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$ recognition & localization of predators & prey $ feature analyzers in the brain $ from recognition to response $ summary PART 2: SENSORY WORLDS #09:

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Presentation on theme: "$ recognition & localization of predators & prey $ feature analyzers in the brain $ from recognition to response $ summary PART 2: SENSORY WORLDS #09:"— Presentation transcript:

1 $ recognition & localization of predators & prey $ feature analyzers in the brain $ from recognition to response $ summary PART 2: SENSORY WORLDS #09: FEATURE ANALYSIS IN TOADS I

2 $ recognition & localization of predators & prey $ feature analyzers in the brain $ from recognition to response $ summary PART 2: SENSORY WORLDS #09: FEATURE ANALYSIS IN TOADS I

3 $ common toad – Bufo bufo $ order: Anura $ family: Bufonidae $ ~ 200 toad species $ environment $ adaptable to climate $ prefer temperate & humid $ reproduction $ patterns ~ rainfall $ species-specific  mate calls FEATURE ANALYSIS IN TOADS

4 $ prey $ insects, beetles, earthworms $ larger toads... birds, frogs $ predators $ snakes, birds, carnivorous mammals $ middle of the food chain $ sensory: predator or prey signal ? $ motor: appropriate behavior $ opposite responses to stimuli $ must be fast FEATURE ANALYSIS IN TOADS

5 $ interesting neuro-ethology subjects because of $ highly selective (not merely sensitive ) visual system $ classify predator & prey signals $  appropriate behavior $ accessible visual system FEATURE ANALYSIS IN TOADS

6 $ vision $ > auditory, olfactory, tactile senses $ responses triggered by movement RECOGNITION & LOCALIZATION OF PREDATORS & PREY

7 $ natural environment $ stereotypic responses to predator & prey $ distinguished using aspects of moving stimulus $ prey vs non-prey  $ 4 types of response $ orient ( o ) $ approach ( a ) $ fixate ( f ) $ snap ( s ) p.97 fig.4.1 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

8 $ natural environment $ FAP ? $ innate responses $ naïve animals do it... $ linked action patterns $ only o-a-f-s sequence ? $ sign stimuli ? $ releasing mechanism ? p.97 fig.4.1 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

9 $ natural environment $ feature detector $ neuron(s) $ selectively responsive $ specific stimulus $ does it work this way ? p.97 fig.4.1 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

10 $ natural environment $ not rigid linked o-a-f-s sequence $ different stimulus  different response sequence $ eg : constant distance  o-o-o-o-o- o... (lab experiment) $ ~ distance & movement $ no behavioral prerequisites $  not true FAP p.99 fig.4.2 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

11 $ natural environment $ possible identified features of small invert. prey $ elongated shape $ movement parallel to body axis $ used in lab experiments to study neural mechanisms RECOGNITION & LOCALIZATION OF PREDATORS & PREY

12 $ prey-catching in the laboratory $ hunger  motivation to attempt prey capture $ definition... p.97 fig.4.1 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

13 $ prey-catching in the laboratory $ glass cylinder $ cardboard dummy stimuli $ 3 “worm” types $ rotated 20°/s $ releasing value $ o / min $ direction p.99 fig.4.2 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

14 $ prey-catching in the laboratory $ optimal dummy stimulus ? $ shape $ size ( s ) $ color $ contrast $ orientation $ thickness $ composition $ velocity p.99 fig.4.2 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

15 $ prey-catching in the laboratory $ worm stimulus  releasing value  ~ s $ antiworm (= “amount”)  releasing value  ~ s $ square  biphasic ~ s (bugs  predators ?) p.100 fig.4.3 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

16 $ prey-catching in the laboratory $ worm variations  releasers ? $ contrast $ orientation $ thickness $ composition $ direction p.101 fig.4.4      RECOGNITION & LOCALIZATION OF PREDATORS & PREY

17 p.101 fig.4.4 $ prey-catching in the laboratory $ worm variations  releasers ? $ contrast $ orientation $ thickness $ composition $ direction      $ velocity RECOGNITION & LOCALIZATION OF PREDATORS & PREY

18 $ prey-catching in the laboratory $ toads respond to shape + direction $ in variety of conditions  invariance $ recognition robust $ informs about releasing mechanism $ relationship critical  configural property $ emergent (whole > sum of parts) RECOGNITION & LOCALIZATION OF PREDATORS & PREY

19 $ prey-catching in the laboratory $ toads respond to shape + direction $ response to $ continuum ~ threshold $ not single feature $ response  ~ velocity $ more is better... p.101 fig.4.4 RECOGNITION & LOCALIZATION OF PREDATORS & PREY

20 $ toad visual system $ retina (vertebrates) $ optic nerve $ contralateral $ optic tectum $ thalamic pretectum (TP) (fewer projections) p.103 fig.4.5 FEATURE ANALYZERS IN THE BRAIN

21 $ toad visual system $ retina (vertebrates), 5 cell types $ receptor cells $ bipolar cells in series $ ganglion cells $ horizontal cells $ amacrine cells FEATURE ANALYZERS IN THE BRAIN

22 $ toad visual system $ retina (vertebrates), 5 cell types $ receptor cells  bipolar cells  ganglion cells $ horizontal cells $ amacrine cells FEATURE ANALYZERS IN THE BRAIN

23 $ toad visual system $ retina (vertebrates), 5 cell types $ receptor cells: input elements, transduce light $ rods $ cones $ bipolar cells: relay elements $ ganglion cells: output  brain via optic nerve $ horizontal cells $ amacrine cells lateral interactions with retina FEATURE ANALYZERS IN THE BRAIN

24 $ toad visual system $  retinal ganglion cell receptive fields $ space that excites or inhibits neuron activity $ circular, 2 concentric regions $ center $ surround FEATURE ANALYZERS IN THE BRAIN

25 $ toad visual system $  retinal ganglion cell receptive fields $ space that excites or inhibits neuron activity $ circular, 2 concentric regions $ center: excitatory (ERF) $ surround: inhibitory (IRF) p.104 fig.4.6 FEATURE ANALYZERS IN THE BRAIN

26 $ toad visual system $  retinal ganglion cell receptive fields $ space that excites or inhibits neuron activity $ circular, 2 concentric regions $ center: inhibitory (IRF) $ surround: excitatory (ERF) p.104 fig.4.6 FEATURE ANALYZERS IN THE BRAIN

27 $ toad visual system $  retinal ganglion cell receptive fields $ space that excites or inhibits neuron activity $ circular, 2 concentric regions $ center $ surround $ retinal ganglion cells distinguished by $ position (lateral axis) $ IRF & ERF strengths (longitudinal axis) FEATURE ANALYZERS IN THE BRAIN

28 $ toad visual system $ ganglion cells $ contralateral $ orderly maps  retinotopic projections $ optic tectum $ thalamic pretectum (TP) p.105 fig.4.7 FEATURE ANALYZERS IN THE BRAIN

29 $ toad visual system $ ganglion cells $ contralateral $ orderly maps  retinotopic projections $ neuron classes R1-6  different layers $ optic tectum $ thalamic pretectum (TP) p.103 fig.4.5 FEATURE ANALYZERS IN THE BRAIN

30 $ retinal ganglion cell responses to relevant stimuli $ neurons that respond (spike) differentially ? $ prey recognition neurons / families of neurons ? $ extracellular recordings $ 6 neuron classes (R1  R6) $ early findings, center ERFs: $ R2: 4° $ R3: 8° $ R4: 16° $ no stimulus quality info... p.106 fig.4.8 FEATURE ANALYZERS IN THE BRAIN

31 $ retinal ganglion cell responses to relevant stimuli $ no classes of neurons respond ~ behavior... $ no  response ~  long axis of stimulus $ no worm preference $ antiworm ~ square p.107 fig.4.9 FEATURE ANALYZERS IN THE BRAIN

32 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field... $ eg, R3 cells p.107 fig.4.9 FEATURE ANALYZERS IN THE BRAIN

33 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8° ERF IRF FEATURE ANALYZERS IN THE BRAIN

34 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

35 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

36 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

37 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

38 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

39 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

40 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

41 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

42 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

43 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

44 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

45 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field p.107 fig.4.9 8°  FEATURE ANALYZERS IN THE BRAIN

46 $ retinal ganglion cell responses to relevant stimuli $ how do receptive fields ~ responses ? $ stimulus movement ~ receptive field... $ logic works for R2 & R4 $ does not find feature analyzers in brain p.107 fig.4.9 FEATURE ANALYZERS IN THE BRAIN


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