Saccadic Suppression has an Extr

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Saccadic Suppression has an Extr Powered By Docstoc
					Yarbus 1967
              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
Two problems produced
     by saccades:

• Fast large-field retinal
  motion.
• Continuous displacement
  of retinal image.
Contrast sensitivity at saccadic velocities

                             Saccadic velocities:
                             200 - 900 deg/sc
 Efference copy
Corolary discharge
                       1000          DB                         norm                MCM        1000
                                                                sac
Contrast Sensitivity




                       100                                                                     100




                        10                                                                     10




                         1                                                                     1
                              0.01        0.1   1          10 0.01      0.1     1         10

                                                    Spatial Frequency (c/deg)
                       1000          DB                     lum   col               MCM        1000
                                                     norm
                                                      sac
Contrast Sensitivity




                       100                                                                     100




                        10                                                                     10




                         1                                                                     1
                              0.01        0.1   1           10 0.01     0.1     1         10

                                                    Spatial Frequency (c/deg)
                            MCM                                JF
Contrast Sensitivity




                       10                                           10




                       1                                            1
                            0     200   400   0        200   400
                                          Delay (ms)
                               Uchikawa & Sato
                       100
Relative Sensitivity


                                                     Saccade
                                                     Normal
                                                     P-Cells
                                                     M-Cells



                       10




                        1
                             500              600     700

                                   Wavelength (nm)
SCREEN




  MIRROR
Single cell of monkey MT
                                                    30     A

                                                    10


Human: blank background




                            Contrast sensitivity
                                                     1


                                                          -300   -200   -100     0    100   200   300

                                                    30     B

                                                    10

Human: texture background
                                                     1


                                                          -300   -200   -100     0    100   200   300


                                                           C
                                Normalised Firing


                                                    10



                Monkey
                                                     1




                                                    0.1
                                                          -300   -200   -100     0    100   200   300
                                                                               Time (ms)
    Dynamics of saccadic suppression
      Psychophysics & Physiology


                   Dynamics of saccadic suppression
                     Psychophysics & Physiology




                                            Diamond et al., 2000
                                                           Diamond et al., 2000
Monkey MT
  Michael Kubischik, Bart Krekelberg Frank Bremmer
        Dept.Zoology & Neurobiology, Ruhr-Univ. Bochum
In MT la selettività per
la direzione cambia
durante i movimenti
saccadici
Evidenza da imaging
       A che livello riaggisce la
       soppressione saccadica?

Burr, D. “Eye Movements: Keeping Vision Stable”
Current Biology 2004
                      100   Simultaneous Masking
Contrast Sensitiity




                       10



                        1
                               1        10         100
                                Mask Contrast
                                                 normal
                                                 saccade
                       100                                       100
Contrast sensitivity




                       10                                        10



                        1                                        1
                                      1          10        100
                             Mask Contrast (%)
Stimolazione elletrica della retina
         e della cortex
         I blinks
   (gli ammiccamenti)


Burr “Vision: in the blink of an
eye”. Current Biology, 2005
                                       LGN     Stimulation alone
                                               Stimulation and blinks
                                 0.4           Blinks in the dark
                                               Predicted visual response
Soppressione                     0.2


durante il                       0.0




               BOLD Signal (%)
blinking                          4
                                       V1      3    V2

                                               2

                                  2
                                               1


                                  0            0

                                  2
                                       V3           MT
                                             0.1

                                  1
                                             0.0


                                  0          -0.1
 Le aree sopresse durante il blinking




Rosso: aree visive sopresse durante il blinking
Verde: aree occulomotori sopresse durante il blinking
Two problems produced
     by saccades:

• Fast large-field retinal
  motion.
• Continuous displacement
  of retinal image.
We make 3
saccades per
second:

Continual
displacement of
retinal
information
Auditory localisation of visual target in dark
       Leonard Matin Science 1981
Horizontal error in auditory localization (deg)

                                                  30                                                                      30
                                                          LM                                                    JS
                                                                                         Control
                                                                                         Paralised
                                                  20                                                                      20



                                                  10                                                                      10



                                                   0                                                                      0



                                                  -10                                                                     -10



                                                  -20                                                                     -20



                                                  -30                                                                     -30
                                                        -30    -20   -10     0      10   -10   0      10   20        30
                                                                           Horizontal eccentricity (deg)
Von Holst und Mittelstaedt 1954
         Sperry 1950
                  30

                  20
                                                                          F1




Position (degs)
                  10

                  0

            -10
                                                                          F0
            -20

            -30
                        -200          -100          0          100
                                             Time (ms)




                                      F0            F1


                  -30          -20   -10       0     10   20         30
                           40                                                              40
                                  MCM                                                JR
Apparent position (degs)


                           20                                                              20

                                                            Target
                            0                                                              0

                                                         Fix
                           -20                                                             -20



                           -40                                                             -40
                                 -200   -100   0   100   200 -200   -100   0   100   200
                                               Delay from saccadic onset
                           40                                                              40
                                  MCM                                                JR
Apparent position (degs)


                           20                                                              20

                                                            Target
                            0                                                              0

                                                         Fix
                           -20                                                             -20



                           -40                                                             -40
                                 -200   -100   0   100   200 -200   -100   0   100   200
                                               Delay from saccadic onset
                           40                                                              40
                                  MCM                                                JR
Apparent position (degs)


                           20                                                              20

                                                            Target
                            0                                                              0

                                                         Fix
                           -20                                                             -20



                           -40                                                             -40
                                 -200   -100   0   100   200 -200   -100   0   100   200
                                               Delay from saccadic onset
Apparent position (deg)

                                MCM                           peri-saccadic   JR
                          40                                                        40
                                                              no-saccade
                          20                                                        20
                                                      Targ

                           0                                                        0
                                                      Fix

                          -20                                                       -20

                          -40                                                       -40
                                -40   -20   0   20   40 -40    -20   0   20    40

                                                 Real position (deg)
                  30

                  20




Position (degs)
                  10
                                                                             F1
                  0

            -10                                                              F0
            -20

            -30
                        -200          -100          0             100
                                             Time (ms)




                                     F0                 F1

                  -30          -20   -10       0     10      20         30
                                             Isoluminant green
                                                                      MRD
Number of bars seen




                      5   HDS                Black bars                     5

                      4                                                     4

                      3                                                     3

                      2                                                     2

                      1                                                     1

                      0                                                     0
                          -100    0    100               -100    0   100

                                 Time from saccade onset (ms)
                    Real saccades
            MCM                                       JR
            4
                                4 bars                      4
            2                                               2
            0                                               0
            4                   3 bars                      4
            2                                               2
Bars seen




            0                                               0
            4                                               4
                                2 bars
            2                                               2
            0                                               0
            4                                               4
            2                  0 or 1 bar                   2
            0                                               0
            -200 -100   0         -200 -100
                            100 200           0   100 200
                               Delay (ms)
SCREEN




  MIRROR
                 MCM
                       Simulated saccades                             JR
            4                                                              4
                                         4 bars
            2                                                              2

            0                                                              0
            4                                                              4
                                         3 bars
            2                                                              2
Bars seen




            0                                                              0
            4                                                              4
                                         2 bars
            2                                                              2

            0                                                              0
            4                                                              4

            2                           0 or 1 bar                         2

            0                                                              0

                -200   -100   0   100       -200     -100   0   100
                                  Delay (ms)
Physiological correlates
   to compression?
 Remapping can precede the
         saccade.
  Stimulus in Stimulus outside Saccade brings     Saccade
receptive field receptive field stimulus into     alone: no
                                receptive field   stimulus
Remapping can precede the saccade

                          0.6
    Normalized Activity

                          0.5
                          0.4
                          0.3
                                                          future
                          0.2                             current
                          0.1
                          0.0
                                -400   -200    0    200   400   600
    t magniture




                          1.0
                                              Time (ms)
                          0.8
                          0.6
LIP population response
 Kubischik, Krekelberg & Bremmer
     Remapping in humans:
        psychophysics

Adapter   Test     Adapter
             Remapping in humans:
                psychophysics




Melcher
Nature Neurosc.
2007
                                      Remapping in humans:
                                         psychophysics

       After-effect magniture   1.0
                                0.8
left
                                0.6
                                0.4
                                0.2
                                0.0

                                      -400   -200   0   200   400   600
  right                                         Time (ms)
Remapping in humans and
monkeys                                  0.6




                Normalized Activity
                                         0.5
                                         0.4
                                         0.3
                                                                       future
                                         0.2                           current
                                         0.1
                                         0.0
                                               -400   -200   0   200   400   600


                After-effect magniture
                                         1.0
                                         0.8
                                         0.6
                                         0.4
                                         0.2
                                         0.0

                                               -400   -200   0   200   400   600
                                                         Time (ms)
Two Visual Streams of Processing
       Goodale and Milner
                         Posterior
                 Pulv
                        Parietal Cortex


          SC


 Retina
          LGNd    V1




                        Inferotemporal
                           Cortex
         Ventral                   Dorsal
      Scene-parsing and          Visual control of
      object identification        motor output
      Scene-based frame         Effector-based frames
        of reference                of reference
      Relational metrics          Absolute metrics
         Propositional               Isomorphic
          Long-term             Moment-to-moment
        representations           computations
         “Conscious”                “Automatic”
Goodale, M.A. & Humphrey, G.K. (1998). Cognition.
             Matching   Posting




Patient DF


   Control
Illusions fool the eye but not the hand in
normals: Aglioti, De Souza & Goodale
L’illusione inganna l’occhio ma non
la mano (Agliotti et Goodale, 1995)
 -20     -16    -12   -8     -4      0    4   8     12   16     20




Fixation




Target
Bar


Eye


LC Shutter

         -200         -100            0       100         200

                                  Time (ms)
                                Verbal report: shutter closed

                                 JR                                              MCM
Apparent Position (deg)




                          20                                                            20


                          10                                                            10


                           0                                                            0


                          -10                                                           -10


                          -20                                                           -20

                                 -20   -10   0   10   20    -20   -10   0   10     20

                                                  Real Position (deg)
                                  Pointing: shutter closed


                                JR                          MCM
Apparent Position (deg)




                          20                                                         20


                          10                                                         10


                           0                                                         0


                          -10                                                        -10


                          -20                                                        -20

                                -20   -10   0   10   20    -20   -10   0   10   20

                                                 Real Position (deg)
                                 Pointing: shutter closed
                                Verbal report: shutter closed
                                 JR                          MCM
Apparent Position (deg)




                          20                                                          20


                          10                                                          10


                           0                                                          0


                          -10                                                         -10


                          -20                                                         -20

                                 -20   -10   0   10   20    -20   -10   0   10   20

                                                  Real Position (deg)
               Pointing: shutter closed
              Verbal report: shutter closed

                          25                                                                      25
                                   JR                                 MCM
Apparent Position (deg)




                          20                                                0.92                  20
                                            0.75
                          15                                                                      15

                                                        0.08                             0.10
                          10                                                                      10


                          5                                                                       5


                          0                                                                       0
                               0        5   10     15   20     25 0    5    10     15   20   25


                                                         Real Position (deg)
                                      Pointing: eyes closed

                                JR                          MCM
Apparent Position (deg)




                          20                                                         20


                          10                                                         10


                           0                                                         0


                          -10                                                        -10


                          -20                                                        -20

                                -20   -10   0   10   20    -20   -10   0   10   20

                                                 Real Position (deg)
                                      Pointing: eyes closed
                                      Verbal: shutter closed
                                JR                          MCM
Apparent Position (deg)




                          20                                                         20


                          10                                                         10


                           0                                                         0


                          -10                                                        -10


                          -20                                                        -20

                                -20   -10   0   10   20    -20   -10   0   10   20

                                                 Real Position (deg)
Illusion returns when vision available
                                Pointing: eyes and shutter open


                                JR                          MCM
Apparent Position (deg)




                          20                                                         20


                          10                                                         10


                           0                                                         0


                          -10                                                        -10


                          -20                                                        -20

                                -20   -10   0   10   20    -20   -10   0   10   20

                                                 Real Position (deg)
Illusion returns when vision available
                                Pointing: eyes and shutter open
                                    Verbal: shutter closed

                                JR                          MCM
Apparent Position (deg)




                          20                                                         20


                          10                                                         10


                           0                                                         0


                          -10                                                        -10


                          -20                                                        -20

                                -20   -10   0   10   20    -20   -10   0   10   20

                                                 Real Position (deg)
    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.

				
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