Power Point 12

Question 1

Level 1. Extraction of basic attributes – _____

Answer 1

retina

Question 2

Level 2. Detection of organizational rules – ________

Answer 2

LGN and primary visual cortex

Question 3

Detection of Color and Contrast – Foreground vs. Background -

Answer 3

Level 2. Detection of organizational rules – LGN and primary visual cortex

Question 4

Object recognition depends on separation of __________

Answer 4

foreground and background

Question 5

To link the elements of visual scene into a unified perception, the visual system circuits relay on organizational rules for grouping:

Answer 5

• segmentation based on similarity, proximity
• contour detection based on good continuation, contour saliency
• segregation of foreground and background based on color, contrast

Question 6

Level 3. Visual information converges – __________

Answer 6

association areas of the visual cortex

Question 7

___________plays a role in what is seen

Answer 7

Expectation

Question 8

Anatomy of Visual Processing:

Answer 8

Low Level - retina

Intermediate Level - lateral geniculate nucleus in the thalamus,primary visual cortex

High Level - association cortical regions:
ventral pathway = to temporal lobe = what: object identification
dorsal pathway = to parietal lobe = where: guiding movement

Question 9

_________ = to temporal lobe = what: object identification

Answer 9

ventral pathway

Question 10

__________ = to parietal lobe = where: guiding movement

Answer 10

dorsal pathway

Question 11

All visual information comes from the ______

Answer 11

retina

Question 12

the _____ forms a variable diaphragm, allowing light rays to enter the eye

Answer 12

pupil

Question 13

the _________ provides refractive optics, projecting small image of the outside world onto the retina lining the back of the eye-ball

Answer 13

cornea

Question 14

The ________ refracts light further, and by changing shape, focuses images of objects located at different distances from the eye.

Answer 14

lens

Question 15

Retina Performs what Three Major Functions?

Answer 15

Phototransduction – photoreceptor cells adsorb light and convert light energy into electric signals
Adaptation – photoreceptors can process visual signal at varying light intensities
Preprocessing – neural circuits in the retina preprocess visual information, extracting primary visual features from information presented.

Question 16

_________ cells modulate information processing

Answer 16

amacrine and horizontal

Question 17

Information transduction:

Answer 17

photoreceptor (input) – bipolar cell – retinal ganglion cell (output)

Question 18

_______ corresponds to the center of visual field, performs highest resolution processing – smallest receptive fields, densest receptor packing. The farther from the fovea – the bigger receptive fields are

Answer 18

Fovea

Question 19

________ is the site where axons of retinal ganglion cells exit the retina forming the optic nerve; it does not contain any photoreceptors, generating blind spot in our vision

Answer 19

Optic Disk

Question 20

Anatomy of Visual Processing

Answer 20

• visual hemifieldregion seen with one eye
• binocular zoneregion seen with both eyes
• monocular crescentperipheral region seen with only one eye
• nasal hemiretina
• temporal hemiretina

Question 21

outer segment – __________ – distal (closest to the back of the eye), contains stacks of membranous disks that contain light-absorbing pigments

Answer 21

phototransduction

Question 22

In response to the pattern of light falling on the retina, photoreceptors in the ______ regions get hyperpolarized, whereas those in the dark regions get _______.

Answer 22

light, depolarized

Question 23

photoreceptors do not fire action potentials, in the dark they continuously release __________

Answer 23

glutamate

Question 24

Two major types of bipolar cells: ___ and ___ respond to the glutamate released at the photoreceptor-bipolar synapse through distinct mechanisms:

Answer 24

ON and OFF

Question 25

OFF bipolar neurons use ionotropic AMPA channels –glutamate depolarizes, fire in ________)

Answer 25

darkness

Question 26

OFF bipolar neurons use metabotropic G-protein coupled receptors. Activation of these receptors hyperpolarizes the cell – silenced in darkness, fire in _______.

Answer 26

light

Question 27

Retina performs 3 major functions:

Answer 27

Phototransduction, Adaptation, Preprocessing

Question 28

Anatomical features of the retina:5 major cell types arranged in layers:

Answer 28

Photoreceptors (Rods, Cones, Opsins, Glutamate)
Bipolar (ON and OFF)
Ganglion (ON, OFF, Transient, Sustained)
Amacrine
Horizontal

Question 29

Two specialized sites in the retina:

Answer 29

Fovea

Optic Disk

Question 30

Ganglion cell contribution to low-level processing by enhancing/emphasizing:

Answer 30

Brightening And Dimming,
Contrast,
Movement,
Relative Brightness (deconstructing visual environment into basic attributes)