Mushroom Body Evolution

Mushroom Body Evolution - Figure 4

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Figure 4: Mushroom bodies vary in shape. Specific parts of their structure are accentuated or reduced, depending on the taxon. These structural differences possibly reflect the different roles that mushroom bodies play in different taxa in sensory processing, multimodal integration, motor control, and learning and memory. The calyces, for example, receive inputs from the antennal lobes and are proportionately larger in taxa, such as the cockroach (A), where olfactory inputs are predominant. In anosmic diving beetles (G), the calyces are absent, as are the antennal lobes. But the medial lobes are still present, suggesting that these play a role in multimodal integration even in the absence of olfactory inputs. In butterflies and moths (F), the lobes are often divided into many separate components. The significance of this is not yet known.

In this figure, the organization of globuli cell groups (blue areas), calyces (red), pedunculi and medial lobes (yellow), and vertical lobes (mauve) are compared in odorant-sensitive (A-F) and anosmic (G-I) insects. A. Periplaneta americana (cockroach; Blattoidea); B. Barytettix psolus (horse lubber, Acrididae); C. Acheta domesticus (cricket; Acrididae); D. Labidura riparia (earwig; Dermaptera); E. Calosoma scrutator (caterpillar hunter beetle; Coleoptera); F. Huebnerniana trifolii (cinnabar moth; Lepidoptera); G. Dytiscus marginalis (diving beetle; Coleoptera); H. Notonecta undulata (backswimmer; Hemiptera); I. Argia sp. (damselfly; Odonata). In some species, the calyx is divided into inner, middle, and outer components, i, m, o); V, M, F, R, vertical, medial, frontal, and recurrent lobes (in some species, lobe subdivisions represent inner, middle, and outer calyces); S, spur. sat, satellite neuropil. Scale bars each equal 100 µm.

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