(a,b) Upper right schematics show in blue the locations of the brain (a; frontal head view) and VNC (b; top view of head and thorax) within a fly body. Lower right schematics show the general anatomy of a DN, including a soma in the brain (red dotted circle) (a) and processes in the VNC (b). Fly cartoons from Wikimedia Commons. (c) Schematic showing the approximate location of DN somas according to the naming scheme used in Namiki et al. (2018). For clarity, the left-hand illustration shows locations of each soma group on only one side of the bilaterally symmetric brain. DNx somas (not shown) are outside the brain. (d) Schematic showing the approximate location of VNC neuropils by which DNs were categorized systematically in Cheong et al. (2024). As in (b), the dorsal/ventral views often show neuropil location on only one side of the bilaterally symmetric VNC. ‘xn’ DN types (not shown) innervate multiple neuropils. (e) Bar plot showing the number of DN types in each soma- location category. Coloured bars indicate the number of types for which there exist at least 2 highly specific (‘A’) lines (teal), 1 highly specific line (dark blue), only non-specific or inconsistently expressing lines (‘B’ or ‘C’) (light blue), or no split-Gal4 lines (grey). DN types with no corresponding split-Gal4 lines are further separated by whether they were ever identified from light microscopy images in a very broadly expressing Gal4 line (dark grey) or identified only from electron microscopy images (light grey). (f) Bar plot showing the number of DN types innervating each VNC neuropil. As in (c), coloured bars indicate the number of types for which there exist a given number of specific or non-specific lines.

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Morphology of descending neurons identified in Namiki et al. (2018) and in the present study.

Images of neurons have been manually segmented (see Methods for details). Asterisks indicate images showing two or more neurons of the same type (generally both instances of a bilateral pair).

Maximum-intensity projections showing DNp17 lines representative of ‘A’, ‘B+’, ‘B’, and ‘C’ scores for cleanliness/consistency.

Colour indicates depth in the Z axis (violet→pink = anterior→posterior in the brain and ventral→dorsal for the VNC).