It has been proposed that volumes of neural tissue may represent impor
tant processing elements. This viewpoint suggests one way that populat
ions of synaptic elements cooperate to implement important computation
al capacities. I extend this view by proposing a set of computational
functions for the extracellular space shared by a local population of
synapses. The critical hypothesis is the existence of a hypothetical '
fluid' resource present outside synapses that must be internalized in
order for a synapse to Function. I outline some of the consequences of
assuming that such a resource is in limited supply on short time scal
es.