Lecture 10 - Sensation and perception and human neuropsychology

Question 1

Sensation

Answer 1

Sensation = the act of receiving information from the environment
- you have sensory organs whose purpose is to receive the energy that is out there and they engage in sensation

Question 2

Perception

Answer 2

Perception = the interpretation of the information you are receiving

Question 3

How many receptors in the retina must go into 1 million fibres in the optic nerve?

Answer 3

127 million

Question 4

Neural implementations

Answer 4

Neural implementations (no matter what sensory system we are talking about - auditory, visual, somatosensory)
1 - Sensory organs absorb energy
2- Energy is TRANSDUCED into a neural signal
3- The neural signal is sent throughout the brain where further processing takes place

Question 5

Vision neural implementation

Answer 5

Rods and cones (photoreceptors) in the eyes absorb the energy from the environment and convert it into a neural signal and then this neural signal is sent throughout the brain

Question 6

Why study vision?

Answer 6

most studied system, we know the most about how it is constructed and how it works compared to other systems, study it because we are highly visual creatures ourselves (up to 1/2 the human brain is involved in visual information processing)

Question 7

Light and the electromagnetic spectrum

Answer 7

lots of energies that are out there and coming into the eye but the eye is only sensitive to an incredibly small portion of these energies known as visible light

Question 8

Wavelength determines

Answer 8

the colour that we see

Question 9

Amplitude determines

Answer 9

the brightness that we see

Question 10

Cornea

Answer 10

Transparent outer ayer of the eye
Has some focusing ability
Helps the image focus on the retina
Behind the cornea is the anterior chamber

Question 11

Choroid

Answer 11

Vascular layer of eye
Vascular tunic is another name
Eye is structure that requires a blood supply as the blood will provide nutrients and keep the eye alive and will take waste away from the eye, layer of blood cells that keeps it alive, do not want it on the cornea as we need it to be transparent and we do this through humours

Question 12

Vitreous humour

Answer 12

Keeps eye structures alive
fills space between lens and retina
Chamber filled with fluid which acts like blood which filters and gets rid of waste
The inner layer needs to be kept alive and it cannot have blood cells so there is a gelatinous material in the anterior chamber and in the posterior/vitreous chamber which provides nutrients to the parts of the eye where you do not want to interfere vision with the blood supply
helps to maintain the shape of the eye ball
aqueous humour provides nutrients to the cornea

Question 13

Iris

Answer 13

Iris is the muscle and gives the characteristic colours of the eyes
Can contract or expand to allow less or more light in respectively
Bright day = pupils small since iris contracts
Dark room = pupil size large

Question 14

Pupil

Answer 14

The distance between the ends of the iris

Question 15

Lens

Answer 15

Hard but flexible structure that allows you to engage in the process of accommodation so you can look at something close in focus and then look at something further away also in focus
Accommodation
Lens is attached to muscle sea dad the ability to change shape but as you get older, the lens loses its flexibility which may require glasses
Cataracts is the clouding of the lens and causes you not to see and there is surgery done to replace the lens
Congenital cataracts is where you are born with cataracts and effectively blind from birth but there are modern day techniques that have been developed to remove the lens
All of the sensory systems have a critical period for development and information must be processed perfectly by these systems otherwise they do not develop perfectly

Question 16

Retina

Answer 16

Location of the photoreceptors known as rods and cones
Three layers
Photoreceptor layer has rods and cones which both do different things and they are the structures that are involved in transfusing information, take electromagnetic energy and convert it into a neural/electrical signal and send it onto the next start which is the bipolar cell layer which does their thing and then add a little bit more information and then send it off to the ganglion cell layer that do their thing
There are 127 million rods and cones and only 1 million ganglion cell axons that come out of the brain to form the optic nerve

Question 17

3 layers of the retina

Answer 17

Photoreceptor layer (rods and cones)
Bipolar cell layer
Ganglion cell layer

Question 18

Rods

Answer 18

No colour (black and white)
Night time
Low resolution

Question 19

cones

Answer 19

Show colour
Day time
High resolution

Question 20

Distribution of rods and cones

Answer 20

Most of the cones (7 million) are at 0 degrees/fovea
When you are bringing in and focusing on an image you are bringing that image to fall on the fovea of the retina where all the cones are located, the 120 million rods are scattered across the periphery and there are almost none at the fovea and this is why at night you do not look directly at a faint star and you should instead look at it from the side

Question 21

Blind spot

Answer 21

About 16-18 degrees from the fovea where there are no photoreceptors at all

Question 22

Optic nerve

Answer 22

The job of the optic nerve is to transfer visual information from the retina to the vision centres of the brain via electrical impulses.

Question 23

Outer layer of the eye

Answer 23

Cornea

Question 24

Middle layer of the eye

Answer 24

Choroid

Question 25

Inner layer of the eye

Answer 25

Vitreous humour
Iris 
Pupil 
Lens
Retina