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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
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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
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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
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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
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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
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vision
> auditory, olfactory, tactile senses
responses triggered by movement
RECOGNITION & LOCALIZATION OF PREDATORS & PREY
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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
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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
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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
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natural environment
not rigid linked o-a-f-s sequence
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
RECOGNITION & LOCALIZATION OF PREDATORS & PREY
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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
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prey-catching in the laboratory
hunger motivation to attempt prey capture
definition...
p.97
fig.
4.1
RECOGNITION & LOCALIZATION OF PREDATORS & PREY
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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
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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
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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
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prey-catching in the laboratory
worm variations releasers ? contrast orientation thickness composition direction
p.101 fig.4.4
RECOGNITION & LOCALIZATION OF PREDATORS & PREY
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p.101 fig.4.4
prey-catching in the laboratory
worm variations releasers ? contrast orientation thickness composition direction
velocity
RECOGNITION & LOCALIZATION OF PREDATORS & PREY
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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
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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
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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
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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
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toad visual system
retina (vertebrates), 5 cell types receptor cells bipolar cells ganglion cells horizontal cells amacrine cells
FEATURE ANALYZERS IN THE BRAIN
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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