On the nested hierarchical organization of CNS: Basic characteristics of neuronal molecular networks

It has been suggested that the Central Nervous System (CNS) is built as a "nested system of networks of networks" structured according to hierarchical principles. Thus, it is possible to recognize networks at multiple scales (miniaturisation principle) moving top-down from neuronal to molecular networks. Such a nested organization of the CNS leads to the problem how circulation and integration of information at different levels of miniaturisation (i.e., macro-scale, meso-scale and micro-scale) take place. We suggest that local circuits are the highly specialised meso-scale level capable of functionally interconnecting macrowith micro-scale level. Furthermore, it is suggested that the same modes for communication (Wiring and Volume Transmission) are in operation at various miniaturisation levels. This indicates a sort of "fractal organization" of the CNS. Detailed analysis of molecular networks is discussed. In particular, receptor-receptor interactions are examined as an important input to horizontal molecular networks located at plasma membrane level.