Vision, Touch & Pain

Question 1

what are the different levels of hierarchical organisation?

Answer 1

1. receptors
2. thalamic nuclei
3. primary sensory cortex
4. secondary sensory cortex
5. association cortex

Question 2

what happens at each stage of the hierarchical organisation?

Answer 2

1. each level gathers and analyses information processed

2. neurons respond to stimuli with great specificity and complexity

Question 3

Main parts of the eye

Answer 3

1. Pupil
2. Iris
3. Lens
4. Retina
5. Fovea
6. Blind spot

Question 4

what is light

Answer 4

electromagnetic wave/spectrum - 400 to 700nm

Question 5

stages of light through the eye…

Answer 5

1. pupil
2. iris (dilation, constriction)
3. lense
4. retina
   5.

Question 6

what is binocular disparity

Answer 6

where your brain gauge the difference in images opposition on the two retinas

= depth perception

Question 7

bundle of axons at the back of the eye =

Answer 7

blind spot

Question 8

what are the 5 different types of neurons?

Answer 8

1. photoreceptors (cones and rods)
2. horizontal cells
3. bipolar cells
4. amacrine cells
5. retinal ganglion cells

Question 9

more rods or more cones?

Answer 9

rods = more sensitivity

Question 10

what is the function of the fovea and why are there no rods?

Answer 10

only cones = specialises in high-acuity vision = result is small details

Question 11

90% of axons of ganglion cells are part of what - pathway

Answer 11

retina-geniculate-straite pathway

Question 12

what happens to axons during the retina-geniculate-straite pathway?

Answer 12

1. axons from the ganglion cells leave the back of the eyeball (optic nerve)
2. cross the optic chiasma (only left/right side)
3. pass through the lateral geniculate nucleus (in the thalamus
4. primary visual cortex (L or R hemisphere)

Question 13

what does the dorsal stream do with visual information?

Answer 13

interprets spatial information (location/motion) - “where”: shark

Question 14

what does the ventral stream do with visual information?

Answer 14

interprets objects characteristics (colour/shape) - “what”: tennis ball

Question 15

how do we perceive edges?

Answer 15

lateral inhibition

Question 16

what are saccades?

Answer 16

rapid eye movement = without this reinal images disappear after a few seconds (colour, high-acuity, wide-angle)

Question 17

what do saccades generally do?

Answer 17

enable neurons to gather information and input about your perception

Question 18

what is component processing (colour perception)?

Answer 18

3 types of cones:

- photopigment in each type of**

Question 19

what is colour blindness?

Answer 19

deficiency of absence of photopigment

Question 20

what is component processing/trichromatic theory?

Answer 20

3 different types of cones:
- the type of photopigment in each type of cone makes it responsive to certain types of wave lengths and certain colours - Short = blue, medium = green, long = red

Question 21

opponent processing theory

Answer 21

neurons respond in opposite directions to complementary colours (red-green, blue-yellow, black-white)

Question 22

what is Colour constancy

Answer 22

ability to perceive colours as relatively constant over varying illuminations (i.e. light sources; cloudy day vs sunny day)

Question 23

what other than brighten, size and shape constancy impacts colour constancy?

Answer 23

our perception: top-down processing

Question 24

what are the two main streams in the visual system

Answer 24

1. dorsal stream

2. ventral stream

Question 25

the binding problem (perception of a single object)

Answer 25

sensory info converges into areas sensitive to certain stimulus characteristics

Question 26

criticism of the binding problem

Answer 26

would need neurons that code whole objects (grand-mother neurons)
= environment too complex to have neurons for each single object

Question 27

simultaneous activity for object perceptions …

Answer 27

binding of a percept requires simultaneous activity in the brain areas/neurons involved in processing objects

= simultaneous neurons process the object at one time

Question 28

what does pathway I measure

Answer 28

• touch and proprioception (position of the body)

Question 29

route of pathway I

Answer 29

1. touch
2. brain stem (cross over before)
3. thalamus
4. primary somatosensory cortex (SI)

Question 30

what does pathway II measure?

Answer 30

• Pain and temperature

Question 31

How does Pathway II measure pain and temperature?

Answer 31

1. Pain/temp
2. Neuron to spinal cord
3. neurons to thalamus
4. SI, SII and posterior parietal cortex

Question 32

what neurotransmitters are are released at a synapses in the spinal cord?

Answer 32

mild pain: glutamate

strong pain: glutamate and substance P

Question 33

what are the 2 pain pathways to the brain?

Answer 33

1. thalamus-somatosensory cortex pathway

2. limbic system - prefrontal cortex pathway

Question 34

what does the thalamus-somatosensory cortex pathway convey

Answer 34

sensory aspects of pain

Question 35

what does prefrontal cortex pathway react to

Answer 35

emotional quality associated with pain

• Pathways active if you watch someone experiencing pain
• Activity of cingulate cortex reduced in pain relieve due to hypnosis or placebos

Question 36

what do opiates like morphine do to alleviate pain?

Answer 36

block the release of Substance P

Question 37

what is the body own opiate? and what do they do?

Answer 37

endorphins
Endorphins inhibit the realise of substance P in the spinal cord from neurons that carry the pain message → gate-control-theory (imagine fluid gates opening, which is pain, other things can shut the gate which reduce the feeling of pain and endorphins)