Lecture 11

Question 1

Fovea

Answer 1

המרכז שבו האור מתקבץ ונותן התמונה הכי חדה, סיבים מקובצים יחד בדחיסות גדולה
The fovea is fixed and is found only in the nasal hemiretina.
There are only cones in the fovea (low sensitivity, high acuity)

Question 2

Blind spot

Answer 2

בנקודה זאת אין תאי עצב שמפרשים את הפוטונים של האור, ולכן דברים שנופלים עליה אנחנו לא רואים. אנחנו לא מרגישים אותה בגלל שכל עין מפצה על נקודת העיוורון של העין האחרת.

Question 3

Binocular Disparity

Answer 3

The brain can gauge the difference in the image’s position on the retina:
* Greater disparity = closer
* Lesser disparity = farther

Question 4

מה הן חמשת סוגי תאי העצב במערכת הראייה?

Answer 4

1) photoreceptors
2) horizontal cells
3) bipolar cells
4) amacrine cells: inhibition
5) retinal ganglion cells: משם לסיב האופטי ואל נקודת העיוורון.

Question 5

Rods - night or day light?

Answer 5

night

Question 6

Cones - night or day light?

Answer 6

day

Question 7

What do the rods and cones do?

Answer 7

מפרשים את האור ומתרגמים אותו לפעילות חשמלית.

Question 8

What are the three types of cones?

Answer 8

1) Blue = short wavelength = Tritan
2) Green = medium wavelength = Deutan
3) Red = long wavelength = Protan

Question 9

Photopic vision

Answer 9

occurs when there is plenty of light (=cones)
Low sensitivity & high acuity
Maximum sensitivity is around 650 nm.

Question 10

Scotopic vision

Answer 10

occurs when light source is very dim (=rods)
High sensitivity & low acuity
Maximum sensitivity is around 500 nm.

Question 11

Purkinje effect

Answer 11

Shift from bright (photopic vision) to dim light (scotopic vision) produces the Purkinje effect.
In bright light: yellow and red are the brightest.
In dim light: green and blue are the brightest.

Question 12

Retina-geniculate -striate pathway

Answer 12

Optic chiasm - LGN in the thalamus - superior colliculus (visual reflexes, coordination, eye-head movement, fight or flight) - optic radiation - primary visual cortex

Question 13

Magno-cellular layers

Answer 13

There are 2 of them in the LGN.
Respond to objects in motions & low spatial frequencies.

Question 14

Parvo-cellular layers

Answer 14

There are 4 of them in the LGN.
Respond to fine details.

Question 15

V1

Answer 15

Brodman’s area 17.
נמצא בגדות של ה- calcarine fissure.
פרשנות.

Question 16

Retinotopic organization

Answer 16

Specific columns of neurons correspond to specific areas of the retina and thus the visual field.

Upper half of visual field represented below the calcarine. Lower half of visual field represented above the calcarine.

Disproportionally large representation of the fovea in posterior end (occipital pole).

Question 17

Rceptive fields

Answer 17

שדה של תאי עצב הנמצא במוח המיועד עבור קידוד אינפורמציה ספציפית ומיוחדת במרחב.
Most V1 neurons are orientation selective, meaning that they respond strongly to lines, bars, or edges of a particular orientation (e.g., vertical) but not to the orthogonal orientation (e.g., horizontal).

Question 18

Simple cells’ selectivity and location

Answer 18

Orientation, position
Brodman’s 17

Question 19

Complex cells’ selectivity and location

Answer 19

Orientation, motion, direction
Brodman’s 17 & 18

Question 20

Hypercomplex cells’ selectivity and location

Answer 20

Orientation, motion, direction, and length
Brodman’s 18 & 19

Question 21

Ocular dominance columns

Answer 21

Stripes of neurons in the visual cortex that respond preferentially to input from one eye or the other.

Question 22

Orientation columns

Answer 22

stimuli from similar spatial orientation.

Question 23

Dorsal stream

Answer 23

Interprets spatial information (location/motion: Where)

Shape, movement and location – necessary for action on the stimulus.

Primary visual cortex – dorsal prestriate cortex –posterial parietal cortex.

Question 24

Ventral stream

Answer 24

Interprets object characteristics (color/shape: What)

Shape, depth, color – necessary for recognition

Primary visual cortex – ventral prestriate cortex –inferotemporal cortex

Question 25

Monocular vision loss/ left anopia

Answer 25

Lesion on the left optic nerve
מפסיקים לראות בעין אחת.

Question 26

Bitemporal hemianopia

Answer 26

Lesion on the optic chiasm
פוגעת בחלק הטמפורלי של שדה הראייה ולכן מאבדים את האינפורמציה מהצדדים ורואים רק המרכז.

Question 27

Contralateral homonymous hemianopia

Answer 27

Lesion after the optic chiasm
פגיעה בצד ימין במוח תגרום ל:
פגיעה בשדה הראיה השמאלי בשני העיניים.
Loss of vision on the right nasal and left temporal field.

Question 28

Contralateral superior quadrantopia

Answer 28

Lesion on of the optic tracts

Question 29

Central scotoma

Answer 29

פגיעה ברטינה בתוך גלגל העין מאבדים את הראייה במרכז, אין רצפטורים בנקודה הזאת בשביל לקלוט מידע.

Question 30

Cortical blindness

Answer 30

Blindness as a result of lesion to V1 rather than retina or optic nerve. תמרון יכול לעזור

Question 31

Blindsight

Answer 31

subject responds to visual stimuli in the blind area, with no awareness of them.
Visual pathways to cortex bypass V1 Via brain stem and thalamus. Transmit some aspects of visual information but does not reach awareness.

Question 32

Akinetopsia

Answer 32

Motion blindness, inability to perceive movement, V5 lesion.

Question 33

Visual prosopagnosia

Answer 33

אי יכולת לזהות פרצופים.

Question 34

Object agnosia and face agnosia.

Answer 34

Object agnosia: sees only the faces.
Face agnosia: sees only the objects.
There is a double dissociation between face and non-face processing.

Question 35

V5

Answer 35

Motion detection
responds even to illusory motion

Question 36

V3

Answer 36

Dynamic form, object in motion, coherent motion.