@article{HensgenEnglandHombergetal.2021,
  author    = {Hensgen, Ronja and England, Laura and Homberg, Uwe and Pfeiffer, Keram},
  title     = {Neuroarchitecture of the central complex in the brain of the honeybee: Neuronal cell types},
  series = {Journal of Comparative Neurology},
  volume    = {529},
  journal   = {Journal of Comparative Neurology},
  doi       = {10.1002/cne.24941},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-215566},
  pages     = {159-186},
  year      = {2021},
  abstract  = {The central complex (CX) in the insect brain is a higher order integration center that controls a number of behaviors, most prominently goal directed locomotion. The CX comprises the protocerebral bridge (PB), the upper division of the central body (CBU), the lower division of the central body (CBL), and the paired noduli (NO). Although spatial orientation has been extensively studied in honeybees at the behavioral level, most electrophysiological and anatomical analyses have been carried out in other insect species, leaving the morphology and physiology of neurons that constitute the CX in the honeybee mostly enigmatic. The goal of this study was to morphologically identify neuronal cell types of the CX in the honeybee Apis mellifera. By performing iontophoretic dye injections into the CX, we traced 16 subtypes of neuron that connect a subdivision of the CX with other regions in the bee's central brain, and eight subtypes that mainly interconnect different subdivisions of the CX. They establish extensive connections between the CX and the lateral complex, the superior protocerebrum and the posterior protocerebrum. Characterized neuron classes and subtypes are morphologically similar to those described in other insects, suggesting considerable conservation in the neural network relevant for orientation.},
  language  = {en}
}
@article{HeldBerzHensgenetal.2016,
  author    = {Held, Martina and Berz, Annuska and Hensgen, Ronja and Muenz, Thomas S. and Scholl, Christina and R{\"o}ssler, Wolfgang and Homberg, Uwe and Pfeiffer, Keram},
  title     = {Microglomerular Synaptic Complexes in the Sky-Compass Network of the Honeybee Connect Parallel Pathways from the Anterior Optic Tubercle to the Central Complex},
  series = {Frontiers in Behavioral Neuroscience},
  volume    = {10},
  journal   = {Frontiers in Behavioral Neuroscience},
  number    = {186},
  doi       = {10.3389/fnbeh.2016.00186},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165080},
  year      = {2016},
  abstract  = {While the ability of honeybees to navigate relying on sky-compass information has been investigated in a large number of behavioral studies, the underlying neuronal system has so far received less attention. The sky-compass pathway has recently been described from its input region, the dorsal rim area (DRA) of the compound eye, to the anterior optic tubercle (AOTU). The aim of this study is to reveal the connection from the AOTU to the central complex (CX). For this purpose, we investigated the anatomy of large microglomerular synaptic complexes in the medial and lateral bulbs (MBUs/LBUs) of the lateral complex (LX). The synaptic complexes are formed by tubercle-lateral accessory lobe neuron 1 (TuLAL1) neurons of the AOTU and GABAergic tangential neurons of the central body's (CB) lower division (TL neurons). Both TuLAL1 and TL neurons strongly resemble neurons forming these complexes in other insect species. We further investigated the ultrastructure of these synaptic complexes using transmission electron microscopy. We found that single large presynaptic terminals of TuLAL1 neurons enclose many small profiles (SPs) of TL neurons. The synaptic connections between these neurons are established by two types of synapses: divergent dyads and divergent tetrads. Our data support the assumption that these complexes are a highly conserved feature in the insect brain and play an important role in reliable signal transmission within the sky-compass pathway.},
  language  = {en}
}