Block 11 Flashcards
(280 cards)
1
Q
Study of the relationship between the physical stimuli and perceptual responses
A
Psychophysics
2
Q
The minimum quantity of a stimulus that can be detected
A
Threshold
3
Q
Percentage of stimuli detected is plotted as a function of stimuli intensity to produce
A
FOS curve (frequency of seeing) or (psychometric function)
4
Q
Type of observer that’s manifests an unambiguous threshold (never seen below threshold, above threshold is always seen)
A
Ideal observer
5
Q
Type of observer: As the intensity of stimulus in creased, the probability of seeing it increases
A
Real observer
6
Q
Type of observer: no clearly defined intensity below which the stimulus is never seen and above which it is always seen
A
Real observer
7
Q
A diseased visual system in _______ than a healthy one
A
Noises
8
Q
A noiser visual system makes the FOS curve
A
Less steep (more flat)
9
Q
6 mothers to measure the threshold
A
Ascending limits Descending limits Staircase Constant stimuli Adjustment Forced choice
10
Q
How the the method for finding threshold determined
A
By the nature of the experiment or procedure
11
Q
Stimulus is initially not visible, intensity increased until visible, done several times and averaged to determine threshold
A
Method of ascending limits
12
Q
Advantage of method of ascending limits
A
Dark adaptometry
13
Q
Disadvantage of method of ascending limits
A
Observer anticipation (Begin each trial at a different intensity)
14
Q
Reverse method of ascending limits (stimulus clearly visible and decreased until no longer seen)
A
Method of descending limits
15
Q
Advantage of method of descending limits
A
Determination of VA
16
Q
Disadvantage of method of descending limits
A
Observer anticipation
17
Q
Combo of ascending and descending limits
A
Staircase method
18
Q
Advantages of staircase method
A
Quick and reliable
Psychophysical experimentation
Automated visual field testing
19
Q
A “yes/no” procedure where the stimulus is varied randomly and the curve is plotted based on response
- involved blank trials, false positive and false negatives
A
Method of constant stimuli
20
Q
Advantage of method of constant stimuli
A
Maintains observers expectation at same level
21
Q
Diadvantage of method of constant stimuli
A
Time consuming
False pos/neg affect curve and must be adjusted
22
Q
When no stimulus is presented, even though the observer is asked
A
Blank trials
23
Q
Observer reports seeing the stimulus during a blank trial
A
False positive
24
Q
Stimulus is above threshold and the subject reports the stimulus is not seen
A
False negative
25
The subject adjusts the stimulus intensity until it is barely visible/invisible
Method of adjustment
26
Advantage of method of adjustment
Pretty quick
27
Disadvantage of method of adjustment
Repeatability is not as high as other methods
28
What are the 3 observer's criterion involved in forced choice method
1- not all use the 'same criteria'
2- threshold criteria may vary trial to trial for same observer
3- observer Amy use one set of criteria for one type of stimulus and another set for a different stimulus
29
Criterion: do not report seeing a stimulus until absolutely certain (give high threshold)
Strict threshold criterion
30
Criterion: do report seeing a stimulus even though they may have a great deal of uncertainly (give low threshold)
Lax threshold criterion
31
Effects of observer's criteria are minimized by forcing a choice
Forced choice method
32
Example of a 2 forced choice method
Vector vision CSV chart
33
Threshold for a 2AFC (2 alternative forced choice)
75%
34
Threshold is assumed to be the point midway between what
Chance performance and perfect performance
35
How to determine chance performance
The chance that they will get it correct
36
Threshold for 4AFC
62.5%
37
The steeper the curve, the more or less confident?
More
38
Advantages of forced choice method
- lower thresholds
- used effectively to determine the VA and other visual capabilities of infants
- when forced to guess, they do well despite claiming they cannot see the stimulus
39
4 things that influence the determination of threshold
Decision criteria
Attention
Motivation
Internal neural noise
40
What does signal detection theory provide
A useful model to predict the effects of certain factors
41
How are the neural signal produced by the stimulus and neural noise related
Superimposed
42
What is the task of the observer
To differentiate the signal and noise combo FROM background noise
43
Present in the absence of a stimulus
Neural noise
44
Randomly distributed over time and randomly fluctuates over time
Neural noise
45
Stimulus causes a constant level of neural activation to be added to the noise
Noise + signal
46
As the signal becomes larger, what happens to the noise and noise+signal
Get further apart
47
As the signal becomes larger, what happens to detectability
Increases
48
It is easer for observer to determine noise+signal if the signal is: large or small
Larger
49
When there is a large detectability (d), how does a viewer see it
No uncertainty regarding whether it was presented or not
50
How strong is the signal when there is overlap of the N and N+S
Weak stimulus
51
If the stimulus is delivered what the noise is low, what is the resulting level of neural activation
Ambiguous
| - no way to be certain if the stimulus is absent or present
52
If the stimulus is delivered when the noise is high, what is the resulting level of neural activation
Unambiguous
| - neural noise only occurs when stimulus is present
53
When the level of neural activation is above the criterion line, will the subject see the stimulus?
Yes
54
When the level of neural activation is below the criterion line, will the subject see the stimulus?
No
55
The subjects response is determined by what
The level of neural activation
56
Is the subjects response determined by whether the stimulus is presented or not?
No
57
When the stimulus results in a neural activity that exceeds the threshold criterion
Hit
58
When the activity does no exceed the criterion
Miss
59
When the neural activity exceeds the threshold criterion in the absence of a stimuli
False positive
60
When the activity is below the criterion during a blank trial
Correct reject
61
Large number of hits, few misses, but lots of false positive
Lax threshold criterion
62
Few hits, more misses, but few false positives
Strict threshold criterion
63
Curve showing the probability of a hit as a function of the probability of a false positive
ROC curve (receiver operating characteristic)
64
Probability of a high is high, so the probability of a false positive is high
Lax criterion
65
Probability of a hit is low, so the probability of a false positive is low
Strict criterion
66
Weber's law deals with
Contrast
67
Which system is more sensitive when it comes to contrast
Photopic (.015.......scotopic is .14)
68
Discriminate between the combination of stimulus+background and background alone
Weber's law
69
Can be understood using an increment threshold experiment
Weber's law
70
The threshold increment is referred to as
JND (just noticeable difference)
71
As the background intensity increases, what happens to the JND
Increases
72
What happens to the ratio of JND to background intensity as the background intensity increases
The JND increases as well, so the ratio remains constant
73
The ratio of the optotypes to the background luminance (contrast) is the same, no matter the illumination
Lightness constancy
74
Why is the appearance of the E the same under both dim and bright lights
Because of lightness constancy (visual system detects contrast, no absolute luminance)
75
What is the appearance of a stimulus of constant luminance when viewed against backgrounds of various luminance
Brightness depends on background
76
The phenomenon regarding the brightness something appears when viewed against backgrounds of various luminances
Simultaneous contrast
77
Key factor in predicting the brightness of a stimulus (its appearance)
The contrast of the stimulus
78
When no stimulus is presented, even though the observer is asked if they saw
Blank trial
79
during a VF test, pt is reluctant to signal that she sees stimulus even when she may see it. The threshold criteria used by patient is
Strict
80
When determining a clinical threshold, which psychophysical method most minimizes the importance of the patients criterion
Forced choice
81
Common used during automated VF testing
Staircase
82
Which forced choice clinical procedure is expected to result in least steep (flatter)
2AFC
83
Response in which subject reports not seeing a clearly visible, Supra-threshold stimulus is referred to as
False negative
84
If sub threshold and they see
False positive e
85
If sub threshold and they dont see
Correct reject
86
The JCC test for measuring astigmatism is an example of which method
Forced choice
87
If the chance performance of 4AFC is 25%, what is threshold
62.5%
88
When a patient adopts a strict criterion during clinical tests, the result is
Few false positives and few hits
89
Ocular disease is expected to cause the slop of function to
Decrease (get flatter)
90
Weber's law predicts as background intensity increases, contrast threshold
Remains constant
91
When measuring VA with snellen, which method will provide most reliable results
Descending with forced choice
92
As the intensity of background increases, the brightness of a patch inside the background
Decreases
93
According to signal selection theory, a stimulus produces a normal activity that is
Constant
94
Ass the probability of a hit increases, the probability of FP
Increases
95
The method of constant stimuli is designed to keep what constant from trial to trial
Stimulus intensity
| Subject's expectations
96
As stimulus size increased, the detectability
Increases
97
The retinal analyzes data and encodes it into what
A neural signal
98
What cells in the retina produce action potentials
Ganglion and amacrine
99
Small light on center of ganglion receptive field does what to the AP firing
Increases firing
100
Small light on surround of receptive field of ganglion cell does what to AP firing
Decrease firing
101
Large light that covers the entire center of the ganglion cells receptive field does what to AP firing
Increases firing
102
Why is there an increase in AP firing with the light covers the entire center of the ganglion cells receptive field
Due to spatial summation in the field’s center
103
Stimulus that covers the entire receptive field of the ganglion cells will do what to AP
Nothing, acts the same as if there were no stimulus
104
What type of ganglion cells do not respond well to diffuse illumination
Spatially antagonistic GCs
105
What is an example of a strong stimulus for ganglion cells
Sine wave grating
106
The the bright bar of the sine wave grating falls on the center and the dark bars fall on the surround, what does that do to APs
Increase firing
107
Spatial grating does what to a ganglion cell
Vigorously excites
108
When do you reach max firing of AP in a ganglion cell
When the entire center of the receptive field is covered
109
When the stimulus covers the entire receptive field of a GC plus some more area, does this have an affect on the cell’s response
No
110
First cell to respond with an action potential in phototransduction
Amacrine cells
111
What is the order than info is sent in the phototransduction path
```
PR
Horizontal
Bipolar
Amacrine
Ganglion
```
112
Which cells convert light quanta into electrical activity
PRs
113
Resting membrane potential of PR
-50 mV
114
When exposed to light, what happens to PRs
They hyperpolarize and go to -70 mV
115
Which cells produce graded potentials
PR, horizontal, bipolar
116
What does graded potential mean
The more intense the stimulus, the greater the hyperpolarization
117
What does action potential mean
No matter the intensity of the stimulus, the hyperpolarization is the same
118
Steps of phototransduction cascade
1) light converts 11 cis retinal to 11 trans retinal (all-trans retinal)
2) activates transducin
3) activates PDE
4) cGMP to GMP
5) Na+ pores close (no more Na comes in)
6) rod hyperpolarizes
119
Visually inert chain of amino acids
Opsin
120
Rhodopsin consists of 2 portions
Opsin and chromosphere
121
What part of rhodopsin determines the absorption profile of the photopigment
Opsin
122
T or F: rod outer segment sodium channel quantity is limited
True
123
When even a small amount of a rod’s rhodopsin in bleached, what happens to the Na channels
They close
124
Widely dispersed dendritic tree synapses with many PRs
Horizontal cells
125
Type of cell with substantial spatial summation
Horizontal
126
H1 cells have input from which PRs
M and L cones
127
H2 cells have input from which PRs
S cones
128
Type of cell displaying spatial antagonism
Bipolar cells
129
Bipolar cell: Invaginating synapse
On center bipolar
130
Bipolar cell: flat synapse
Off center bipolar
131
Bipolar cell: in the inner sublayer of the IPL
On center bipolar
132
Bipolar cell: in the outer sublayer of the IPL
Off center bipolar
133
Bipolar cell: glutamate is inhibitory
On center bipolar
134
Bipolar cell: glutamate is excitatory
Off center bipolar
135
Bipolar cell: smaller soma, dendritic tree and receptive field
Midget bipolar cell
136
Bipolar cell: center formed by 5-10 M/L cones and center spectral sensitivity is similar to the surround
Diffuse bipolar cells
137
Midget ganglion cells are also called
Parvo cells
138
Diffuse bipolar cells synapse with
Parasol GCs
139
Parasol GCs are also called
Magno cells
140
Are there more parasol GCs in the central 20 degrees or the periphery
Periphery
141
8% of GC, on center formed only by S cones
Small bistratified cells
142
3 places GCs project to
LGN
Superior colliculus
Pulvinar
143
Where to MOST GC projections go to
LGN
144
The superior colliculus controls
Eye movements
145
The pulvinar controls
Visual attention
Motion processing
Visually guided movement
146
Damages choriocapillaris and Bruch’s membrane
ARMD
147
A leading case of blindness
ARMD
148
What type of drugs may help wet ARMD
Angiogenesis blocking drugs
149
Photopigment containing GCS
Melanopsin containing GCs
150
Where to melanopsin GCs project and what are they responsible for
```
Suprachiasmic nucleus (SCN
Circadian rhythm
```
151
Seasonal affective disorder is often treated with
Bright light therapy
152
Extracellular recording techniques may be used to record the activity of which cells
Ganglion and amacrine
| - need an AP to do this
153
LGN: magno cells
2 most ventral layers
154
LGN: parvo cells
4 most dorsal layers
155
LGN: Konio cells
Interlaminar regions
156
Smallest of the LGN cells
Konio cells
157
Where does the LGN primarily project to
Visual cortex
158
Cells sensitive to r/g color contras
Parvo cells
159
Cells making up 70% of the retinogeniculate path
Parvo cells
160
Cells sensitive to rapid movement
Magno cells
161
Cells making up 10% of the retinogeniculate path
Magno cells
162
Which PR primarily feeds into the Magno path
Rods
163
Cells responding to b/y color contrast
Konio cells
164
Which neuron(s) are characterized by color opponency
Parvo and Konio
165
Excited by certain wavelengths and inhibited by others
Color opponenecy
166
Cells showing weak or no color opponency
Magno cells
167
Cells with a sustained response to long duration stimulus
Parvo cells
168
Cells with transient response to long duration stimulus
Magno cells
169
When do you see bursts of activity at the onset and offset, which cells is firing
Magno
170
When you see rapid firing of APs through the entire stimulus, what cell is firing
Parvo
171
Cells with spatial properties similar to retinal midget cells
Parvo
172
Cells with spatial properties similar to retinal parasol cells
Magno
173
Cells with smaller receptive field centers providing higher spatial resolution
Parvo
174
Cells with larger diameter axons, transmitting APs faster
Magno
175
Cells with shorter visual latency
Magno
176
Is there a clear division into distinct parvo and magno in the cortex
No
177
Is there a clear division into distinct parvo and magno in the retinogeniculate path
Yes
178
Lesion of the parvocellular region of LGN
Reduced wavelength discrimination
| Reduced high spatial frequency contrast sensitivity
179
Lesion in magnocellular region of LGN
Reduction of high temporal frequency flicker
| Reduction of low spatial frequency contrast sensitivity
180
Which path is key to color discrimination and visual acuity
Parvo path
181
Pathway encoding fast movement and low spatial frequencies
Magno path
182
Isoluminant gratings isolate which system
Parvo system
183
The bars on isoluminant gratings are only visible due to
Chromatic Contrast
184
Visual field loss indications what kind of cells have died
Ganglion cells
185
Which pathway is more susceptible to damage in glaucoma
Magno
186
Why is the magno path more susceptible to damage in glaucoma
Axons of larger neurons ar damaged earlier than smaller
187
As temporal rate is increased, the healthy patient will note the apparent spatial frequency of the grating doubles
Frequency doubling
188
POAG impairs the perception of
Frequency doubling
189
What type of procedure does the original FDT perimeter threshold testing employ
4-reversal staircase procedure
| - MOBS
190
In the N30-1 screening test, what is the first stimuli presented
One that can be detected by 99% of normal population
191
If the first presented stimulus in the N30-1 screening test is not seen after repeated presentations, what level is then presented
99.5% of the normal population can detect
192
If the target at 99.5% detectibility is not seen in the N30-1 screening test, what is next
Stimulus is presented as max contrast
193
Sensitivity for the N30-1 test
78-92%
194
Specificity of N30-1 screening test
85-100%
195
What makes the N30-1 screening test a useful option for large population screening
The high specificity
196
The first stimulus in the N30-5 screening test
Can be detected by 95% of normal population
197
If the first stimulus in the N30-5 test is not seen after repeated presentations, the next stimulus is
Detected by 98% of population
198
If the 98% detected stimulus is not seen in the N30-5 test, the next stimulus is
Detected by 99%
199
Sensitivity for the N30-5 test
85-95%
200
Specificity of N30-5 test
80-90%
201
The high sensitivity of the N30-5 tests suggests what
It is better for detecting earlier VF loss in glaucoma pts
202
How long to the N30-1 and N30-5 tests take in normal eyes
30 seconds per eye
203
How long does the N30-1 and N30-5 tests take in eyes with VF defects
2 minutes each eye
204
The Humphrey matrix 800 is good for what
Early VF loss detection
205
Data suggests that developmental dyslexics manifest deficits in the processing of
Temporal info
| - MAGNO path
206
Which path encodes motion and low spatial frequencies
Magno path
207
With path encodes r/g chromaticity and high spatial frequencies (VA)
Parvo path
208
Which path processes b/y color info
Konio path
209
Where does the end of the bipolar cell with flat/invaginating synapses occur
OPL
210
Isoluminant gratings are thought to be detect by
Parvo cells
211
Located in the 2 ventral layers of the LGN
Magno cells
212
Have transient neural response
Magno cels
213
Have strong color opponency
Parvo
| Konio
214
Synapse in layer 4Calpha of the cortex
Magno
215
Synapse in layer 4Cbeta of the cortex
Parvo
216
Sustained neural response
Parvo
217
Parvo cells continue about what percentage of ganglion cells
70%
218
Magno cells constitute about what percentage of ganglion cells
10%
219
An on center magno neuron is least responsive to
Isoluminant grating
220
A lesion on in the parvocelluar region of the LGN is expected to result in a reduction in
Visual acuity
Wavelength discrimination
Low temporal frequency
221
A lesion in the magnocellualr region of the LGN is expected to result in a redction in
High frequency temporal resolution
222
In frequency doubling, what aspect of the stimulus appears to double as the temporal frequency increase
Spatial frequency
223
Neurons in the 4 most dorsal layers of the primate LGN manifest what property
Color opponency
224
Max sensitivity to low spatial frequencies
Magno
225
4 most dorsal layers of LGN
Parvo
226
2 most ventral alyers of LGN
Magno
227
Thicker/larger diameter axons
Magno
228
Action potentials faster or shower in parvo
Slower
229
What are the smallest cells
Konio
230
Which cells are noncolor opponent
Magno
231
Cytochrome oxidase blobs are located in
Striate cortex
232
The more superficial layers of striate cortex projec to
Higher cortical area
233
Double color opponent neurons are located in the
Blobs
234
Info from the 2 eyes is first combined in cells within
Striate cortex
235
The receptive fields of which cells cannot be mapped out with small spots of light
Complex
236
The receptive fields of which cells can be mapped out with small spots of light
Simple
237
Spatially nonlinear magno cells are thought to provide input to
Complex cortical cells
238
A hypercolum contains a complete set of
Ocular dominance columns
| Orientation columns
239
Simple cell receptive field properties
Distant on and off region
Orientation selectivity
Position selectivity
240
Cells that mediate stereopsis are found in
Cortex
241
Neuron expected to be most responsive to an isoluminant grating
Double color opponent cortical cell
242
May be demonstrated using forced choice methodology
Blindsight
243
The cortex contains about how many areas predominantly devoted to analyzing visual info
20
244
Striate cortex projects to
Extra striate cortex
LGN
Pulvinar
245
Striate cortex receives input from
Extra striate cortex
| LGN
246
Optical imaging of intrinsic signals in striate cortex reveals that orientation sensitivity is arranged in formations that appear as
Pinwheels
247
Which lobe is the striate cortex in
Occipital lobe
248
Other names fro the striate cortex
Primary visual cortex
Visual area 1
V1
Brodmann area 17
249
A representation of the entire visual field
Striate cortex
250
Comprises only .01% of retinal area
Fovea
251
Represented in at least 8% of striate cortex
Fovea
252
The temporal path
Ventral stream
253
The what system
Ventral processing stream
254
Relieves input form parvo path
Ventral processing
255
Parietal path
Dorsal processing stream
256
The where system
Dorsal processing stream
257
Recieves input from magno path
Dorsal processing
258
Are the 2 cortical processing streams independent
No
259
Projections to lower visual centers originate from what layers of the striate cortex
Deeper layers (layer 6)
260
The projections to the extra striate cortex originate more from what layers of the striate cortex
Superficial layers (layers 2/3)
261
Cells most sensitive to a bar or edge of a specific orientation
Simple cells
262
Receptive fields are divided into antagonistic excitatory and inhibitory regions
Simple cells
263
Type of processing used by simple cells
Serial processing
264
Cells responding best to an elongated stimulus of a specific orientation
Complex cells
265
With which cells are certain cortical neurons sensitive to stimulus length
Complex cells
266
With which cells must the stimulus be a specific width and orientation
Simple cells
267
Which cells respond to diffuse light
PRs
268
Which cells respond to a spot of light of a specific diameter
Ganglion cells
269
What cells respond to a bar of light moving in the proper direction
Complex cells
270
Both pathways (parvo and magno) have what kind of processing
Hierarchical
271
Which neurons respond well to sine wave grating and are selective for a particular spatial frequency
Cortical neurons
272
Line or surface content all points in space whose images fall on corresponding points of each eye retina
Horopter
273
Stimulation of a neuron through the dominant eye causes
A stronger response
274
A complete set of ocular dominance columns(both eyes) and orientation columns(all orientations)
Hyper column
275
The development of standard cortical architecture requires
Normal visual input early in life
276
Optimally responsive to stimuli that manifest color contrast
Striate blobs
277
Superficial region of striate cortex between bobs that recieves substantial parvo input
Interblob region
278
Pathway that bypasses blobs
Magno
279
Which path feeds exclusively into one of the cortical processing streams
Neither parvo nor magno
280
Why are receptive fields of striate cortical neurons more complicated
Due to hierarchical processing
