title: Polarization-sensitive descending neurons in the locust: connecting the brain to thoracic ganglia.
abstract: Many animal species, in particular insects, exploit the E-vector pattern of the blue sky for sun compass navigation. Like other insects, locusts detect dorsal polarized light via photoreceptors in a specialized dorsal rim area of the compound eye. Polarized light information is transmitted through several processing stages to the central complex, a brain area involved in the control of goal-directed orientation behavior. To investigate how polarized light information is transmitted to thoracic motor circuits, we studied the responses of locust descending neurons to polarized light. Three sets of polarization-sensitive descending neurons were characterized through intracellular recordings from axonal fibers in the neck connectives combined with single-cell dye injections. Two descending neurons from the brain, one with ipsilaterally and the second with contralaterally descending axon, are likely to bridge the gap between polarization-sensitive neurons in the brain and thoracic motor centers. In both neurons, E-vector tuning changed linearly with daytime, suggesting that they signal time-compensated spatial directions, an important prerequisite for navigation using celestial signals. The third type connects the suboesophageal ganglion with the prothoracic ganglion. It showed no evidence for time compensation in E-vector tuning and might play a role in flight stabilization and control of head movements.
authors.affiliation: Fachbereich Biologie, Tierphysiologie, Philipps-Universität Marburg, D-35032 Marburg, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Träger
authors.forename: Uwe
authors.initials: U
authors.lastname: Homberg
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001921:Brain / Q000166:cytology*; D004594:Electrophysiology; D019835:FMRFamide / Q000378:metabolism; D007839:Functional Laterality; D005728:Ganglia, Sympathetic / Q000166:cytology*; D006040:Goals; D006110:Grasshoppers; D019476:Insect Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D009475:Neurons, Afferent / Q000145:classification / Q000502:physiology*; D027361:Organic Anion Transporters / Q000378:metabolism; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012701:Serotonin / Q000378:metabolism; D013223:Statistics as Topic; D027981:Symporters / Q000378:metabolism; D015320:Tachykinins / Q000378:metabolism
chemical_list: D019476:Insect Proteins; D027361:Organic Anion Transporters; D027981:Symporters; D015320:Tachykinins; C421224:sialic acid transport proteins; C068632:locustatachykinin III protein, insect; D012701:Serotonin; D019835:FMRFamide