The crucial difference, however, between the effect of priming, and the long-term change in the strengths of the connections, is that, in the former case, it is possible for the priming overlay to be removed. If A were turned off, even for just a few moments, there would be an instantaneous, apparently ‘magical’ reorganization, perhaps a re-prioritization, of the brain system as a whole. What had always been ‘at the back of one’s mind’, or ‘on the tip of one’s tongue’, now would no longer be there, or would stand out with unfamiliar clarity.

And in this hypothetical situation there would be another interesting effect as well. While unit A has been ‘on’, it has not only been keeping particular other units or groups of units on a hair trigger; it has in so doing been keeping tied up some proportion, perhaps a significant proportion, of the total activation permitted in the brain. If there is only so much energy available at any time, then if 10 per cent of it has to be dedicated to certain locations to keep them primed, there is less available – less ‘free energy’, we might say – to underwrite the activity of the rest of the system. And the less free energy there is, the more crude or stereotyped we might imagine the response of the system to be. Only those octopuses with the lowest thresholds, and the biggest and most numerous inputs, get woken up. (This option, for the brain to change its way of operating by tying up some of its total pool of activity, will become very important later when we try to explain the phenomena of mystical experience.)