NROC34 - Lec 5 - Vision in honeybees (exam summary).doc

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Andrew Mason

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Lec 5: VISION IN HONEYBEES • Vision dimensions: o Light intensity o Wavelength variance/intensity o motion • Invertebrate Vision: o Insects/crustaceans  Most = compound eyes o Cephalopods (squid family)  Similar to vertebrates o Arachnids  Simple eyes = single lens • Jumping spiders: o 8 eyes = 4 pairs  secondary eyes = motion detection  principle eyes = feature detection • front = most well developed • best spatial resolution o single lens + underlying retina o retina moves under lens = scan the object • Mantis shrimp: o Most complex color visual sys known o 16 diff visual pigments o eyes specialized in diff regions that are looking at diff attributes o scan w/ eyes = get info • Insects: o 2 main eyes = compound eyes o several small simple eyes = ocelli o visual sensors w/ much fewer receptors underlying them Simple Eyes Compound Eyes • arachnids • insects • single lens • ommatidia = facets on surface = mosaic of small cells • spatial resolution determined by density of ommatidia; angle between neighboring ommatidia (interommatidial angle) = defines resolution of points in visual space that can be detected separately • sensitivity determined by ommatidia size • trade-off btn sensitivity and resolution • bigger lens = captures more light = more sensitive BUT also looking at larger space  resolution is smaller • Active vision: o Visual process = involves eye mvt o Motion can be used to acquire visual cues o Invertebrate = impt b/c they have limited neural resources HONEYBEES: • Social insects: o 20,000 workers • Collective foraging: o Coordinated activity o Must be able to:  Navigate  Learn  Communicate • Recruitment not by directly leading them, but by communication via dance language • Dance language: o Waggle dance o Figure 8 pattern and going up middle • Hive w/ sugar water in front which foragers come out and find  Foragers go back and provide info to recruits about location  Dish moved 25% further away each time  Recruits come out and don’t find sugar water in the place they were told to look; they’ll look a bit further down  Trains bees to go to remote locations from hive  Check what is it about each dance that indicates location? Decipher the dance: • Angle relative to vertical = direction of food source relative to the sun viewed from hive entrance • # of waggles in centre = distance • the repeated cycles aren’t exactly same each time; recruits take average of all the cycles to get accurate location of food source • foragers find source by indirect route but will communicate DIRECT route in their dance b/c as they fly back, they tally up the displacement vectors from the hive • dance signals = acoustic, vibrational, tactile, chemical Bees compute: • distance from food source & hive • direction to food source from hive Bees learn: • details of food source location • which flowers = good • which artificial feed = correct Learning Tests: • hierarchy of cues: odor, color, pattern • timing: o they acquire the cue that they saw during approach o show preference for odor 1 at 10 AM and preference for odor 2 at 3 PM which is what odors they experienced during those particular times • learning requires the ability to generalize b/c stimuli are variable o diagonal pattern is what they were tra
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