Fig. 6.

Network motifs that are most frequently encountered in micro-volumes. A-C: Dense overlapping regulon motif. A: Segment of one “primary” presynaptic element (turquoise; varicose neurite) which contacts five postsynaptic elements (dendritiform neurites) at two synapses. B: Same configuration of pre- and postsynaptic elements as in A; several other “secondary” presynaptic elements (green) which form synapses with the same dendrites as the primary axon are shown. C: schematic representation of this network motif. D-H: Feed forward motif. D, E, F: 3D digital models and schematic modelof segments of three varicose neurites which form predominantly presynaptic contacts (terminal axons). The blue element has a thin branch that is postsynaptic to the light-green element (white arrow in D-F). Shown are also the dendritiform postsynaptic neurites that are postsynaptic to both green and blue varicose neurites. G, H: EM sections at levels shown by lines in panel D. G represents top level and shows the synapse between pre-/postsynaptic element (blue) and presynaptic element (green; arrow).

Bar: 1µm