(a) Three-dimensional reconstruction of a honeybee brain. The mushroom bodies (MBs) are shown in red. (b) Three-dimensional reconstruction of a honeybee MB in frontal view (vmb) (kindly provided by R. Menzel, Free University of Berlin). Two calyces a lateral (l) and a medial one (m), fuse in a single peduncle (Pe). The somata of the Kenyon cells (KCs), which integrate the MB are located in the calyx bowl. The dendrites of the KC form the calyx which is subdivided in three main regions; the lip, the collar (col) and the basal ring (br). The axons of the KC subdivide and form the α or vertical lobe (vl), the β or medial lobe, and the γ layer (not shown). (c) Multi-modal representation in the MB calyces (kindly provided by Wulfila Gronenberg, University of Arizona). Top: the brain of a honeybee worker Apis mellifera; middle: the brain of a carpenter ant worker Camponotus floridanus; bottom: the brain of a male reproductive C. floridanus. Male ants do not forage and have MBs that are approximately half the size of those of a worker ant. The visual regions medulla (me) and lobula (lo) are shown in red and blue, respectively. The primary olfactory neuropiles, the antennal lobes (al), are shown in yellow; cb, central body; asot, anterior–superior optic tract; aiot, anterior–inferior optic tract; ca, calyces; ml, medial lobe. For each brain, a detail of the sensory afferences at the level of the calyces is shown using the yellow (antennal lobe), red (medulla) and blue (lobula) colour code. Kc1 are the ‘normal’ (‘spiny’) Kenyon cells that give rise to the vertical and medial lobes; Kc2 are the ‘clawed’ Kenyon cells that give rise to a γ layer in the MB lobes.