Keram Pfeiffer

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The central complex is a group of modular neuropils across the midline of the insect brain. Hallmarks of its anatomical organization are discrete layers, an organization into arrays of 16 slices along the right-left axis, and precise inter-hemispheric connections via chiasmata. The central complex is connected most prominently with the adjacent lateral(More)
Many animals use the sun as a reference for spatial orientation [1-3]. In addition to sun position, the sky provides two other sources of directional information, a color gradient [4] and a polarization pattern [5]. Work on insects has predominantly focused on celestial polarization as an orientation cue [6, 7]. Relying on sky polarization alone, however,(More)
Many migrating animals employ a celestial compass mechanism for spatial navigation. Behavioral experiments in bees and ants have shown that sun compass navigation may rely on the spectral gradient in the sky as well as on the pattern of sky polarization. While polarized-light sensitive interneurons (POL neurons) have been identified in the brain of several(More)
Many migrating animals use a sun compass for long-range navigation. One of the guiding cues used by insects is the polarization pattern of the blue sky. In the desert locust Schistocerca gregaria, neurons of the central complex, a neuropil in the center of the brain, are sensitive to polarized light and might serve a key role in compass navigation. Visual(More)
The anterior optic tubercle is a small neuropil in the insect brain and a major target of visual interneurons from the optic lobe. The functional role of the tubercle is poorly understood, but recent evidence from locusts points to a possible involvement in polarization vision. The present study examines the organization of the anterior optic tubercle in(More)
Visually guided behaviors require the brain to extract features of the visual world and to integrate them in a context-specific manner. Hymenopteran insects have been prime models for ethological research into visual behaviors for decades but knowledge about the underlying central processing is very limited. This is particularly the case for sky-compass(More)
GABA and glutamate receptors belonging to the ligand-gated chloride-channel family are primary targets of insecticides and antiparasitics, so their molecular structure, pharmacology and biophysical properties have attracted significant attention. However, little is known about the physiological roles of these channels or how they regulate neuronal(More)
Many animals rely on a sun compass for spatial orientation and long-range navigation. In addition to the Sun, insects also exploit the polarization pattern and chromatic gradient of the sky for estimating navigational directions. Analysis of polarization-vision pathways in locusts and crickets has shed first light on brain areas involved in sky compass(More)
Animals relying on a celestial compass for spatial orientation may use the position of the sun, the chromatic or intensity gradient of the sky, the polarization pattern of the sky, or a combination of these cues as compass signals. Behavioral experiments in bees and ants, indeed, showed that direct sunlight and sky polarization play a role in sky compass(More)
Neurons receive, process and transmit information using two distinct types of signaling methods: analog signals, such as graded changes in membrane potential, and binary digital action potentials. Quantitative estimates of information in neural signals have been based either on information capacity, which measures the theoretical maximum information flow(More)