Fig. 1.

a Horizontal reconstruction of the PDF-expressing neuron system of the cockroach Leucophaea maderae in the supraesophageal ganglion (AMe accessory medulla, aPDFMe anterior group of PDF-expressing neurons, AOC anterior optic commissure, dPDFLa dorsal group of PDF-expressing lamina neurons, La lamina, Me medulla, pPDFMe posterior group of PDF-expressing medulla neurons, POC posterior optic commissure, POTu posterior optic tubercle). Bar 500 μm. b Representation of the neuron groups of the accessory medulla (AMe) including the PDF-expressing medulla neurons (PDFMe, colored) as derived from morphological and immunohistological analyses (DFVNe distal group of frontoventral neurons, MFVNe medial group of frontoventral neurons, MNe medial neurons, VNe ventral neurons, VMNe ventromedial neurons, VPNe ventroposterior neurons). Although the numbers of gray circles do not reflect the actual group sizes, the numbers of colored circles represent the rounded mean numbers of the respective PDFMe neurons according to previous work. Large (purple, plus one largest) and medium-sized (dark blue) PDFMe belong to the VNe, whereas small PDFMe (light blue) appear to belong to the DFVNe neurons. Previous work has suggested that two large and one medium-sized PDFMe together with one unspecified VNe (C) project to the contralateral AMe to provide a mutual pacemaker coupling input. The unspecified VNe is suggested to express either an FMRFamide-related peptide or orcokinin (di distal, do dorsal)