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NROC34: Lec 5: Vision in Honeybees

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Andrew Mason

NROC34 Lec 5 Vision HONEYBEESSlide 1 A reminder of the big pictureOverall idea is that were trying to understand adaptive behavior in terms of discrete mechanisms identifiable and explainable elementsThis combines behavioural and neural analyses and you can think of the behavior as defining the phenomenology and then were looking at the mechanistic side of the behaviorNervous system is best understood in terms of its evolved fxn and that fxn is the natural adaptive behSlide 3 Vision is ComplexVisionmore complicated than hearing in certain ways bc visual stimuli vary along several dimensionsVisual stimuli oSpatial patterns of light intensityoVary in wavelengthintensitycolor differencesoIf change over timemotionSlide 4 Spatial PatternDisplays spatial intensity distributionIf you see this visual scene as a map of intensity values at each location in the image pixel valuesThis would be one pattern of spatial intensity variation and this would be another one is simpler than the other etcSlide 5 ColorCan have the same spatial pattern of intensity variation but another type of variation could be intensity at diff wavelength colorThese are all the same spatial patterns but in diff colorsSlide 6 MotionSame spatial intensity pattern slide across screenthe speed and direction of movement will cause the pattern to vary in the way it stimulates the retina over timeSlide 7 Invertebrate VisionInsects and crustaceans have compound eyes but not true of all invertebrates There are invertebrates such as cephalopods squid family which have imageforming eyes which are remarkably similar to vertebrate eye structureArachnidssimple eyes bc have single lens as opposed to having compound eyesSlide 8 Cephalod eyeSimilar to vertebrate eyeSlide 9 Simple eye spiderMost spiders dont have very good vision at all while jumping spiders have the best and this is bc rather than sitting on web waiting for prey to come along jumping spiders are hunters and therefore have better visionJumping spiders are wandering spiders that travel thru the enviro locating prey and navigating by visionJumping spiders4 pairs of eyesoPrimary eyes at frontmost well developedbest spatial resolutionoSingle lensunderlying retinaoTo direct their gaze via eye mvts and its via mvt of the retinacan shift retina around in diff directions oCan see retina moving under lens they scan in a particular patternoHave high spatial resolution over very limited area and they scan across the object that theyre looking atkind of active visionSlide 10 compound EyeMantis shrimphave most complex color visual system knownoHave around 16 diff visual pigmentsoEyes are specialized in diff regions that are looking at diff attributes some areas are sensitive to polarization they also scan with eyes to get infoInsects have two main eyes compound eyes and they have several small simple eyes ocellioVisual sensors with much fewer receptors underlying themSlide 11 Compound eye crosssectionFacets that make up the surface of the compound eye are a mosaic of small lenses these facets are known as ommatidiaUnder each ommatidiaset of receptors that are aligned with that little lensSpatial resolution of a compound eye is determined by the density of the ommatidia angle btn neighboring ommatidia defines the resolution of points in visual space that can be detected separately by such an eyeThe overall sensitivity of the eye is determined by the size of ommatidiaoHave larger lenscaptures more lightmore sensitive therefore requires less light stimulation to be activatedTheres a strict tradeoff btn sensitivity and resolution if you make lens biggermore sensitive bc capture more light but at the same time theyre looking at larger space so resolution is smallerInterommatidial angle btn axis of these lensesdefines how finely subdivided the image can beSlide 12 Active visionVisual processes that involve mvt of the eyesMotion can be used to acquire visual cuesImportant in many invertebrates bc they have limited neural resources to store info about complex visual images and they summarize info of the visual worldSlide 13 Honeybees
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