title: Neurons innervating the lamina in the butterfly, Papilio xuthus.
abstract: The butterfly Papilio xuthus has compound eyes with three types of ommatidia. Each type houses nine spectrally heterogeneous photoreceptors (R1-R9) that are divided into six spectral classes: ultraviolet, violet, blue, green, red, and broad-band. Analysis of color discrimination has shown that P. xuthus uses the ultraviolet, blue, green, and red receptors for foraging. The ultraviolet and blue receptors are long visual fibers terminating in the medulla, whereas the green and red receptors are short visual fibers terminating in the lamina. This suggests that processing of wavelength information begins in the lamina in P. xuthus, unlike in flies. To establish the anatomical basis of color discrimination mechanisms, we examined neurons innervating the lamina by injecting neurobiotin into this neuropil. We found that in addition to photoreceptors and lamina monopolar cells, three distinct groups of cells project fibers into the lamina. Their cell bodies are located (1) at the anterior rim of the medulla, (2) between the proximal surface of the medulla and lobula plate, and (3) in the medulla cell body rind. Neurobiotin injection also labeled distinct terminals in medulla layers 1, 2, 3, 4 and 5. Terminals in layer 4 belong to the long visual fibers (R1, 2 and 9), while arbors in layers 1, 2 and 3 probably correspond to terminals of three subtypes of lamina monopolar cells, respectively. Immunocytochemistry coupled with neurobiotin injection revealed their transmitter candidates; neurons in (1) and a subset of neurons in (2) are immunoreactive to anti-serotonin and anti-γ-aminobutyric acid, respectively.
authors: Laboratory of Neuroethology, Sokendai-Hayama (The Graduate University for Advanced Studies), Shonan Village, Hayama, Kanagawa, 240-0193, Japan.
authors: Yoshitaka
authors: Y
authors: Hamanaka
authors: Hiromichi
authors: H
authors: Shibasaki
authors: Michiyo
authors: M
authors: Kinoshita
authors: Kentaro
authors: K
authors: Arikawa
mesh_terms: D000818:Animals; D001710:Biotin / Q000008:administration & dosage / Q000031:analogs & derivatives; D002080:Butterflies / Q000378:metabolism / Q000502:physiology*; D003118:Color Perception; D054910:Compound Eye, Arthropod / Q000294:innervation*; D004192:Discrimination, Psychological; D005260:Female; D005455:Fluorescent Antibody Technique; D059330:GABAergic Neurons / Q000378:metabolism / Q000502:physiology; D007267:Injections; D008297:Male; D018613:Microscopy, Confocal; D056347:Neuroanatomical Tract-Tracing Techniques; D056325:Neuronal Tract-Tracers / Q000008:administration & dosage; D019581:Neuropil / Q000378:metabolism / Q000502:physiology; D010641:Phenotype; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism / Q000502:physiology*; D059326:Serotonergic Neurons / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism / Q000502:physiology; D014795:Visual Pathways / Q000378:metabolism / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D056325:Neuronal Tract-Tracers; C070614:neurobiotin; D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D001710:Biotin