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Active Processes in Perception, in Vision and in Electric Fish.
Curtis Bell Neurological Sciences Institute Oregon Health and Science University
SLIDE 2 Three ways in which Perception is an Active Process
- The organism exerts behavioral control over a
sensory surfaces (eye movements, ear movements, hand movements, sniffing etc.).
- The organism provides the energy that
activates sensory receptors (echolocation, electrolocation, active touch).
- The organism creates the world it
- experiences. Perception as an active response
to environmental stimuli.
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SLIDE 5 Perception is unconscious inference.
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Satellite Picture? X-ray Image?
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Or Cow’s Face?
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Most Connections Are Probably Plastic
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Examined Object and Eye Movements Exploring It
Yarbus
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Contrast and Luminance Vary Between Fixation Points as Does Time Between Saccades. These Differences Will Affect Neural Responses.
Mante et al., 2006
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Integration of the scene requires information about eye position at different fixation points. This information may be provided by eye movement corollary discharge signals.
Mante et al., 2006
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Intended Eye Movements Remap Visual Space
Duhamel et al., 1992
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Duhamel et al., 1992
Remapping occurs before saccade and so requires corollary discharge mechanism.
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Corollary Discharge Signals Keep the World Stable During Smooth Pursuit Eye Movements
Thier, Lindner & Haarmeier
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Eye Movements Constrain (Disambiguate) Visual Perception
Hafez and Krauzlis, 2006
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Hafez and Krauzlis, 2006
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Conducting Object Non-Conducting Object
Lissman, 1963
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Nate Sawtell and Alan Williams
SLIDE 25 Forms of Active Sensation in Mormyrid Fish
- Generation of the energy that activates
receptors (EODs).
- Variation in the frequency of EODs.
- Variation in the position of the energy
source (electric organ).
- Variation in the position and orientation of
the sensory surface (fish’s body).
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Electroreceptors on the Trunk of the Fish
1 mm
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Afferent Fiber from Mormyromast Electroreceptor
Szabo and Fessard, 1965
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Effects of Objects on Afferent Responses
Gomez et al., 2003
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Sawtell, Williams, von der Emde, & Bell
SLIDE 30 Nate Sawtell and Alan Williams
Constant amplitude stimuli presented at a naturally
- ccurring sequence of intervals.
Dependence of Latency on EOD Interval
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Contrast and Luminance Vary Between Fixation Points as Does Time Between Saccades. These Differences Will Affect Neural Responses.
Mante et al., 2006
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Electric Organ Corollary Discharge Effects in Active Electrolocation System
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Use of Corollary Discharge to Measure Afferent Latency
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Variation in corollary discharge could be used to minimize effects of interval and amplitude changes.
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Electric Organ Corollary Discharge Effects in Active Electrolocation System
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Schema of Cerebellum-like Structures
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Anti-Hebbian Spike Timing Dependent Synaptic Plasticity
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Electric Organ Corollary Discharge Plasticity
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Response to central corollary discharge signal is essentially the same as response to sensory stimulus.
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Corollary Discharge Signals Keep the World Stable During Smooth Pursuit Eye Movements
Thier, Lindner & Haarmeier
SLIDE 44 Collaborators
- Angel Caputi (Uruguay)
- In vivo studies.
- Kirsty Grant (France)
- In vivo and in vitro studies.
- Victor Han (NSI)
- In vitro studies.
- Hans Meek (Netherlands)
- Morphology
- Patrick Roberts (NSI)
- Mathematical modeling.
- Nathaniel Sawtell (NSI)
- In vivo studies
- Alan Williams (NSI)
- In vivo studies and mathematics
- Gerhard von der Emde (Germany)
- In vivo and behavioral studies.
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