Active Processes in Perception, in Vision and in Electric Fish. - PowerPoint PPT Presentation

Active Processes in Perception, in Vision and in Electric Fish. Curtis Bell Neurological Sciences Institute Oregon Health and Science University

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.

Perception is unconscious inference. - Helmholtz

Satellite Picture? X-ray Image?

Or Cow’s Face?

Most Connections Are Probably Plastic

Examined Object and Eye Movements Exploring It Yarbus

Contrast and Luminance Vary Between Fixation Points as Does Time Between Saccades. These Differences Will Affect Neural Responses. Mante et al., 2006

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

Intended Eye Movements Remap Visual Space Duhamel et al., 1992

Remapping occurs before saccade and so requires corollary discharge mechanism. Duhamel et al., 1992

Corollary Discharge Signals Keep the World Stable During Smooth Pursuit Eye Movements Thier, Lindner & Haarmeier

Eye Movements Constrain (Disambiguate) Visual Perception Hafez and Krauzlis, 2006

Hafez and Krauzlis, 2006

Non-Conducting Conducting Object Object Lissman, 1963

Nate Sawtell and Alan Williams

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).

Electroreceptors on the Trunk of the Fish 1 mm

Afferent Fiber from Mormyromast Electroreceptor Szabo and Fessard, 1965

Effects of Objects on Afferent Responses Gomez et al., 2003

Sawtell, Williams, von der Emde, & Bell

Dependence of Latency on EOD Interval Constant amplitude stimuli presented at a naturally occurring sequence of intervals. Nate Sawtell and Alan Williams

Contrast and Luminance Vary Between Fixation Points as Does Time Between Saccades. These Differences Will Affect Neural Responses. Mante et al., 2006

Electric Organ Corollary Discharge Effects in Active Electrolocation System

Use of Corollary Discharge to Measure Afferent Latency

Variation in corollary discharge could be used to minimize effects of interval and amplitude changes.

Electric Organ Corollary Discharge Effects in Active Electrolocation System

Schema of Cerebellum-like Structures

Anti-Hebbian Spike Timing Dependent Synaptic Plasticity

Electric Organ Corollary Discharge Plasticity

Response to central corollary discharge signal is essentially the same as response to sensory stimulus.

Corollary Discharge Signals Keep the World Stable During Smooth Pursuit Eye Movements Thier, Lindner & Haarmeier

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.