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Neural Processing of Naturalistic Features by the Hoverfly Visual System

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Whereas sinusoidal gratings and other relatively simple stimuli have been used extensively in visual research, these are hardly representative of what an animal would encounter in its normal ecosystem. I will here describe work we have done investigating how neurons in the hoverfly visual system respond to more naturalistic stimuli.

Natural scenes, which are more commonly encountered by freely flying flies, can be described in terms of their second-order statistics. For instance, it has been shown that the slope of the average amplitude spectrum (often called the alpha-value) of natural scenes show a Gaussian distribution aorund 0.6 – 1.7, with a peak close to 1.2. An image with a higher alpha value appears to the human observer as more blurry.

We have investigated how the second-order statistics, and mainly the alpha value, affect visual responses in hoverflies by using a higher-order visual neuron that we recently described. The cSIFE neuron is inhibited by stationary sinusoidal gratings and excited by high-frequency flicker. We show that a range of natural scenes also inhibit cSIFE. By manipulating the images we show that the inhibition is closely coupled with the image’s alpha value, so that peak inhibition is seen at alphas close to 1, i.e. at values previously shown to be most prevalent in scenes typically encountered by flies.

Speaker’s website:

http://www.neuro.uu.se/research/physiology/neurophysiology-of-motion-vision/?languageId=1

Free wine, snacks and a chance to meet the speaker in the Physiology Tea Room after the talk

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