Ch.9, Sensation, START OF FINAL **

Question 1

Difference between sensation and perception

Answer 1

sensory info is detected by a sensory receptor, which is a specialized neuron that responds to a specific stimulus
perception: the way sensory info is organized, interpreted, and experienced, subjective, nothing is ever 100% accurate

Question 2

Illusions

Answer 2

result of brain misinterpreting a sensory stimulus

Question 3

Neural relay, visual (1-3)

Answer 3

1. Rods cones
2. Lateral geniculate nucleus in the thalamus (LGN)
3. V1, primary visual in occipital

Question 4

Auditory relay, 1-5

Answer 4

1. inner hair cells/auditory receptors
2. medulla in the hindbrain
3. inferior colliculus in the tectum (midbrain part of the brainstem)
4. medial geniculate nucleus (thalamus) relay
5. A1, primary auditory, cerebral cortex

Question 5

Somatosensory relay

Answer 5

1. somato receptors
2. spinal cord
3. brainstem
4. thalamus
5. S1, typically in the cerebral cortex

Question 6

Somatosensation

Answer 6

includes proprioception: where your body is in space
vestibular: balance
nociception: pain
thermoception: temp

Question 7

function of sensory receptors

Answer 7

transduce environmental energy into neural activity

Question 8

3 key variables impacting sensory receptors

Answer 8

1. receptive field: how much of the environment a receptor can take in; aids in localization of sensations in space: forms cortical paterns/maps to make a person’s reality
2. receptor density: higher density in an area = greater acuity of that area
3. receptor sensitivity: different types of receptors are more sensitive to certain stimuli than others

Question 9

neuron discharge rate

Answer 9

number of APS fired per second, can encode stimulus intensity or sometimes qualitative changes

Question 10

Topographic map

Answer 10

each sensation is processed in its own region of neocortex, a spatially organized neural representation of the body or sensory world

Question 11

why are human lips and hands more dexterous

Answer 11

more cortex region devoted to these regions

Question 12

fingertip vs back sensitivity

Answer 12

fingertips have 100x more recetors than back, and m,ore CNS neurons are devoted to receiving this sensory info

Question 13

electromagnetic radiation

Answer 13

stream of photons; mass-less particles that travel in waves

Question 14

sense that has the most brain area dedicated to it

Answer 14

vision

Question 15

visible light

Answer 15

400 to 700 nanometers
longer the wave: lower the energy, more safe

Question 16

two animals that detect light in ultraviolet

Answer 16

butterflies and bees

Question 17

sclera, retina, optic disc, cornea, lens pupil, fovea

Answer 17

sclera: forms the eyeball, whiote of the eye
Cornea: clear outer covering keeps out dirt , BENDS LIGHJT FIRST
Retina: light energy intiates neural activity, fovea is area of highest acuity, densest distribution of photoreceptors specialized for color
optic disc: where blood vessels enter the eye and axons that form the optic nerve leave the eye, no receptors, blind spot
LENS: BENDS LIGHT AFTER CORNEA

Question 18

Retina

Answer 18

light sensitive surface at the back of the eye consisting of neurons and photoreceptive cells

Question 19

photoreceptors

Answer 19

specialized retinal neurons transduces light into neural activity

Question 20

differences between rods and cones

Answer 20

rods: cylindrical outer segment, longer, more of them, sensitive to night light, night vision, have the same light absorbing pigment in their outer segment
cones: tapered outer segment, mediate color vision and acuity (fine detail), only responsive to bright light, fovea has cones only, each cone contains one of three pigments

Question 21

visual illuminence and age

Answer 21

-as we age, we rely on rods more than cones=less acuity
-worse night vision
50% reduction in dim light acuity from age 20-40
-lens yellows with age: takes less light in
cornea doesn’t allow as much light

Question 22

3 types of cone pigments, color and wavelength

Answer 22

s cones: short wavelength, blue: much less of these
m cones: medium wavelength, green
l cones: long wavelength, red
-each cone can detect more than what is specific to it, but these are what they are most sensitive to

Question 23

what quantity of visual recptors are rods?

Answer 23

95%

Question 24

muller cell

Answer 24

glial cell, funnels light to the back of the retina

Question 25

axons of ganglion cells

Answer 25

bundle together to form optic nerve

Question 26

retinal ganglion cells, two types

Answer 26

sensory neurons carrying info brain
Magnocellular Cell:
magno means large, receive input from rods, low acuuity, night vision, sensitive to light and moving stimuli, distributed throughout the retina like rods
Parvocellular cell:
parvo means small, receives inputs from cones, high acuity, color vision, detailed, concentrated at certain areas like cones

Question 27

LGN layers in the thalamus

Answer 27

layers 1-2
magnocellular layers
recieve input from magnocellular cells (rods)
layers 3-6
parvocellular layers
receive input from parvoceullar cells (cones)

Question 28

optic chiasm and optic nerve

Answer 28

optic chiasm: junction, where they cross, outside brain,
optic nerve: cranial nerve 2

Question 29

2 routes for visual information

Answer 29

conscious: geniculostriate system
LGN–striate cortex (in layer IV specifically, bc that layer is afferent)
unconscious: tectopulvinar system
superior colliculus (tectum, midbrain, brainstem) –pulvinar in the thalamus, reactions

Question 30

why does striate cortex have so many stripes

Answer 30

bc the huge layer IV

Question 31

optic radiations

Answer 31

white matter tracts, axons from the neurons in the lateral geniculate nucleus to the primary visual cortex

Question 32

at the optic chiasm, 60% of the axons from the optic nerve cross or

Question 33

rule for temporal and nasal retinas

Answer 33

temporal: stays epsilateral, always on the same side
nasal: always goes contralateral, always on the opposite side

Question 34

Hemifields

Answer 34

hemifield is US perceiving the visual field: OUR PERCPETION

Question 35

Diagram how light moves from the left hemifield of left eye

Answer 35

1. left nasal retina
2. crosses to the LGN on the right side
3. Proceeds to right V1

Question 36

Diagram how light moves from the left hemifield of right eye

Answer 36

1. temporal retina in right eye
2. stays epsilteral, right LGN, right V1

Question 37

What does each optic nerve receive before the chiasm?

Answer 37

before chiasm, each optic nerve has info from both visual fields BUT only one eye

Question 38

what does each optic tract receive after the chiasm?

Answer 38

after chiasm, each optic tract has info from 1 visual field but both eyes

Question 39

Right optic nerve damaged

Answer 39

only getting info from left eye (bc right optic nerve is connected to right eye) but from both visual fields (the left and the right), bc each eye can independently see both visual fields

Question 40

left optic nerve damaged

Answer 40

only getting info from right eye, (bc left optic nerve is connected to left eye), but still getting info from both visual fields since each eye can independently see both fields

Question 41

Left optic tract damage

Answer 41

if left optic tract is damaged, only getting info from left visual field AND NOT THE RIGHT (bc the right would cross over to the left),

Question 42

right optic tract damage

Answer 42

if right optic tract is damaged, only getting info from right visual field, NOT LEFT, bc left would cross over to the right

Question 43

function of iris

Answer 43

iris opens and closes to allow more or less light into the pupil