Extended Data Fig. 8: Subcellular structures support local and nonlocal connectivity, and RIA and AIB processes exhibit synaptic compartmentalization.
From: A multi-scale brain map derived from whole-brain volumetric reconstructions
a, b, Volumetric rendering of RIAL and its synapses (cuboids) coloured by synaptic polarity (a) or intra-/inter-cluster (b). The synaptic input and output segments in a correspond to changes in neighbourhood composition in b. Changes in RIA neighbourhood correspond to the three neurite segments (nV, nD and loop) which exhibit independent calcium dynamics that encode head movement46. c, d, AIB processes change neighbourhood at the dorsal midline18. The ipsilateral segment (†) of the AIB process is surrounded by cells in the taxis cluster, whereas the contralateral segment (††) makes contact with cells in every other cluster. c, AIB-process segments alternate between synaptic inputs on the ipsilateral side and synaptic outputs on the contralateral side. d, The alternating synaptic inputs and outputs correspond to a change in neighbourhood occurring at the dorsal midline. e–h, Flattened protrusions link processes to adjacent cells in adjacent clusters. e, The flattened protrusion strategy as demonstrated by RIM processes (♦). f, The RMDV processes show how flattened protrusions are used to locally expand synaptic polarity. On the contralateral side, the main process trajectory is postsynaptic whereas the contralateral protrusion is presynaptic. Both AVA (g) and SAAV (h) neurons exhibit flattened protrusions that appear to turn into small branches. The small AVA branch extends into a neighbourhood of cells from a different cluster (*). SAAV ipsilateral branches receive synaptic inputs, whereas its main process trajectory on the contralateral side is mostly presynaptic. Spine-like features extend from RMEV/D processes to cells in a different cluster. i, j, Two longer RMED extensions (i) and three shorter RMEV spine-like extensions (j) are postsynaptic to the sublateral cluster. In all images, the pharynx is shown for spatial reference. R, right; A, anterior; V, ventral. Note that for visual clarity, synapses have been offset from the cell process. k, Schematic of neighbourhood changes of selected cells (labelled in the colour of the cluster assignment). P, proximal and D, distal to cell body. Each trajectory is scaled to the length of the reconstructed left L4 process. Black boxes denote sections in which the process makes contact with at least two clusters.
