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recognition & localization of predators & prey feature analyzers in the brain

PART 2: SENSORY WORLDS #09: FEATURE ANALYSIS IN TOADS I. 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. recognition & localization of predators & prey

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recognition & localization of predators & prey feature analyzers in the brain

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

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

  3. FEATURE ANALYSIS IN TOADS • 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

  4. FEATURE ANALYSIS IN TOADS • 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

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

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

  7. RECOGNITION & LOCALIZATION OF PREDATORS & PREY • 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

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

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

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

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

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

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

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

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

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

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

  18. RECOGNITION & LOCALIZATION OF PREDATORS & PREY • 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)

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

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

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

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

  23. FEATURE ANALYZERS IN THE BRAIN • 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

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

  25. FEATURE ANALYZERS IN THE BRAIN • 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

  26. FEATURE ANALYZERS IN THE BRAIN • 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

  27. FEATURE ANALYZERS IN THE BRAIN • 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)

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

  29. FEATURE ANALYZERS IN THE BRAIN • 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

  30. p.106 fig.4.8 FEATURE ANALYZERS IN THE BRAIN • 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...

  31. FEATURE ANALYZERS IN THE BRAIN • 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  46. FEATURE ANALYZERS IN THE BRAIN • 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

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