Visual System

Question 0

What is the difference between visual field and retinal field?

Answer 0

Visual field- what the patient sees

Retinal field- what region of the retina onto which the image is projected.

Question 1

What effect do pupils have on images as they pass through it?

Answer 1

Pupil inverts image

Question 2

What structure of the retina is responsible for color and high resolution/ detail.

Answer 2

Cones

Question 3

What area of the retina is responsible for low resolution and movement?

Answer 3

Rods

Question 4

What region of the retina is one blind?

Answer 4

Blind spot- point of exit of ganglion cell axons

Question 5

Which retinal neuron gives rise to fibers of the optic nerve?

Answer 5

Ganglion cell axons

Question 6

Name three structures in which primary visual fibers terminate

Answer 6

Hypothalamus suprachiasmatic nucleus- circadian rhythms
Amygdala- transmission of emotionally significant images
Lateral geniculate body- visual info: achieve a three-dimensional representation of object space as well as obtain information for controlling the precision optical system of the visual modality.

Question 7

What is retinotopic organization?

Answer 7

The neurons in primary visual cortex are organized “retinotopically”. This means that different parts of the visual field (what you can see) are laid out in an organized manner in the visual cortex, and this retinotopic map is repeated several times in the early visual areas.

Question 8

Describe the location and function of secondary and tertiary visual areas.

Answer 8

Located in brodman areas 18-19.

Color and stereopsis.
V5/MT (middle temporal area)
Movement: direction and velocity

MST (medial superior temporal area)
- perceived motion of stationary targets as observer moves

Question 9

What happens with a right optic nerve lesion?

Answer 9

Complete blindness in the right eye. Unilateral blindness

Question 10

What happens with a optic chiasm lesion?

Answer 10

blindness in the right half of the right eye and left half of the left eye. Bitemporal hemianopsia

Question 11

What happens with a right optic tract lesion?

Answer 11

Blindness is the left half of both of the right and left eyes. Left homonymous hemianopsia.

Question 12

What happens with a geniculocalcarine tract lesion?

Answer 12

No one knows

Question 13

What happens with a primary visual cortex lesion?

Answer 13

Retention of ability to determine object location by vision but denial of blindness.

Question 14

What happens with a fusiform face area lesion?

Answer 14

Prosopagnosia. Loss of ability to name faces.

Question 15

What is the “what” system.

Answer 15

Midget parvocellular retinal ganglion cells.
Identification of visual image.
Processed as part of visual stream.

Question 16

What is the “where” system

Answer 16

Parasol magnocellular retinal ganglion cells.
Location and movement of visual image.
Processed as part of dorsal steam.

Question 17

Visual agnostia is what?

Answer 17

Loss of secondary and or tertiary visual cortex especially on one side that results in the inability to recognize objects based on vision or know what an object is used for.

Question 18

Anton syndrome is what?

Answer 18

Loss of primary visual cortex and vision. Denial of loss.

Question 19

What is Charles bonnet syndrome?

Answer 19

Visual hallucinations associated w age and reduced vision. (Amusing or disturbing but not emotional).