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SUMMARY:Neural Processing of Naturalistic Features by the Hoverfly Visual 
 System - Dr Karin Nordström\, Uppsala University\, Sweden
DTSTART:20150219T160000Z
DTEND:20150219T170000Z
UID:TALK56416@talks.cam.ac.uk
CONTACT:16026
DESCRIPTION:Whereas sinusoidal gratings and other relatively simple stimul
 i have been used extensively in visual research\, these are hardly represe
 ntative 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.  \n\nNatural scenes\, 
 which are more commonly encountered by freely flying flies\, can be descri
 bed in terms of their second-order statistics. For instance\, it has been 
 shown that the slope of the average amplitude spectrum (often called the a
 lpha-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 t
 o the human observer as more blurry. \n\nWe have investigated how the seco
 nd-order statistics\, and mainly the alpha value\, affect visual responses
  in hoverflies by using a higher-order visual neuron that we recently desc
 ribed. 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 inhibitio
 n is closely coupled with the image’s alpha value\, so that peak inhibit
 ion is seen at alphas close to 1\, i.e. at values previously shown to be m
 ost prevalent in scenes typically encountered by flies.\n\n\nSpeaker's web
 site:\n\nhttp://www.neuro.uu.se/research/physiology/neurophysiology-of-mot
 ion-vision/?languageId=1\n\n\n\n**Free wine\, snacks and a chance to meet 
 the speaker in the Physiology Tea Room after the talk**
LOCATION:Hodgkin Huxley Seminar Room\, Physiology Building\, Downing Site
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