Saccadic Suppression has an Extraretinal origin'

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Yarbus 1967
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Le saccadi

• Servono per spostare lo sguardo, posizionando gli
  oggetti di interesse sulla fovea.
• Sono movimenti rapidi e balistici.
• Possono essere involontarie o volontarie.
• La velocità è fra 200 e 900 gradi/sec

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Two problems produced by saccades

• Fast large-field retinal motion.
• Continuous displacement of retinal image.

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Contrast sensitivity at saccadic velocities
Saccadic velocities 200 - 900 deg/sc
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Efference copyCorolary discharge
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SCREEN
MIRROR
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Single cell of monkey MT
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Human blank background
Human texture background
Monkey
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Monkey MT
Michael Kubischik, Bart Krekelberg Frank
Bremmer Dept.Zoology Neurobiology, Ruhr-Univ.
Bochum
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In MT la selettività per la direzione cambia
durante i movimenti saccadici
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Evidenza da imaging
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A che livello riaggisce la soppressione
saccadica?
Burr, D. Eye Movements Keeping Vision Stable
Current Biology 2004
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Stimolazione elletrica della retina e della
cortex
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I blinks(gli ammiccamenti)
Burr Vision in the blink of an eye. Current
Biology, 2005
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Soppressione durante il blinking
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Le aree sopresse durante il blinking
Rosso aree visive sopresse durante il
blinking Verde aree occulomotori sopresse
durante il blinking
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Two problems produced by saccades

• Fast large-field retinal motion.
• Continuous displacement of retinal image.

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We make 3 saccades per second Continual
displacement of retinal information

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Auditory localisation of visual target in
darkLeonard Matin Science 1981
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Von Holst und Mittelstaedt 1954 Sperry 1950
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Real saccades
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Simulated saccades
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Physiological correlates to compression?
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Remapping can precede the saccade.
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Remapping can precede the saccade
Time (ms)
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LIP population response Kubischik, Krekelberg
Bremmer
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Remapping in humans psychophysics
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Remapping in humans psychophysics
Melcher Nature Neurosc. 2007
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Remapping in humans psychophysics
left
right
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Remapping in humans and monkeys
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Two Visual Streams of Processing Goodale and
Milner
Posterior Parietal Cortex
Pulv
Dorsal Action Stream
SC
Retina
V1
LGNd
Ventral Perception Stream
Inferotemporal Cortex
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Dorsal
Ventral
Goodale, M.A. Humphrey, G.K. (1998).
Cognition.
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Patient DF
Control
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Illusions fool the eye but not the hand in
normals Aglioti, De Souza Goodale
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Lillusione inganna locchio ma non la mano
(Agliotti et Goodale, 1995)
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Verbal report shutter closed
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Pointing shutter closed
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Pointing shutter closed Verbal report shutter
closed
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Pointing shutter closed Verbal report shutter
closed
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Pointing eyes closed
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Pointing eyes closedVerbal shutter closed
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Illusion returns when vision availablePointing
eyes and shutter open
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Illusion returns when vision availablePointing
eyes and shutter openVerbal shutter closed
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The results support the idea of separate
representations of visual space for perception
and action.

• The perceptual system is plastic and subject to
  distortion during saccades.
• The action system remains veridical during
  saccades (to guide eye movments).
• When both systems are available the perceptual
  system dominates.