Vision Lecture

Question 1

What is the journey through the visual system?

Answer 1

Eye (retina) -> primary visual cortex -> rest of cortex

Question 2

What can light be defined as?

Answer 2

Waves of electromagnetic energy that are between 380 and 760 nanometers in length

Question 3

What animal can see infared waves?

Answer 3

Rattlesnake - see warm blooded prey

Question 4

Importance of wavelength

Answer 4

Perception of colour

Question 5

Importance of intensity

Answer 5

Perception of brightness

Question 6

Iris

Answer 6

Bands of contractile tissue that regulate the amount of light reaching the retina

Question 7

Pupil

Answer 7

Hole in the centre of iris that allows light to enter the retina

Question 8

What is the amount of light reaching the retinas regulated by?

Answer 8

The irises

Question 9

Characteristic couloir of eyes is given by

Answer 9

Iris

Question 10

The adjustment of pupil size in response to changes in illumination represents

Answer 10

A compromise between acuity and sensitivity

Question 11

Sensitivity is

Answer 11

The ability to detect the presence of dimly lit objects

Question 12

Acuity is

Answer 12

The ability to see the details of the objects

Question 13

When is image sharper and focus deeper?

Answer 13

When the pupils are constricted

Question 14

The function of the lens

Answer 14

Focuses light on the retina

Question 15

Function of ciliary muscles

Answer 15

Alter the shape of the lens as jeeded

Question 16

What is accommodation?

Answer 16

The process of adjusting the lens to bring images into focus

Question 17

What is binocular disparity?

Answer 17

The difference in the position of the same image on the two retinas - greater for closer objects that for distance objects

Question 18

The function of the retina

Answer 18

Converts light to neural signals, conducts them toward the CNS, and participates in the processing of the signals

Question 19

Two visual problems of inside out arrangement

Answer 19

Incoming light is distorted by the retinal tissue through which it must pass before reaching the receptors
For the bundle of cell axons to leave the eye, there must be a gap in the receptor layer (blind spot)

Question 20

Photo pic vision has

Answer 20

Good light, high acuity, colour, cone mediated

Question 21

Scotopic vision has

Answer 21

Dim light, low acuity, high sensitivity, lacks colour, rod mediated

Question 22

What can be found at the fovea

Answer 22

Cones not rods

Question 23

Parvocellular layers

Answer 23

4 top layers, colour, fine pattern details to stationary or slowing moving objected. Input from cones

Question 24

Magnocellular layers

Answer 24

2 bottom laters of retinal ganglion cells, movements, majority input provided by rods

Question 25

3 functions of the lateral geniculate nucleus (thalamus)

Answer 25

1. Each of the size layers receives input from all parts of the contralateral visual field 2. Three layers receives input from one eye and three from the other 3. Most of the LGN that project to the primary visual cortex terminate in the lower part of the cortical layer producing a characteristic stripe

Question 26

What is the receptive field?

Answer 26

Area of the visual field within which it is possible for a visual stimulus to influence the firing of that neuron

Question 27

Impacts of hypoxia

Answer 27

Cannot identify or copy objects Difficulty in grasping and reaching towards objects Lesions in posterior parietal cortex

Question 28

What is hemi spatial neglect?

Answer 28

Lack of awareness of the side of space opposite to the side of a brain lesion

Question 29

Ways of assessing hemi spatial neglect?

Answer 29

Pen and paper tasks including cancellation tasks, line dissection and figure copying tasks