NERVE LENGTH AND VOLUME IN SYNAPTIC VS DIFFUSION NEUROTRANSMISSION - A MODEL

NON-SYNAPTIC diffusion neurotransmission (NDN) may be an important fac tor in brain space and energy conservation, especially within cell ass emblies and for mass sustained functions. We have illustrated the extr eme cases of total synaptic and total ND neurotransmission for the pur pose of noting the differences between the two. For these modeling stu dies, in which we assume assemblies of 1000 to 100 000 cells supplied by at least one fiber and a single synapse from each of the other cell s, each cell assembly would have approximately 200 m to 8000 km of ner ve fibers more than when innervated by diffusion. For coeruleo-cortica l synaptic innervation, linking each to a common origin (the locus coe ruelus), the fiber lengths are 38 cm (1000 cells) to 170 m (100 000 ce lls), It is likely, however, that neuronal arrays include both `wirele ss' (NDN) as well as synaptic intercellular communication systems.