Sight

Question 1

What is the wavelength range that our visual receptors are able to perceive?

Answer 1

Approx. 400 to 700 nanometers

Question 2

Where do we have the highest density of photoreceptors?

Answer 2

The fovea.

Less photoreceptors as you move away from the fovea along the retina.

Question 3

What are the three cell layers of the retina? Order them according to which receives light first.

Answer 3

1. Photoreceptor cell layer
2. Bipolar cell layer
3. Ganglion cell layer

Question 4

Once stimli is received via light in the photoreceptor cell, what needs to happen to cause an action potential?

Answer 4

First a hyperpolarizing, followed by a depolarizing of the memebrane potenial of a ganglion cell

Question 5

What colours are the short, medium, long wavelength cones?

Answer 5

short = blue
medium = green
long = red

Different complexity of wavelength stimulates these cones and action pot

Question 6

What is Deuteranopia?

Answer 6

A form of colourblindness.

The green cones are absent.

Question 7

What is Protanopia?

Answer 7

The red cones are absent.

Question 8

What is each ganglion cell responding too?

similar to frequency and the basiliar membrane

Answer 8

They are responding light stimulation coming from a specific location in the world onto the retina

Question 9

What is retinotopic?

Answer 9

It refers to the mapping of visual stimuli from the retina onto specific locations in the brain.

Question 10

Does light falling on photoreceptors lead to increased activity in ganglion cells?

Answer 10

No necessarily. It depends on connections of the photoreceptors on the bipolar cells which determines whether that light is going to be inhibitory or excitatory

Question 11

What is the pathway to the LGN called?

Answer 11

The Retinogeniculate Pathway.

Question 12

What does the Lateral Geniculate Neucleus do? And how many layers does it have?

Answer 12

• The LGN functions to relay visual information from the retina to the visual cortex.
• 6 layers

Question 13

What are the inner two layers of the LGN refered to as? What are they most responsive to?

Answer 13

• Magnocellular layers.
• Most responsive to rapid changes in patterns of light (MOVEMENT)

Question 14

What are the outter four layers of the LGN refered to as? What are they most resposive to?

Answer 14

• Parvocellular layers.
• Responsive to cone combination (COLOUR VISION)

Question 15

After the LGN where are is the information processed?

Answer 15

The primary visual cortex.

Question 16

Name another place besides the PVC that visual information can be processed. What kind of information is it?

Answer 16

• The suprachiasmatic nucleus (SCN)
• Provide signals about day time or night time (circadian)

Question 17

What does the Suprachiamatic nucleus inform? What is it’s function

Answer 17

• This area registers the total amount of light in ones environement.
• This results in certain hormones being released which allows for our behaviour to match our environment
• ‘Biological clock or circadian oscillator

Question 18

Is the SCN involed in your concious visual perception of the the world around you?

Answer 18

No. This is circadian type clock based on light regestering.

Question 19

When is a bionic eye useful, and when won’t it work?

Answer 19

• Useful when photoreceptors are damaged.
• Must have intact ganglion cells
  *

Question 20

What are the major techological components of a bionic eye?

Answer 20

1. Camera
2. Receiver
3. Implant

Question 21

What is a receptor feild?

Answer 21

The output from a ganglion cell depends on the pattern of inputs i.e a group of photoreceptors

Question 22

Where do 80% of the ganglion cell fibres feed through to?

Answer 22

The Lateral Geniculate Neucleus.