Are these complexes pretty much the same for everybody?
Are corresponding ones found in corresponding places in differ-
ent people's brains?
Do they overlap in the same way in everybody's brain?Philosophically, the most important question of all is this: What would
the existence of modules-for instance, a grandmother module-tell us?
Would this give us any insight into the phenomenon of our own conscious-
ness? Or would it still leave us as much in the dark about what conscious-
ness is, as does knowledge that a brain is built out of neurons and glia? As
you might guess from reading the Ant Fugue, my feeling is that it would go
a long way towards giving us an understanding of the phenomenon of
consciousness. The crucial step that needs to be taken is from a low-
level-neuron-by-neuron-description of the state of a brain, to a high-
level-module-by-module-description of the same state of the same brain.
Or, to revert to the suggestive terminology of the Ant Fugue, we want to
shift the description of the brain state from the signal level to the symbol
level.Active SymbolsLet us from now on refer to these hypothetical neural complexes, neural
modules, neural packets, neural networks, multineuron units-call them
what you will, whether they come in the form of pancakes, garden rakes,
rattlesnakes, snowflakes, or even ripples on lakes-as symbols. A description
of a brain state in terms of symbols was alluded to in the Dialogue. What
would such a description be like? What kinds of concepts is it reasonable to
think actually might be "symbolized"? What kinds of interrelations would
symbols have? And what insights would this whole picture provide into
consciousness?
The first thing to emphasize is that symbols can be either dormant, or
awake (activated). An active symbol is one which has been triggered-that is,
one in which a threshold number of neurons have been caused to fire by
stimuli coming from outside. Since a symbol can be triggered in many
different ways, it can act in many different ways when awakened. This
suggests that we should think of a symbol not as a fixed entity, but as a
variable entity. Therefore it would not suffice to describe a brain state by
saying "Symbols A, B, ... , N are all active"; rather, we would have to supply
in addition a set of parameters for each active symbol, characterizing some
aspects of the symbol's internal workings. It is an interesting question
whether in each symbol there are certain core neurons, which invariably
fire when the symbol is activated. If such a core set of neurons exists, we
might refer to it as the "invariant core" of the symbol. It is tempting to
assume that each time you think of, say, a waterfall, some fixed neural
process is repeated, without doubt embellished in different ways depend-
ing on the context, but reliably occurring. However, it is not clear that this
must be so.Brains and Thoughts 349