Colour Vision: Self-Centered Fly Photoreceptors Communicate over Distances.

A new study shows that the synaptically interconnected axon terminals of colour-sensitive fly photoreceptors that sample the same point in visual space receive additional inhibition from surrounding units; the resulting additional chromatic comparisons result in an optimal decorrelation of photoreceptor inputs. There are striking parallels between newly identified horizontal interactions and those mediated by mammalian horizontal cells.

Cellular and synaptic adaptations of neural circuits processing skylight polarization in the fly.

Specialized ommatidia harboring polarization-sensitive photoreceptors exist in the 'dorsal rim area' (DRA) of virtually all insects. Although downstream elements have been described both anatomically and physiologically throughout the optic lobes and the central brain of different species, little is known about their cellular and synaptic adaptations and how these shape their functional role in polarization vision. We have previously shown that in the DRA of Drosophila melanogaster, two distinct types of modality-specific 'distal medulla' cell types (Dm-DRA1 and Dm-DRA2) are post-synaptic to long visual fiber photoreceptors R7 and R8, respectively.

Insect Responses to Linearly Polarized Reflections: Orphan Behaviors Without Neural Circuits.

The e-vector orientation of linearly polarized light represents an important visual stimulus for many insects. Especially the detection of polarized skylight by many navigating insect species is known to improve their orientation skills. While great progress has been made towards describing both the anatomy and function of neural circuit elements mediating behaviors related to navigation, relatively little is known about how insects perceive non-celestial polarized light stimuli, like reflections off water, leaves, or shiny body surfaces.