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Problem 2 (deficits in visual perception (akinetopsia (inability to…

- - - - affects contralateral side of space
  - - - lesion to one area of brain
        
        affects one function associated to that region, but not another
    - - 2 mental processes working independently
      - exp. A = one can perform x, but not y. exp. B = one can perform y, but not x
- - - - upper half of calcarine sulcus responds to lower visual field
      - lower half of calcarine sulcus responds to upper visual field
    - - objects in center of vision observed with higher detail
    - - simple cells
        
        excitatory area inside, inhibitory area outside
        
        minimal spontaneous activity
        
        on-off mechanism
        
        orientation specificity
      - complex cells
        
        larger receptive field
        
        lacks an excitatory/inhibitory component
        
        specific orientation, direction of movement is important
      - hypercomplex cells
        
        respond to direction, orientation, length, width, shapes
        
        distributed over 6 layers of V1
      - cells organized in hypercolumns
        
        each row of cells responds to different orientation
        
        location--> same spot on retina
        
        includes all orientations (0-180degress both sides)
        
        occular dominance
  - - - thin = color info, thick = motion info
- - - - ipsilateral temporal hemiretina
        
        temporal semiretina fibers stay on the same side
      - contralateral nasal semiretina
        
        nasal (inside) fibers crossed to opp. side of brain
        
        nasal semiretina crosses over via optic nerve at optic chiasm
  - - - info travels to V1 & V5
        
        returning signals = back projections
    - - rapid responses, sensitive to illumination changes
      - sensitive to motion changes
      - large cell bodies
    - - fibers projecting onto cortex
    - - fixation cells
        
        front portion of intermediate layer
        
        active when fixated on an object
      - burst cells
        
        active during eye movement
        
        activity begins 20ms before eye movement
      - buildup cells
        
        anticipating eye movement
- - - - layers 3-6 consist of parvo cells
        
        small cell bodies with dense branching
        
        receive input from parvo ganglion cells
        
        color sensitive + low-contrast sensitivity
      - layer 1 &2 consist of magno cells
        
        receive input from magno ganglion cells
        
        high-contrast sensitivity, motion detection, depth perception
    - - axons of later geniculate neurons