lecture 16

Question 1

visual field

Answer 1

total area in which objects can be seen in peripheral vision when eyes r fixed on a point
- left and right visual fields (info goes to opposite hemisphere)

Question 2

coding location

Answer 2

light falling on one place on the retina will activate one ganglion cell and light falling on another will activate a different cell
- each RGC responds to stimulation on just 1 patch of retina

Question 3

receptive field hierarchy

Answer 3

ganglion cell < LGN cell < V1

Question 4

where is acuity best

Answer 4

central part of visual field- fovea sends information to a disproportionately large part of occipital cortex

Question 5

where is acuity best

Answer 5

central part of visual field- fovea sends information to a disproportionately large part of occipital cortex

Question 6

retinal ganglion cells

Answer 6

respond to prescence or abscence of light but not shape

- receptive fields are circular

Question 7

on/off center cells

Answer 7

on- excited when light falls on center of receptive field and inhibited in surround (weak excitation)
off- excited when light falls on sorround and inhibited when light falls of center (weak inhibition)

Question 8

how does brain go from on-off receptivity to shape

Answer 8

RGCs tell brain amount of light. hitting a certain spot relative to the average in the surrounding area

Question 9

luminance contrast

Answer 9

amount of light reflected by an object relative to its surroundings

Question 10

V1 cell processing

Answer 10

respond to more complex stimuli than light because they receive input from multiple RGC
- orientation detectors: excited by orientation in particular directions

Question 11

simple cells- V1

Answer 11

receptive field with rectangular on/off layout

- respond best to stimulation in specific orientation

Question 12

complex cells- V1

Answer 12

maximally excited by bars of light moving in particular direction through receptive field
0 direction of movement

Question 13

hypercomplex cells (end-stopped)- V1

Answer 13

maximally respond to moving bars (like complex)

also have strong inhibitory area at one side of receptive field

Question 14

how do we go from circular receptive fields to rectangular ones

Answer 14

bars of light strike the receptive field of many RGC input comes from a gorup of ganglion cells aligned in a row, V1 is activated when a bar of light hits retina in particular row of ganglion cels

Question 15

ocular dominance columns

Answer 15

neurons are organized into functional columns

• neurons with similar functions
• inputs arrive in layer 4 then connect vertically
• input from left or right eye

Question 16

trichromatic theory

Answer 16

receptor level0 explanation of color vision based on the coding of three primary colors (red, green and blue)
color is determined by relative responses of diff cone types

Question 17

what can trichromatic theory not explain

Answer 17

what about yellow

cannot explain afterimages: red-green and blue-yellow

Question 18

opponent proces theory

Answer 18

neural level-
explanation of color vision that emphasizes importance of opposite colors (R-G, B-Y)
occurs in retinal ganglion cells

Question 19

injury to ventral stream

Answer 19

what pathway- agnosia
visual form: inability to recognize objects or drawings
face agnosia: ianbility to recognize faces
- cannot recognize objects but can copy objects and shape hands to grasp

Question 20

injury to the how pathway

Answer 20

optic ataxia- deficit in the visual control of reaching and other movements
parietal cortex
- retention of ability to recognize objects normally