Lecture 3: Basic elements of neurophysiology and psychophysics 2

Question 1

What can be used to study sensation and perception = name

Answer 1

Physiological
Computational (psychophysics)

Question 2

Describe physiological method

Answer 2

Nothing about perception

Question 3

Describe computational method

Answer 3

Predicts subjective perception
Nothing about computational

Question 4

Describe 3 steps of sensation and perception

Answer 4

Physical stimulus —> 1. TRANSDUCTION —. 2. TRANSMISSION/MODULATION —> 3. PERCEPTION/MODULATION

Question 5

Define transduction

Answer 5

Physical stimulus interacts with a specific receptor - with neuron system, located on peripheral sensory neuron and causes the neuron to fire = stimulus transduced into electrical signal

Question 6

What is at the surface of dendirtes

Answer 6

Complex proteins called trasnducers

Question 7

Name the 2 main types of transducers

Answer 7

Cmr1 = for cold temp
Vr1 and Vrl-1 = for warm temp

Question 8

How does temp affect transducers

Answer 8

Chemical reaction = changes membrane polarity
Na enters nerve cell = changes polarity

Question 9

Describe cold perception transducers

Answer 9

Reduce polarity of membrane of neuron - if many events occur = fire ap
In mint = menthol, same impact on trasnducers

Question 10

Describe hot perception trasnducers

Answer 10

Polarity reduces = activates same neural pathway
If capsaicin - in peppers - cannot damage neurons tho =illusion of pain - pain without injury

Question 11

What is an action potential

Answer 11

Rapid temporary electrical signal
Travels along membrane of a neuron or muscle cell
Occurs when cells memrbane potential rapidly depolariezes and then repolarizes = allows cell to transmit info or tigger response

Question 12

What is electrode

Answer 12

Measures = put on/near axon

Question 13

Describe action potential firing generally

Answer 13

Physical stimulus = transduced or encoded
Causes us to perceive it eventually

Question 14

Describe action potential firing NO STIMULUS

Answer 14

Neuron fires at baseline
Residual activity = always some activity, baseline spontaneous firing

Question 15

Describe action potential firing WEAK STIMULUS

Answer 15

Induces ap at low firing rate
Encode intensity of physical stimulus = by firing rate/frequency of aps

Question 16

Describe action potential firing STRONG STIMULUS

Answer 16

Induces action potentials at high firing rate
Increase frequency firing rate = activity increases with intensity

Question 17

DESCRIBE cranial nerves - transmission

Answer 17

Sensory organs mostly in head
Neural signal enters cns (brain + spinal cord) = sensory info enters brain through cranial nerves mostly

Question 18

Describe somatic nerves - transmission

Answer 18

Sensory signals enter spinal cord by peripheral nerves = enter spinal cord between each vertebrae
Somatosensation = perception of body = different

Question 19

Describe synapse - transmission

Answer 19

Peripheral neuron will transmit to another neuron in cns through synapse
Presyn terminal close to dendrites postsyn neuron = exchange info
Through nts released in synaptic cleft
Binds receptors then postsyn = inhibited or excited = signal trasnmitted

Question 20

Describe thalamus

Answer 20

First relay in brain = for most senses = vision, optic nerve
Structure in middle fo brain = small, organized into diff nuclei = some sensory, motor, involved in cognitive stuff
Exchange info with cortex (dispatcher)

Question 21

Describe modulation

Answer 21

Transmission = opportunity for modulation
Brain has capacity to modulate = increase or decrease signal it’s receiving from peripheral sensory neuron
Sites of modulation = thalamus

Question 22

Describe modulation Ex

Answer 22

Thalamus blocks sensory info to brain when sleep = almost all info blocked = prevents info from reaching cortex

Question 23

Describe perception

Answer 23

Sensory signals reach sensory corgi legs = first place sensory info relayed at level of cortex
Not suffiencient - need other aspects too
Begin to see conscious perception of environment

Question 24

Describe perception modulation

Answer 24

Influenced by expectations = placebo effect, phantom sensations, perceive things not there

Question 25

Describe subliminal perception

Answer 25

Stimulus processes at level of cortex but individual unaware Like blind side - happens at level fo thalamus = think they cannot see but accuracy when locating things

Question 26

When Stanley smith stevens

Answer 26

1906-1973

Question 27

What stevens question

Answer 27

Compare 2 physical stimuli In proportion how much more/less intense are 2 stimuli of diff inetnsites perceived Like shock 2x at diff intensities and ask how much larger/smaller

Question 28

Stevens formula

Answer 28

Psy (I) = kI^a

Question 29

What does psy stand for- stevens formula

Answer 29

Subjective percept

Question 30

What does I stand for- stevens formula

Answer 30

Stimulus intensity

Question 31

What does a stand for- stevens formula

Answer 31

Controls curvature of fucntion a > 1= exponential, a=1 = linear, a<1 =log

Question 32

What does K stand for- stevens formula

Answer 32

Corrects for scaling of measurement units used for I

Question 33

DESCRIbe stevens formula - graph

Answer 33

X = stimulus intensity Y= magnitude estimate Visual length = 1 = linear Loudness = a=0.670, lower ranges matter more bc where we talk, logo shape = not as important to pericve v loud bc its just too loud Pain = steeper, exponential, can distinguish better when close to causing physical harm, speed of growth increases wirh stimulus intensity, most sensitive close to modality that causes injury

Question 34

What are absolute magnitude ratings

Answer 34

Visual analog scale 0-100 How intense is a percept in relation to 2 absolute boundaries Compare stimuli = reliable, but hard to study individual variability = depends on imagination

Question 35

What is problem with magnitude rating

Answer 35

Hwo can we compare = Is my 10/100 equal to your 10/100

Question 36

What is solution for magnitude ratings issue

Answer 36

Cross modality matching Rely on past experiences to rate thing, so should rescale Ex = super tasters more sensitive bc more taste buds, rate coke high sweetness on cross modality matching scale but not on regular magnitude rating scale

Question 37

Describe why generalized labelled magnitude scale better

Answer 37

Allows us to know what in someone else’s mind = better idea of sensitivity using scale with sensory modalities Use more than one sensory modalities on scale Works by prothetic sensations

Question 38

What are prothetic sensations

Answer 38

Sensory experiences that vary in intensity or magnitude Like loudness, brightness, weight Measured on a continuous scale Additive in nature Can convert audition to visual, put diff numbers on them and study scientifically

Question 39

What are metathetic sensations

Answer 39

Sensory expiences that vary in quality or kind Like changes in pitch, colour or taste Involve categorical or qualitative changes rather than variations in intensity More qualitative

Question 40

Describe difference threshold

Answer 40

Smallest detectable difference between 2 stimuli that a person can perceive Aka JND

Question 41

Describe detection threshold

Answer 41

Minimum intensity of a stimulus required for person to perceive its presence

Question 42

Is there one specific cut off value that perfectly serapes stimuli for whom teh difference is always perceived vs never perceived

Answer 42

NOOOOO Because of variability in relationship between stimulus intensity and sensory perception = no one cut off value

Question 43

The threshold is what

Answer 43

PROBABILISTIC= define as difference in stimulus intensity for which a difference is expected to be perceived 50% of the time Threshold often assessed by fitting a logistic regression curve to data from thresholding procedure

Question 44

Describe threshold graph

Answer 44

S shaped graph Yes or no difference perceived ^ (if difference small = usually no perceived, if difference high = usually yes perceived) Magnitude of differnce betwene standard and test stimuli > Identity where there is 50% chance periceiving differnce NO CLEAR VALUE OF X THO

Question 45

What is Jnd

Answer 45

Difference threshold

Question 46

Describe method fo constant stimuli

Answer 46

Sample range of physical stimulus intensities - randomly Ones at diff levels and ask if they feel it More accurate Fits logistic regression Extremes of stimulus intensity uninformative

Question 47

Describe method of limits for thresholding

Answer 47

Start High then go low Then start low and go high Until reach reversal in response Faster, less accurate bc less data points

Question 48

Describe staircase method for thresholding

Answer 48

Start high then get reversal and go back and forth step by step V efficient, oscillates around threshold = narrows down easily

Question 49

Describe method of adjustment for thresholding

Answer 49

Less accurate V fast Use dial = participant controls intensity, and ask them to report when perceive it = where threshold is

Question 50

Where was primary auditory cortex

Answer 50

Temporal lobe

Question 51

Where is primary visual cortex

Answer 51

Occipital lobe

Question 52

Where is primary somatosensory cortex

Answer 52

Parietal lobe

Question 53

Is pain prothetic or metathetic

Answer 53

Pain quality = metathetic Pain intensity = prothetic PAIN IS SUPER COMPLEX