Exam 1 Flashcards
(97 cards)
1
Q
What is the definition of sensation?
A
initial steps in converting physical stimulation to electrochemical signals
2
Q
What is the definition of perception?
A
later steps in which representations are formed to guide other behavior
3
Q
What is the difference between distal and proximal stimulus?
A
distal is physical objects/events in the environment. proximal is physical phenomenon evoked by distal stimulus on sensory receptors.
4
Q
What is the difference between transduction and transmission?
A
transduction occurs when environmental energy changes to nerve impulses. transmission occurs when signals from the receptors travel to the brain
5
Q
What is an action potential?
A
rapid increase in positive charge in a nerve fiber that travels down the fiber
6
Q
Which part of the neuron sends out the action potential?
A
axon (nerve fiber)
7
Q
A synapse is a specialized junction between two neurons. What is the difference between an electrical synapse and a chemical synapse?
A
Electrical is within a neuron
Chemical is between neurons
8
Q
What do excitatory and inhibitory transmitters do and how do they affect action potentials?
A
Excitatory transmitters cause depolarization making the neuron more positive and increasing likelihood of action potential.
Inhibitory transmitters cause hyperpolarization making the neuron more negative and decreasing likelihood of action potential.
9
Q
What is convergence in terms of simple neural circuits?
A
output of circuit increases as length of stimulus increases
10
Q
What are the two surface features and four lobes of the brain?
A
Two surface features: sulci and gyri
Four lobes: frontal, parietal, temporal, occipital
11
Q
Where is the Sylvian fissure?
A
separates frontal and parietal from temporal
12
Q
Dorsal Orientation
A
Above
13
Q
Ventral Orientation
A
Below
14
Q
Lateral Orientation
A
Side
15
Q
Medial Orientation
A
Middle
16
Q
Anterior Orientation
A
Front
17
Q
Posterior Orientation
A
Tail
18
Q
What is the logic behind double dissociation and how does it help us understand the independence of two processes?
A
If damage to brain are A impairs function X but not Y, and damage to brain area B impairs Y but not X, these brain areas are functionally independent
19
Q
What is the manipulation and measurement of cognitive neuroscience?
A
Manipulation - cognitive processes
Measurement - brain activities
20
Q
What is the manipulation and measurement of brain perturbation?
A
Manipulation - brain functions
Measurement - task performance
21
Q
EEG - measurements, advantages, and disadvantages
A
Arrays of electrodes on the scalp to measure electrical activity of neurons
High temporal resolution
Low spatial resolution
22
Q
ERP - measurements, advantages, disadvantages
A
Time-locked average of EEGs
Good temporal resolution
Poor spatial resolution, source localization problematic (inverse problem)
23
Q
fMRI - measurements, advantages, and disadvantages
A
Measures changes in the amount of oxygenated blood
High spatial resolution
Low temporal resolution
24
Q
TMS (transcranial magnetic stimulation)
A
electromagnetic coil to temporarily disrupt local cortical functions
25
Differences between qualitative and quantitative methods
Qualitative: describing, recognizing
Quantitative: detecting/discriminating, perceiving magnitude
26
General procedure for method of adjustment
Stimulus intensity is adjusted continuously until observer detects it, repeated trials averages for threshold
27
General procedure for method of constant stimuli
Five to nine stimuli of different intensities are presented in random order, multiple trials are presented for each intensity, threshold is the intensity that results in detection in 50% of trials
28
General procedure for staircase method
A sequence of stimuli is presented, the intensity of which is stepped up or down depending on participants' response, threshold can be estimated by averaging the intensity at reversals in the staircase
29
What is a psychometric function?
relationship between perception and stimulus property
30
According to Fechner’s law, how does stimulus intensity relate to perceived intensity?
Perceived stimulus intensity is a logarithmic function of the physical stimulus intensity, JND grows larger as stimulus intensity increases
31
Steven's power law describes the relationship between physical intensity and perceived magnitude as a power function. What are the two response profiles?
Response compression (n<1), perceived magnitude (S) increases more slowly than intensity (I)
Response expansion (n>1), perceived magnitude (S) increases more quickly than intensity (I)
32
It can be difficult to measure absolute threshold because different individuals can have different response criteria. What are the two types of response criteria?
Liberal responder - responds yes if there is the slightest possibility of experiencing the stimulus
Conservative responder - responds yes only if they are sure that the stimulus was present
33
What is signal detection theory?
A theory about statistical decision making. It can be applied to decision making problems in which evidence being used to make a decision is a noisy (imperfect) indicator)
34
What are the procedures for a signal detection experiment?
A tone is presented to participant multiple times where they will produce one of four outcomes:
"Yes" when stimulus is present is a hit
"No" when stimulus is present is a miss
"Yes" when no stimulus is a false alarm
"No" when no stimulus is a correct rejection
35
How to calculate outcome rates of signal detection experiement
Hit Rate = # hits / # hits + # misses
FA Rate = # FA / # FA + # CR
36
Two underlying constructs of SDT: sensitivity and criterion
criterion - cutoff value determined by the person trying to detect the signal; measure as Hit + FA
sensitivity - measure as Hit - FA
37
What are some physical properties of light?
it is an electromagnetic wave, also a particle (light particle is a photon)
38
What are the anatomical structures of the eye in the order of light entering it?
Pupil, cornea, lens, retina
39
What is the property of convex lens?
For a fixed lens, a point light source closer to the lens will be focused further away from the lens; a higher curved convex lens will focus light at closer distance
40
What is the function of the cornea?
eye' major focusing element (~80% focusing)
41
What is the function of the lens?
changes in shape to focus at different distances (accommodation) (~20% focusing)
42
What is accommodation?
adjustment of lens shape so that a clear image is focused on the retina
43
Presbyopia - cause and solution
"old eye", distance of near point increases;
cause - due to hardening of lens and weakening of ciliary muscles
solution - convex lenses for close activities
44
Myopia - cause and solutions
nearsightedness - inability to see distant objects clearly
cause refractive - cornea or lens bends too much light
cause axial - eyeball is too long
solutions - move stimulus closer, corrective concave lens, surgery
45
Hyperopia - cause and solution
farsightedness - inability to see nearby objects clearly
cause - eyeball is too short
solution - corrective convex lens
46
What disorder does LASIK treat?
Can treat both myopia and hyperopia
47
What are the cells on the through pathway of the retina in the order that receives light?
photoreceptors, bipolar, ganglion
48
What cells are important for the lateral pathway?
horizontal, amacrine
49
What psychophysics method did Hecht and colleagues use?
method of constant stimuli
50
What (i.e. how many photons) did they find was the absolute threshold?
7 photons are absorbed by the pigment
51
What are the differences between rods and cones with respect to distribution on the retina, primary functions and adaptation times?
Rods:
Distribution - everywhere except fovea
Function - responsible for vision at low levels of illumination
Adaptation time - 30 min
Cones:
Distribution - everywhere, dense in fovea
Function - responsible for vision in high levels of illumination and color and detail vision
Adaptation time - 4 min
52
In dark adaptation experiments, how were experimenters able to isolate rods or cones?
Isolate cones - test light only stimulates cones (small test light in fovea)
Isolate rods - must use a rod monochromat (rare genetic defect where person has no cones)
53
Macular degeneration (retinal disease)
fovea and small surrounding area are destroyed, creates a "blind spot" on retina
54
Retina pigmentosa (retinal disease)
rods are destroyed first, foveal cones can also be attacked
55
How are the spectral sensitivities of photoreceptors measured?
Rods - measured under dark adaptation
Cones - measured at fovea (small stimulus)
56
What is the Purkinje shift?
enhanced sensitivity to short wavelengths during dark adaptation when the shift from cone to rod vision occurs
57
Photoreceptors converge in the retina before sending signals to retinal ganglion cells. Which type of photoreceptor has a higher convergence ratio?
Rods have a higher convergence ratio
58
How does convergence affect sensitivity and acuity?
Rods more sensitive to light than cones so greater convergence means more sensitivity
All-cone foveal vision results in high visual acuity, one-to-one wiring -> acuity
59
What is the definition of receptive field?
region of a sensory surface that, when stimulated, affects firing rate of a given neuron
60
What are two types of retinal ganglion cells (RGC) with center-surround receptive fields?
On-center, Off-surround - excited by light in center leading to increase in firing rate; inhibited by light in surrounding region, decrease in firing rate
Off-center, On-surround - inhibited by light in center leading to decrease in firing rate; excited by light in surrounding region, increase in firing rate
61
In lateral inhibition, which cells are excited by the photoreceptors?
horizontal cells
62
Which cells are inhibited by nearby receptors?
adjacent photoreceptors
63
How does lateral inhibition facilitate edge detection?
enhancing contrast and highlighting the boundaries between light and dark regions in the visual scene
64
How can lateral inhibition explain the shaper contrast around the edges when we look at the Mach bands?
by selectively inhibiting the activity of neighboring photoreceptors, which enhances the perception of contrast at the edges between regions of different brightness
65
When looking at the Hermann grid, most observers see a dark dot at intersections in the peripheral but not the central visual field. How does lateral inhibition explain that?
by selectively inhibiting the activity of neighboring photoreceptors, resulting in an exaggerated perception of contrast at the intersections in the peripheral visual field
66
What is an explanation for simultaneous contrast?
receptors stimulated by bright surrounding area send a large amount of inhibition to cells in center; receptors for dark send small amount
67
What are the brain areas involved in order in the pathway from retina to cortex?
Retina, optic nerve, lateral geniculate nucleus (LGN), primary visual cortex (striate cortex), two pathways to the temporal lobe and parietal lobe, frontal lobe
68
What is lateralization and how is it achieved in vision?
Specialization and processing of visual information occurs predominantly in one hemisphere of brain.
Achieved through the organization of visual pathways and processing of visual information in the brain
69
What are the three major types of RGC? Which cellular layers of the lateral geniculate nucleus (LGN) do they project to?
Midget -> parvocellular
Parasol -> magnocellular
Bistratified -> koniocellular
70
The retinotopic map represents spatial layout of retinal locations. How was the retinotopic map determined?
record from nearby neurons on a structure (e.g., LGN); adjacent neuron in the LGN have adjacent receptive fields on retina
71
What features are simple cells, complex cells and end-stopped cells in V1 responding to?
Simple cells - elongated center-surround (oriented bars of light or edges)
Complex cells - moving oriented bars or edges
End-stopped cells - moving oriented bars with corner
72
What is columnar organization?
neurons in a vertical column have a similar function/property
73
There are location, orientation, and ocular dominance columns in V1. For each of these columns, what does it mean for the cells in a single column?
Location - receptive fields at same location on retina are within a column
Orientation - neurons within columns fire maximally to the same orientation of stimuli
Ocular dominance - neurons in V1 respond preferentially to one eye
74
What was the ice cube model of orientation columns?
Hypercolumns - a single location column, left and right dominance, a complete set of orientation columns (0-180 degrees)
75
We know that V1 neurons are sensitive to specific orientations and contrasts. Why is activity from one neuron not enough to distinguish between orientations?
the brain needs a collective group of neurons and their interactions to distinguish visual stimuli
76
How does population coding resolve the problem for one neuron not being enough to distinguish between orientations?
the information is encoded by the combined activity of a group of neurons rather than a single neuron
77
Underleider and Mishkin demonstrated that the dorsal and ventral pathways are involved in different aspects of visual perception by inducing lesions in monkeys’ brains and asking them to perform a set of tasks. What did they find?
Ventral - "what" pathway; monkey with damage to temporal lobe failed to distinguish between object identities
Dorsal - "where" pathway; monkey with damage to parietal lobe failed to distinguish between locations
78
Patient DF, who sustained damage to her ventral pathway, struggled with orientation matching, but was able to insert an object into an oriented slot. What does this tell us about the old “what & where” model?
Dorsal seems to be a "how" pathway for visually guided actions
79
What is the definition of representation?
patterns of neural activity that gives information about a stimulus
80
What is the definition of recognition
process of matching the representation of a stimulus to a representation stored in a long-term memory
81
Image clutter - challenge OR
need to segregate objects from each other and from the background
82
Occlusion - challenge OR
objects can be covered by other objects, a type of clutter
83
Object variety - challenge OR
the number of shapes is virtually infinite
84
Variable views - challenge OR
objects look different from different viewpoints
85
What does the visual system use to extract edges?
luminance differential
86
How do we distinguish between figure and background?
border usually belongs to the figure
87
What are the Gestalt principles of perceptual grouping?
proximity, similarity, common motion, symmetry and parallelism, and good continuation
88
What are two types of perceptual interpolation and which of the challenges do they solve?
edge completion and surface completion solves occlusion
89
What is unconscious inference and the likelihood principle?
perceptions are result of unconscious assumptions about the environment
likelihood - objects are perceived based on what is most likely to have caused the pattern
90
How does the size of receptive fields (RF) change with increasing eccentricity?
RF size increases
91
How does the size of receptive fields change along visual pathway?
RF size increases
92
How does feature preference change along visual pathway?
in early stages of the pathway neurons prefer simple features and further along in higher stages they prefer complex ones
93
What does it mean to say that object representation in the brain is modular?
the brain has different modules which are brain structures that process information about specific stimuli
94
Are faces special? (evidence for)
Infants can track a moving face at just 30 min of age
Face agnosia without object agnosia
Inversion effect: normal subjects better at recognizing upright than inverted faces
Face selective cells in human MTL
95
Are faces special? (evidence against)
Face columns intermingle with other feature columns in human MTL
Face agnostics often show impaired recognition/discrimination ability for non-face objects within a category
Training effects with non-face stimuli
96
In the “greebles” experiment, what were participants trained to do? Activation in which brain area was measured and what did they find? What do the findings tell us about face perception (i.e. are faces special)?
Trained to recognize greebles by name
Activation in FFA (fusiform face area)
Faces are special
97
Environmental regularities (both physical and semantic) help scene perception. Give examples of both types of regularities.
Physical regularities - light in natural environment comes from above us
Semantic regularities - when looking at a scene like a kitchen, it is most likely to include objects like a stove, sink, fridge, etc. because it semantically is consistent
