sensation and perception Flashcards

1
Q

sensation

A

describes the registration and initial encoding of sensory information

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2
Q

perception

A

refers to how the brain organizes sensory information into meaningful representations

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3
Q

retina

A

several layers of cells at the back of the eye

begin initial representation of visual work

extension of the brain

retinal tissue is derived from the neural tissue during embryological development

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4
Q

cones

A

colour
large size
conical shape
bright light
central location
opsins are red, green and blue

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5
Q

rods

A

black/white
small size
narrow shape
dim light
periphal location
opsin is rhodopsin

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6
Q

parallel processing

A

begins with the photoreceptor cells in the retina

rods and cones are an input response

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7
Q

pigments in the rods and cones

A

absorb light energy and transform it into electrochemical energy used in the nervous system

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8
Q

how many rods and cones do we have

A

120 million rods
6 million cones

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9
Q

what causes the release of NT’s in the photoreceptors

A

the cascade of chemical changes inside the rod/cone which changes membrane depolarization

this signals to the next layer of cells within the eye

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10
Q

what are the 3 types of ways rods and cones differ

A

types of pigments
distribution across the retina
interaction with ganglion cells

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11
Q

pigment in rods

A

rhodopsin: saturated in broad daylight therefore rod system will not function

sensitive to very small amounts of light

not sensitive to fine detail because so many feed into one ganglion cell

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12
Q

pigments in cones

A

each contain a different pigment sensitive to a different wavelength in the visible light spectrum

blue (short wavelength), green (medium wavelength) and red (long wavelength)
- pattern of activity in these receptors enables the variation in colour

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13
Q

cones retinal distribution

A

densely in the fovea

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14
Q

rods retinal distribution

A

located in the periphery

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15
Q

fovea

A

main area of focus for vision

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16
Q

rods interaction with ganglion cells

A

many rods feed into a ganglion cell

feature makes it respond to low levels of light

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17
Q

cones interaction with ganglion cells

A

few cones feed into ganglion cell

allows for more fine detail - cannot function under low light conditions

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18
Q

blind spot

A

where optic nerve leaves the eye

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19
Q

ganglion cells

A

cell bodies located in the retina, axons stretch out from retina

output response from eye to brain

two main types of cells M cells and P cells which both form functional pathways

send their input to different destinations in the brain

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20
Q

M cells

A

magnocellular = large

responsive to coarse pattern and detect rapid motion

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21
Q

P cells

A

parvocellular = small

preserve colour information

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22
Q

small bistratified

A

has unique projection to the thalamus

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23
Q

receptive fields

A

the specific region of visual space a cell responds to

when the eye is stationary, light from a particular location in space only falls on a specific part of the retinal surface - this stimulates specific subgroups of rods or cones which send messages to specific ganglion cells

light must be absorbed by a specific rod or cone for that photoreceptor to respond

the brain knows where light has struck by knowing which ganglion cells are excited

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24
Q

centre-surround structure

A

what the receptive fields of retinal ganglion cells have

light in a particular spot in visual space will excited a ganglion cell, but light in the donut shape area encirculating it will enhibit it - can also work in the opposite manner

this enhances contrast (edges and borders of objects)

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25
Q

tectopulvinar pathway

A

allows us to oriente important visual info quickly

fast-acting

sensitive to motion and apperances of novel objects in visual periphery

recieves most its input from M ganglion cell

sends visual info from retina directly to th superior colliculus

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26
Q

superior colliculus

A

pathway that extends to the pulvinar nucleus in the thalamus and to cortical areas that processes info about visual motion

sends projections to motor regions that control eye and head movements

info leaving optic nerve can terminate here

fast-acting

not sensitive to fine detail

site for integration of auditory and visual senses together

allows for orientations of eyes to periphery to be brought to central vision and then go to geniculostriate pathway

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27
Q

tectum

A

in midbrain

includes inferior colliculus (auditory)
superior colliculus (visual)

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28
Q

the geniculostriate pathway

A

extends to lateral geniculate and then to striate cortex

90 percent of optic nerve fibers project to this pathway

enables our consious experience to seeing

axons terminate in the lateral geniculate nucleus of the thalamus

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29
Q

lateral geniculate nucleus

A

continues info to the primary visual (striate) cortex

enables perception of colour

info from the right side of both retina is sent to the LGN on the right side of the brain and vice versa

has six main layers stacked on top of one another and then folded into a knee like shape

each layer recieves input from only one eye, but all layers recieve info from the contralateral visual field

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30
Q

optic tract

A

ones the nerve fibers cross at the optic chiasm they are reffered to as this

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31
Q

koniocellular layers

A

small cell layers in-between the main LGN layer

receive input from the small bistratified ganglion cells and the superior colliculus

relevance to blindsight

32
Q

magnocellular layer

A

obtains input from M cells

detects motion

33
Q

parvocellular layers

A

obtain input from p cells

detect colour and detail

34
Q

retinotopic map

A

each main layer in the LGn contains this of half the visual field, laid put by the retina itself

ensures that info does not get jumbled up when it reaches the LGN

fMRI studies show this

35
Q

where does visual info go once it passes through the LGN

A

Primary visual cortex (striate cortex)

36
Q

Primary visual cortex (striate cortex)

A

projections from the LGN to here maintain their spatial location

not much info from the periphery reaches here, mostly dedicated to the center

37
Q

cortical magnification factor

A

describes the mm’s of cortical surface that are devoted to one degree of angle of the visual world

higher for the fovea compared to the periphery

38
Q

why is the primary visual cortex considered striate

A

because the distinct layers make it appear to be striped

39
Q

cells of the striate cortex

A

not tuned to light, responds to bards of light oriented in different ways

simple cells
complex cells
hyper-complex cells

40
Q

simple cells

A

respond to bard of different orientations

excitatory centre, inhibatory surround - only fire is bar is oriented in a certain way

41
Q

complex cells

A

respond best to certain line orientations

less picky about where exactly the line is located - do not have an on and off region

show preference for direction of movement

42
Q

hyper-complex cells

A

or end stop cells

prefer lines of certain lengths

43
Q

columns in the striate cortex

A

cells that prefer a given line orientation are grouped together forming orientation columns

44
Q

ocular dominance columns

A

are made of cells segregated according to which eye sends them input

45
Q

hypercolumn

A

contains cells that are all tuned to respond to stimulation at a particular spatial location

have blobs within - involved in coding colour info

each responds to a different retinal location

across all, all orientations in space are represented

referred to as ice cude tray model

46
Q

importance of having two eyes

A

helps with depth perception as it is computed by the brain

info from both eyes is integrated

47
Q

binocular disparity

A

the image that falls on each retina is different as the eyes are positioned in different locations
- more different when eyes are clos, then when they are far

the brain uses this info to determine depth

some cells in the striate cortex are especially tuned to certain amounts of binocular disparity
- different cells code for different amounts

response relies of context - can modulate

48
Q

cerebral achromatopsia

A

posterior ventral cortex damage and altered colour perception

report the world in shades of gray

49
Q

V4 area

A

colour

cells demonstrate colour constancy

responsive to other properties like line orientation, depth and motion

humans show an association between ventral extrastriate subregions and colour processing, but the exact association is still subject to debate

50
Q

cortical blindness

A

blindness due to a cortical issue rather than a problem in the eye or optic nerve

demonstrates that the primary visual cortex is necessary for conscious awareness of the world

51
Q

blindsight

A

condition where people have no conscious experience of seeing, because of extensive damage to striate cortex, but can make rudimentary visual discriminations

likely due to intact tectopulvinar pathway when geniculostriate pathway is damaged

feel like smt is there so you respond to it but do not know why

explanations?:
involves retention of some visual capabilities without the conscious experience of seeing

a small number of LGN pathways bypass striate cortex and go to extrastriate regions instead

maybe a combo of both

52
Q

two main routes that leave the striate cortex

A

ventral - what pathway, identifying objects
dorsal - where pathway, representing their spatial locations

53
Q

audition

A

the perception of sounds

a crucial sensory function essential for unique human capacities such as language

different sensory features such as the pitch, loudness, timing of sounds must be processed in order to: recognize specific auditory events, separate specific sounds from background noises, locate sounds in space

54
Q

auditory pathway

A

pinna
tympanic membrane
ossicles
oval window
cochlea

55
Q

pinna

A

where sound enters

56
Q

ossicles

A

transmit fluid into the cochlea

push in and out on oval window

57
Q

the cochlea

A

an organ in the inner ear that contains hair cells

58
Q

hair cells

A

translate sound vibrations into neural impulses

different sound frequencies stimulate different subsets of hair cells within the cochlea (creates tonotopic map) by knowing which har cells were stimulated, the brain determines which frequencies are present in the sound

stimulated when the membranes more back and forth

movement of cilia in response causes cells ot emit graded potentials

synapses onto spiral ganglion cells - axons make up the auditory nerve

have receptors where ions will flow inside - send signals to ganglion cells

59
Q

organ of corti

A

contains hair cells

in middle of cochlea

fluid filled canal that contains lymph surround the organ of corti

60
Q

basilar membrane

A

tonotopically organized

apex: wide and floppy, low frequency

base: narrow and stiff, high frequency

61
Q

where does auditory info go before reaching the auditory cortex

A

medulla: cochlear nucleus (auditory nerve synapses onto), superior olivary nucleus
midbrain: inferior colliculus
thalamus: medial geniculate nucleus
then info gets sent to primary auditory cortex

62
Q

interaural time difference

A

will reach right ear before it reaches your left

63
Q

interaural intensity difference

A

will be louder when it reaches your right ear

head will block some of the sound

64
Q

where are sounds from above and below computed

A

shaped differently by the structures of the outer ear

cues are analyzed by the auditory system to determine location in the vertical dimension

65
Q

computation of spatial location

A

appears to take place in the brainstem

done in part by using delay lines and cells call coincidence detectors tht take into account the different arrival times of a sound at the left nd right ears

66
Q

core

A

receives input from the medial geniculate nucleus

67
Q

belt

A

receives most of its input from the core

68
Q

parabelt

A

receives input from the belt

69
Q

what is the auditory cortex divided into

A

core, belt, and parabelt

70
Q

tonotopic maps

A

map of sound frequencies

cells that respond best to lower frequencies located rostrally, cells that responds best to higher frequencies located caudally

individual cells have preferred sound frequencies within a particular range will excite the cell

71
Q

sharply tuned curves

A

only fires for very specific Hz

72
Q

broadly tuned curves

A

will fire for a range of Hz

73
Q

planum temporale

A

important for speech perception

auditory pattern recognition

74
Q

posterior regions of auditory cortex

A

information about spatial locations

where

75
Q

anterior regions of auditory cortex

A

information about nonspatial features

what