Sensation & Perception Flashcards
(111 cards)
1
Q
Sensation def.
A
Can be considered transduction - the conversion of physical, electromagnetic, auditory, and other information to electrical signals in the nervous system
performed by receptors in the PNS
2
Q
Perception def.
A
Processing of sensory information to make sense of its significance
3
Q
Sensory receptors
A
Neurons that respond to stimuli and trigger electrical signals
-can encode multiple aspects of a stimulus
4
Q
Ganglia
A
collections of neuron cell bodies found outside the CNS
-used to transmit information from the receptors to the CNS
5
Q
Photoreceptors
A
respond to electromagnetic waves in the visible light spectrum
6
Q
hair cells
A
respond to movement of fluid in the inner ear structures
-hearing, rotational and linear acceleration
7
Q
nociceptors
A
respond to painful or noxious stimuli (somatosensation)
8
Q
thermoreceptors
A
respond to changes in temperature
9
Q
osmoreceptors
A
respond to the osmolarity of the blood
10
Q
olfactory receptors
A
respond to volatile compounds
11
Q
taste receptors
A
respond to dissolved compounds
12
Q
Threshold
A
minimum amount of a stimulus required to render a change in perception
13
Q
Absolute threshold
A
minimum stimulus energy needed to activate a sensory system
- threshold in sensation not perception
- how bright/loud/intense a stimulus must be before we sense it
14
Q
Threshold of conscious perception
A
sensory signals can reach the CNS without perception occurring
-stimulus is to subtle or brief to be attended to
15
Q
Difference threshold
A
also called the just-noticeable threshold
minimum difference in magnitude between two stimuli before one can perceive this difference
16
Q
Weber’s law
A
Constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus
= change in stimulus / original stimulus magnitude
17
Q
signal detection theory
A
How the perception of stimuli can be affected by nonsensory factors such as memory, motives and expectation
18
Q
Response bias
A
tendency of subjects to respond systematically to a stimulus in a certain way due to nonsensory factors
-can be determined by the proportion of misses or false alarms in an experiment
19
Q
Basic signal detection experiment components
A
catch trial: signal is presented
noise trial: signal is not presented
hits: correct perception of signal
misses: fails to perceive given signal
false alarms: perceives signal when none was given
correct negatives: correct identification of no signal
20
Q
The eye detects light in the form of _____
A
photons
21
Q
Sclera
A
“white” of the eye
- thick structural layer
- does not cover the front most part of the eye
22
Q
Two sets of vessels supplying the eye
A
- choroidal vessels (b/w retina and sclera)
2. retinal vessels
23
Q
Retina - form & function
A
innermost layer of the eye
- consists of neural elements and blood vessels
- develops as an outgrowth of brain tissue (part of CNS)
function: convert incoming photons of light into electrical signals
24
Q
Cornea
A
clear, domelike window in the front of the eye
-gathers and focuses incoming light
25
Anterior chamber
Part that is in front of the iris
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Posterior chamber
between the iris and the lens
| -where aqueous humor is made by the ciliary body
27
Iris
Coloured part of the eye
- dilator pupillae: opens the pupil under sympathetic stimulation
- constrictor pupillae : constricts the pupil under parasympathetic stimulation
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choroid
middle layer of the eye
| -continuous with the iris as well as the ciliary body
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Ciliary body
produces aqueous humor that bathes the front part of the eye
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Canal of Schlemm
drains the aqueous humor
31
Lens
Helps control the refraction of incoming light
- located behind the iris
- shape is changed by contraction of the ciliary muscle which is under parasympathetic control
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Accomodation
Process in which the ciliary muscle contracts, pulling on the suspensory ligaments which changes the shape of the lens
33
Vitreous
transparent gel that supports the retina
34
Duplexity/Duplicity theory of vision
retina contains two different kinds of photoreceptors (rods and cones)
35
Rods
- Work best in reduced lighting
- Only allow for sensation of light or dark as they only contain one pigment: rhodopsin
- low sensitivity to detail
*~120 million rods in the retina
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Cones
- Work best in bright light (different cones absorb different wavelengths of light: short, medium, long)
- Used for colour vision
- High sensitivity to detail
37
Macula
central section of the retina with a high concentration of cones
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Fovea
centermost point of the macula, contains ONLY cones
| -visual acuity is best at the fovea
39
Blind spot
where the optic nerve leaves the eye
| -no photoreceptors present
40
Bipolar cells
connect with rods and cones
synapse with ganglion cells
41
Ganglion cells
connect with bipolar cells
group together to form the optic nerve
* each one represents the combined activity of many rods and cones
- this results in a loss of detail as info from photoreceptors is combined
42
Amacrine and Horizontal cells
Receive input from multiple retinal cells in the same area before the info is passed to ganglion cells
- accentuate slight differences between visual information in each bipolar cell
- increase perception of contrasts
43
Visual pathways
both the physical connections between the eyes and the brain AND the flow of visual information along these connections
44
Optic chiasm
Where the fibers from the nasal half of each retina cross paths
- fibres carry information form the temporal visual field from each eye
* temporal fibres (carrying the information from the nasal visual field) do not cross the chiasma
==> because of this, all information from the left visual field of each eye projects to the right side of the brain and visa versa
45
Optic tracts
reorganized pathways leaving the optic chiasm
-travel to:
the lateral geniculate nucleus
Visual cortex (occipital lobe) via radiation in the temporal and parietal lobes
46
Lateral geniculate nucleus (LGN)
Located in the thalamus
47
Parallel processing
ability to simultaneously analyze and combine information regarding colour, shape, and motion
-then compare images to memories to determined what is being viewed
48
Parvocellular cells
Detect shape in the visual pathway
- have very high colour spatial resolution
- permit fine detail when an object is stationary
- poor temporal resolution = not for moving objects
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Magnocellular cells
Detect motion in the visual pathway
- high temporal resolution
- low spatial resolution
* provide a blurry but moving image of the object
50
Vestibular Sense
rotational and linear acceleration
51
Pinna/Auricle
cartilaginous outer part of the ear
- first part of the ear that the sound passes through
- function is to channel sounds waves into the external auditory canal
52
External auditory canal
Canal of the outer ear
| -directs sound waves to the tympanic membrane
53
Tympanic membrane
Vibrates in phase with the incoming sound waves
- frequency of the sound waves determines the rate at which the tympanic membrane vibrates (high frequency = high vibration)
- Louder sounds have greater intensity and therefor greater amplitude of vibration
*Divides the middle ear and the outer ear
54
Ossicles
three smallest bones in the body
- found in the middle ear
- malleus, incus, staples
55
Order of ossicle action
1. Malleus acts on the => 2. Incus acts on the => 3. Stapes => presses on the oval window of the cochlea
56
Eustachian tube
Connects the middle ear to the nasal cavity
| -helps equalize pressure between the middle ear and the environment
57
Inner ear
Located in a bony labyrinth
- contains the cochlea, vestibule and the semicircular canals
- structures are continuous with each other and filled by the membranous labyrinth which in turn is filled with a K+ rich fluid called endolymph
58
Endolymph
Potassium rich fluid that fills the membranous labyrinth
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Cochlea: structure & function
Spiral shaped organ divided into 3 parts called scalae
- middle scalae houses the organ of Corti (resting on the basilar membrane)
- tectorial membrane (immobile) rests on top of the organ of Corti
60
Organ of Corti
comprised of thousands of hair cells that are bathed in endolymph
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Perilymph
Transmits vibrations from the outside world and cushions the inner ear structures
-fills the other 2 scalae of the cochlea
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Round window
Membrane covered role in the cochlea (lower down than the oval window) that allows the perilymph in the outer scalae to move
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Basilar membrane movements
Sound entering the cochlea via the oval window causes vibrations in the perilymph which are transmitted to the basilar membrane
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Which nerve carries stimulus to the CNS?
Auditory (vesibulocochlerar) nerve
65
Vestibule
Portion of the bony labyrinth that contains the utricle and the saccule
- sensitive to linear acceleration
- used as part of balancing apparatus
- determining orientation in 3D space
66
Hair cells of the utricle and saccule
Covered with otoliths
- as the body accelerates the otoliths resist the motion, causing the hair to bend
- the hair cells are then stimulated and send a message to the brain
67
Semicircular Canals
3 semicircular canals are sensitive to rotational acceleration
- arranged perpendicular to each other
- each end in a swelling called the ampula where the hair cells are located
*when the head rotates, endolymph resists this motion and cause the hairs to bend, sending signals to the brain
68
Auditory pathways (order)
1. Most signals pass through the vestibularcochlear nerve to the brainstem
2. Then it ascends to the medial geniculate nucleus of the thalamus
3. Projects to the auditory cortex in the temporal lobe for sound processing
* * some info also sent to superior olive (localization) and the inferior colliculus (startle response)
69
Vestibulo-ocular reflex
Keeping the eyes fixed on a point which the head is turning
- startle response
- involves the inferior colliculus
70
Hair cell structure
Have long tufts of stereocilia on surface
71
Hair cell function
1. Vibrations on the basilar membrane causes movement of endolymph and stereocilia to sway
2. Swaying causes the opening of ion channels
3. A receptor potential is created
72
Hair cells + tectorial membrane
Hair cells directly connected to the tectorial membrane are involved in amplifying incoming sounds
73
Tonotopical organization of cochlea
Basilar membrane thickness changes throughout the cochlea
- closest to oval window = highest frequency pitches
- furthest from oval window = lowest frequency pitches
74
Only 1 of the senses that does not pass via the thalamus
Smell
75
Smell is considered a ____ sense
Chemical sense
| -responds to volatile or aerosolized chemicals
76
Olfactory chemoreceptors (nerves)
Located in the olfactory epithelium in the upper part of the nasal cavity
- highly varied
- chemicals must bind to specific receptors
77
Pheromones
Secreted by one person or animals and bind to the chemoreceptors of another, urging them to behave in a certain way
78
Olfactory pathway
1. Odor molecules are inhaled into the nasal passages
2. contact the olfactory nerves
3. olfactory receptors are activated and they send signals to the olfactory bulb
4. Signals are then relayed via the olfactory tract to higher regions of the brain (ie. limbic system)
79
5 basic tastes
Sweet, sour, bitter, salty, and umami (savoury)
80
Flavour
Complex interplay between smell and taste
| -can be affected by non-chemical stimuli
81
Taste chemoreceptors
sensitive to dissolved chemicals
82
Taste buds
groups of cells that are receptors for taste
83
Papillae
small bumps on the tongue which contain the taste buds
84
Taste pathway
1. Info travels from taste buds to the brainstem
2. Ascends to the taste centre in the thalamus
3. Travels from the thalamus to higher order brain regions
85
4 modalities of Somatosensation
1. Pressure
2. Vibration
3. Pain
4. Temperature
86
Brown-Séquard syndrome
If half the spinal cord is severed the patient loses pain and temperature sensation on the opposite side of the lesion and pressure/vibration sensation on the same side
*pain + temp use a different pathway then pressure +vibration
87
Pacinian corpuscules
respond to deep pressure and vibration
88
Meissner corpuscules
respond to light touch
89
Merkle cells (discs)
respond to deep pressure and texture
90
Ruffini endings
respond to stretch
91
Free nerve endings
respond to pain and temperature
92
Somatosensory signal destination
Somatosensory cortex in parietal lobe
93
Two point thresholds
minimum distance necessary between two points of stimulation on the skin such that the points will be felt as distinct
94
Physiological zero
Normal temperature of the skin
| -objects feel cold if they are below and hot if they are above
95
Nociceptors
Involved in pain perception (most common receptor)
96
Gate theory of Pain
Special gating mechanism present that can turn pain signals on and off
Spinal cord can preferentially forward signals from other touch modalities, therefore reducing the pain sensation
97
Kinesthetic sense
Also known and proprioception
| = ability to tell where one's body is in space
98
Location of proprioception receptors
Mainly muscles and joints
99
Bottom up processing
object recognition by parallel processing and feature detection
-combining stimuli into a cohesive image before determining what the object is
*also called data-drive processing*
100
Top down processing
Driven by memories and expectation which allow the brain to recognize the whole object, then to recognize its components based on these expectations
-allow for quicker recognition
101
Perceptual organization
Ability to use both top down and bottom up processing in tandem with other sensory clues about an object to create a complete picture
102
Depth perception
monocular clues: relative size of the object, partial obscuring, convergence of parallel lines at a distance, position of object in visual field, and lights/shadows
binocular clues: slight differences in images projected on the 2 retinas and the angle required between the eyes to bring an object into focus
103
Form of an object
determined via parallel processing and feature detection
104
Constancy
idea that we can perceive certain characteristics of objects to remain the same, despite changes in the environment
105
Gestalt principles
ways for the brain to infer missing parts of a picture when it is incomplete
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Law of proximity
elements close together tend to be perceived as a unit
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Law of similarity
objects that are similar tend to be grouped together
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Law of good continuation
elements that appear to follow the same pathway tend to be grouped together
-perceive continuous patterns over abrupt changes
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Subjective contours
perceive contours and therefore shapes that are not actually present
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Law of closure
A space that is surrounded by a contour it tends to perceived as a complete figure
-certain figures tend to be perceived as more complete than they actually are
111
Law of prägnanz
perceptual organization will always be as regular, simple, and symmetric as possible
-governs the other gestalt principles
