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MCAT Behavioural Sciences > Sensation & Perception > Flashcards

Sensation & Perception Flashcards

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MCAT flashcards
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

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2
Q

Perception def.

A

Processing of sensory information to make sense of its significance

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3
Q

Sensory receptors

A

Neurons that respond to stimuli and trigger electrical signals
-can encode multiple aspects of a stimulus

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4
Q

Ganglia

A

collections of neuron cell bodies found outside the CNS

-used to transmit information from the receptors to the CNS

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5
Q

Photoreceptors

A

respond to electromagnetic waves in the visible light spectrum

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6
Q

hair cells

A

respond to movement of fluid in the inner ear structures

-hearing, rotational and linear acceleration

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7
Q

nociceptors

A

respond to painful or noxious stimuli (somatosensation)

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8
Q

thermoreceptors

A

respond to changes in temperature

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9
Q

osmoreceptors

A

respond to the osmolarity of the blood

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10
Q

olfactory receptors

A

respond to volatile compounds

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11
Q

taste receptors

A

respond to dissolved compounds

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12
Q

Threshold

A

minimum amount of a stimulus required to render a change in perception

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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
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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

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15
Q

Difference threshold

A

also called the just-noticeable threshold

minimum difference in magnitude between two stimuli before one can perceive this difference

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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

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17
Q

signal detection theory

A

How the perception of stimuli can be affected by nonsensory factors such as memory, motives and expectation

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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

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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

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20
Q

The eye detects light in the form of _____

A

photons

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21
Q

Sclera

A

“white” of the eye

  • thick structural layer
  • does not cover the front most part of the eye
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22
Q

Two sets of vessels supplying the eye

A
  1. choroidal vessels (b/w retina and sclera)

2. retinal vessels

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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

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24
Q

Cornea

A

clear, domelike window in the front of the eye

-gathers and focuses incoming light

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25
Q

Anterior chamber

A

Part that is in front of the iris

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26
Q

Posterior chamber

A

between the iris and the lens

-where aqueous humor is made by the ciliary body

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27
Q

Iris

A

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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28
Q

choroid

A

middle layer of the eye

-continuous with the iris as well as the ciliary body

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29
Q

Ciliary body

A

produces aqueous humor that bathes the front part of the eye

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30
Q

Canal of Schlemm

A

drains the aqueous humor

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31
Q

Lens

A

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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32
Q

Accomodation

A

Process in which the ciliary muscle contracts, pulling on the suspensory ligaments which changes the shape of the lens

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33
Q

Vitreous

A

transparent gel that supports the retina

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34
Q

Duplexity/Duplicity theory of vision

A

retina contains two different kinds of photoreceptors (rods and cones)

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35
Q

Rods

A
  • 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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36
Q

Cones

A
  • Work best in bright light (different cones absorb different wavelengths of light: short, medium, long)
  • Used for colour vision
  • High sensitivity to detail
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37
Q

Macula

A

central section of the retina with a high concentration of cones

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38
Q

Fovea

A

centermost point of the macula, contains ONLY cones

-visual acuity is best at the fovea

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39
Q

Blind spot

A

where the optic nerve leaves the eye

-no photoreceptors present

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40
Q

Bipolar cells

A

connect with rods and cones

synapse with ganglion cells

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41
Q

Ganglion cells

A

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
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42
Q

Amacrine and Horizontal cells

A

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
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43
Q

Visual pathways

A

both the physical connections between the eyes and the brain AND the flow of visual information along these connections

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44
Q

Optic chiasm

A

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

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45
Q

Optic tracts

A

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
Q

Lateral geniculate nucleus (LGN)

A

Located in the thalamus

47
Q

Parallel processing

A

ability to simultaneously analyze and combine information regarding colour, shape, and motion
-then compare images to memories to determined what is being viewed

48
Q

Parvocellular cells

A

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
49
Q

Magnocellular cells

A

Detect motion in the visual pathway

  • high temporal resolution
  • low spatial resolution
  • provide a blurry but moving image of the object
50
Q

Vestibular Sense

A

rotational and linear acceleration

51
Q

Pinna/Auricle

A

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
Q

External auditory canal

A

Canal of the outer ear

-directs sound waves to the tympanic membrane

53
Q

Tympanic membrane

A

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
Q

Ossicles

A

three smallest bones in the body

  • found in the middle ear
  • malleus, incus, staples
55
Q

Order of ossicle action

A
  1. Malleus acts on the => 2. Incus acts on the => 3. Stapes => presses on the oval window of the cochlea
56
Q

Eustachian tube

A

Connects the middle ear to the nasal cavity

-helps equalize pressure between the middle ear and the environment

57
Q

Inner ear

A

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
Q

Endolymph

A

Potassium rich fluid that fills the membranous labyrinth

59
Q

Cochlea: structure & function

A

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
Q

Organ of Corti

A

comprised of thousands of hair cells that are bathed in endolymph

61
Q

Perilymph

A

Transmits vibrations from the outside world and cushions the inner ear structures
-fills the other 2 scalae of the cochlea

62
Q

Round window

A

Membrane covered role in the cochlea (lower down than the oval window) that allows the perilymph in the outer scalae to move

63
Q

Basilar membrane movements

A

Sound entering the cochlea via the oval window causes vibrations in the perilymph which are transmitted to the basilar membrane

64
Q

Which nerve carries stimulus to the CNS?

A

Auditory (vesibulocochlerar) nerve

65
Q

Vestibule

A

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
Q

Hair cells of the utricle and saccule

A

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
Q

Semicircular Canals

A

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
Q

Auditory pathways (order)

A
  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
Q

Vestibulo-ocular reflex

A

Keeping the eyes fixed on a point which the head is turning

  • startle response
  • involves the inferior colliculus
70
Q

Hair cell structure

A

Have long tufts of stereocilia on surface

71
Q

Hair cell function

A
  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
Q

Hair cells + tectorial membrane

A

Hair cells directly connected to the tectorial membrane are involved in amplifying incoming sounds

73
Q

Tonotopical organization of cochlea

A

Basilar membrane thickness changes throughout the cochlea

  • closest to oval window = highest frequency pitches
  • furthest from oval window = lowest frequency pitches
74
Q

Only 1 of the senses that does not pass via the thalamus

A

Smell

75
Q

Smell is considered a ____ sense

A

Chemical sense

-responds to volatile or aerosolized chemicals

76
Q

Olfactory chemoreceptors (nerves)

A

Located in the olfactory epithelium in the upper part of the nasal cavity

  • highly varied
  • chemicals must bind to specific receptors
77
Q

Pheromones

A

Secreted by one person or animals and bind to the chemoreceptors of another, urging them to behave in a certain way

78
Q

Olfactory pathway

A
  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
Q

5 basic tastes

A

Sweet, sour, bitter, salty, and umami (savoury)

80
Q

Flavour

A

Complex interplay between smell and taste

-can be affected by non-chemical stimuli

81
Q

Taste chemoreceptors

A

sensitive to dissolved chemicals

82
Q

Taste buds

A

groups of cells that are receptors for taste

83
Q

Papillae

A

small bumps on the tongue which contain the taste buds

84
Q

Taste pathway

A
  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
Q

4 modalities of Somatosensation

A
  1. Pressure
  2. Vibration
  3. Pain
  4. Temperature
86
Q

Brown-Séquard syndrome

A

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
Q

Pacinian corpuscules

A

respond to deep pressure and vibration

88
Q

Meissner corpuscules

A

respond to light touch

89
Q

Merkle cells (discs)

A

respond to deep pressure and texture

90
Q

Ruffini endings

A

respond to stretch

91
Q

Free nerve endings

A

respond to pain and temperature

92
Q

Somatosensory signal destination

A

Somatosensory cortex in parietal lobe

93
Q

Two point thresholds

A

minimum distance necessary between two points of stimulation on the skin such that the points will be felt as distinct

94
Q

Physiological zero

A

Normal temperature of the skin

-objects feel cold if they are below and hot if they are above

95
Q

Nociceptors

A

Involved in pain perception (most common receptor)

96
Q

Gate theory of Pain

A

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
Q

Kinesthetic sense

A

Also known and proprioception

= ability to tell where one’s body is in space

98
Q

Location of proprioception receptors

A

Mainly muscles and joints

99
Q

Bottom up processing

A

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
Q

Top down processing

A

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
Q

Perceptual organization

A

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
Q

Depth perception

A

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
Q

Form of an object

A

determined via parallel processing and feature detection

104
Q

Constancy

A

idea that we can perceive certain characteristics of objects to remain the same, despite changes in the environment

105
Q

Gestalt principles

A

ways for the brain to infer missing parts of a picture when it is incomplete

106
Q

Law of proximity

A

elements close together tend to be perceived as a unit

107
Q

Law of similarity

A

objects that are similar tend to be grouped together

108
Q

Law of good continuation

A

elements that appear to follow the same pathway tend to be grouped together
-perceive continuous patterns over abrupt changes

109
Q

Subjective contours

A

perceive contours and therefore shapes that are not actually present

110
Q

Law of closure

A

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
Q

Law of prägnanz

A

perceptual organization will always be as regular, simple, and symmetric as possible
-governs the other gestalt principles

MCAT Behavioural Sciences (12 decks)

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