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| Imaging unexplored visual circuits in the bee brain
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Since the Nobel Prize Karl von Frisch discovered in the last century that the honey bee Apis mellifera can see colors from the ultraviolet to the orange part of the spectrum, this insect has become a well studied organisms in terms of visually-driven behaviors. Despite their relatively simple brain, bees perceive and learn colors, shapes, patterns, depth, motion, landmark constellations and celestial cues such as position of the sun and polarized light in the sky. Although this rich visual repertoire has been extensively studied at the behavioral level, few neurobiological studies have been performed to uncover the neural mechanisms underlying visual processing. As a consequence some visual areas of the bee brain remain, so far, unexplored. This is the case of a conspicuous structure called the anterior optic tubercle which receives visual input from the compound eyes of the bee.
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In a joint work done by researchers of the Research Center on Animal Cognition of Toulouse, the Arizona State University and the Laboratory of Evolution, Genome and Speciation of Gif-sur-Yvette, an integrative study of the anterior optic tubercle was achieved, by combining neuroanatomical brain reconstructions and a novel procedure for imaging calcium activity in that region of the bee brain upon visual stimulation of the eyes. The work by Theo Mota, a student of the University of Toulouse, which has been just published in The Journal of Neuroscience (1), showed that visual information originating from the dorsal and ventral parts of the bee eye is segregated within distinct compartments of the anterior optic tubercle, both at the input and the output level, in a reversed form of retinotopy.
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Theo Mota |
This study represents the first physiological analysis of visual processing in the bee brain at the neural population level and explains the capacity of bees to behave differently when it comes to respond to visual stimuli presented either to the dorsal or the ventral halves of their compound eyes. |
Fig.: The image shows a honeybee worker brain with fluorescent staining of visual pathways involving the two anterior optic tubercles (one on each side of the brain). Projections of neurons processing information originating from the dorsal (in red) and ventral (in green) parts of bee eyes reveal a clear reversed segregation of dorso-ventral visual input to the optic tubercle. The optic tubercles of both brain hemispheres are connected by two parallel neuronal pathways (in blue) which retain dorso-ventral segregation at the output level. |
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Mota T, Yamagata N, Giurfa M*, Gronenberg W*, Sandoz JC* (2011) 
