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Psych 275 > Chapter 9: How Do We Sense, Perceive, and See the World > Flashcards

Chapter 9: How Do We Sense, Perceive, and See the World Flashcards

1
Q

Sensory receptors

A

-Specialized cells that transduce (convert) sensory energy (light) into neural activity
-Vision: Light to chemical
-Auditory: Air pressure to mechanical
-Somatosensory: Mechanical
-Taste/smell: Chemical molecules

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2
Q

Neural relays

A

-All receptors connect to cortex
-Information is modified at various stages allowing system to mediate different responses
-Neural systems allow the sensory systems to interact

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3
Q

Sensory coding

A

-Information encoded by action potentials that go from PNS to CNS
-Increase/decrease in discharge rate can encode stimulus intensity

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4
Q

Neocortex

A

-Represents the Sensory field of each modality: Vision, hearing, touch, smell and taste
-Topographic maps: Neural spatial representations of the world
-All mammals sensory systems have at least one primary cortical area

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5
Q

Sensation

A

-Bottom up processing
-Registration of physical stimuli from the environment by the sensory organs
-Vision is primary sensory experience

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6
Q

Perception

A

-top down processing
-Subjective interpretations of sensations by the brain
-Subjective reality curated by the brain

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7
Q

Electromagnetic energy

A

-Light is electromagnetic energy that we can see
-Range that is visible to humans:
400 nanometers violet, 700 red
-Shortest wavelengths=deep purple
-As wavelength increases: violet, blue, green, orange, red

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8
Q

Eye structure

A

-Cornea: Clear outer covering
-Iris: Opens/closes for light. Hole in iris is pupil
-Lens: Focuses light and bends to accommodate far or near
-Retina: Where light energy initiates neural activity

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9
Q

Retina

A

-Light-sensitive, back of the eye
-Has neurons and photoreceptors
-translates light to action potentials
-Discriminates wavelengths (colors)
-Works in wide range of light

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10
Q

Fovea

A

-Region at the center of the retina that is specialized for high acuity
-receptive field at the center of the eye’s visual field

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11
Q

Acuity across the visual field

A

-Vision is better in the center of the visual field than at the margins or periphery

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12
Q

Blind spot

A

-Region of retina (optic disk) where axons forming the optic nerve leave the eye and where blood vessels enter and leave
-Has no photoreceptors
-Optic disk is lateral to the fovea: Left of fovea in left eye etc..

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13
Q

Papilledema

A

-Swollen optic disk
-Due to high intracranial pressure (tumor or brain infection) or inflammation of the optic nerve (optic neuritis)
-Can cause loss of vision

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14
Q

Rods

A

-More numerous than cones
-Sensitive to low levels of light (dim light)
-Used for night vision
-One type of pigment only

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15
Q

Cones

A

-Highly responsive to bright light
-Specialized for color and high visual activity
-In fovea only
- 3 Types of pigment (trachoma)
-Absorbs light at different frequencies
-419 blue or short
531 green or middle
559 red or long

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16
Q

Types of retinal Neurons

A

1) Bipolar cell
2) Horizontal cell
3) Amacrine cell
4) Retinal ganglion cell (RBC)

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17
Q

1) Bipolar cell

A

-Receives input from photoreceptors

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18
Q

2) Horizontal cell

A

-Links photoreceptors and bipolar cells

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19
Q

3) amacrine cell

A

Links bipolar and ganglion cells

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20
Q

4) RGC

A

Gives rise to optic nerve

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21
Q

2 types of ganglion cells

A

1) Magnocellular cell (M-cell)
2) Parvocellular cell (P-cell)

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22
Q

1) Magnocellular cell (M-cell)

A

-Large
-Receives input from rods
-Sensitive to light and moving stimuli

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23
Q

2) Parvocellular cell (P-cell)

A

-Small
-Receives input from cones
-Sensitive to color (Ventral stream–> object color recognition

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24
Q

Optic Chiasm

A

-Junction of the optic nerves from each eye
-Axons from the nasal (inside) half of the retina cross over to the opposite side of the brain
-Axons from the temporal (outer) half of the retina remain on the same side of the brain
-Information from the left visual field goes to the right and vise versa

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25
3 Routes to the visual brain
1) Geniculostriate system 2) Tectopulvinar system 3) Retinohypothalamic tract
26
1) Geniculostriate system
-Projections from the retina to the lateral geniculate nucleus to the visual cortex -Stripes
27
2) Tectopulvinar system
-Projections from the retina to the superior colliculus to the pulvinar (Thalamus) to the parietal and temporal visual areas
28
3) Retinohypothalamic tract
-Synapses in the tiny suprachiasmatic nucleus in the hypothalamus -Roles in regulating circadian rhythms in the pupillary reflex -Directly to hypothalamus -Bottom up: Hypothalamus to the visual cortex (route 1)
29
Striate cortex
-Striped, different stripes within the stripes -Primary visual cortex -2 visual paths emerge from this cortex 1) Vision-related regions of the parietal lobe 2) Vision related regions of the temporal lobe
30
Dorsal visual stream
-Pathway that originates in the occipital cortex and projects to the parietal cortex -HOW PATHWAY (How an action is to be guided towards objects)
31
Ventral visual stream
-Pathway that originates in the occipital cortex and projects to the temporal cortex -WHAT PATHWAY ( identifies an object)
32
Geniculostriate pathway
-Lateral Geniculate nucleus (Thalamus) -Right LGN: input from right half of each retina -Left LGN: Input from left half of each retina -6 layers -P and M retinal ganglion cells send separate pathways to the thalamus
33
6 Layers of geniculostriate pathway
-1, 4, 6 input from contralateral retina -2, 3, 5 input from ipsilateral retina 1, 2 input from magnocellular cells -3, 6 input from parvocellular cells
34
Occipital cortex
-At least 6 visual regions -Primary visual cortex (V1: Striate cortex) -Striate cortex receives input from the lateral geniculate nucleus -Secondary visual cortex (V2-V5; extrastriate cortex) -Visual cortical areas
34
Tectopulvinar pathway
-Magnocellular cells from the retina project to the superior colliculus, which sends information to the pulvinar region of the thalamus -Medial pulvinar: Sends connections to parietal lobe -Lateral pulvinar: Sends connections to temporal lobe -Provides information regarding location: Where
35
Blob (V1)
-Region in the visual cortex that contains color-sensitive neurons -Revealed by staining for cytochrome oxidase -Heterogeneous layering
36
Interblob (V1)
-Region that separates blobs -Participates in perception of form and motion -Heterogeneous layering
37
Visual field
-Region of the visual world that is seen by the eyes -Divided into right and left -information in the left visual field goes to the right hemisphere and vise versa
38
Coding location
-Light on one place on retina will activate one ganglion cell and light in another area will activate a different cell -each RGC responds to stimulation on just a small circular patch of the retina: This is the cells receptive field
39
Lateral geniculate nucleus
-Cells in the LGN have visual fields -Each LGn represents a particular place -Projects to V1 forming a topographic map -Lager than RGC
40
Cortical tissue
-More tissue is devoted to cells in the fovea than in the periphery
41
Topographic organization of region V1
-Central part of visual field at the back of the brain -Peripheral areas of the visual field are located more anteriorly -The top part of the visual fields are represented in the lower part of the occipital lobe
42
Receptive fields hierarchy
-Receptive fields of many ganglion cells combine to form receptive field of 1 LGN cell -Receptive fields of many LGN cells combine to form receptive field of one V1 cell
43
Visual corpus callosum
-Connects the 2 hemispheres -Most of the frontal lobes are connected to one another -Occipital lobe have little connections. The only connections they have are the cells that lie along the midline of the visual fields--this makes receptive fields overlap
44
Neuronal activity of seeing shape
-Place straight line positioned at 45 degree angle in front of eye -Cell can respond to stimulus with either increasing or decreasing the firing rate -Cell could show excitation, inhibition or no reaction -Cell generates information of the line and responds selectively
45
Retinal ganglion cells
-Process complex information -Respond only to presence or absence of light -Concentric circle arrangement -Center and surround (periphery) -On center Vs off center cells
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-On center Vs off center cells
-On center: Excited when light falls on center portion of receptive field and inhibited when it falls in periphery: light across whole field produces weak excitation -Off center: Excited when light falls on the surround of the receptive field, inhibited when light falls in the center: Light across whole field produces weak inhibition
47
Overlapping receptive fields
-Neighboring retinal ganglion cells receive their inputs from an overlapping set of photoreceptors -Receptive fields overlap -Small spot of light shining on the retina is likely to produce activity in both on and off center ganglion cells
48
Luminance contrast
-Amount of light reflected by an object relative to its surroundings -This allows input from the RGC to tell the brain about the shape -Light VS dark contrast gives shadows
49
Processing shape in the V1
-V1 neurons receive input from multiple RGCs -Much larger receptive field than RGC -Cells behave like orientation detectors: Excited by bars of light oriented in particular directions -Simple cells VS complex cells VS hypercomplex cells
50
Simple cells VS complex cells VS hypercomplex cells
Simple cells: Receptive field with a rectangular on--off arrangement -Complex cells: Maximally excited by bars of light moving in a particular direction through the receptive field -Hypercomplex cells: Like complex cells, maximally responsive to moving bars, and strong inhibitory area at one end of the receptive field
51
3 dimensional view
-Sensory inputs enter the cortical column at layer V1 (bottom) and terminate on stellate cells in layer IV that synapses with pyramidal cells in layers lll and V. -Information flow is vertical -Axons of the pyramidal cells leave the column to join other columns or structures
52
Processing shape in temporal cortex
-Cells are maximally excited by complex visual stimuli (hands/faces) -May be selective to particular faces seen head on vs profile, head posture and facial expressions -Stimulus equivalence: Recognizing that an object is the same across different viewing orientations -Neurons with similar responsiveness to particular features tend to cluster in columns
53
Seeing color
-Subtractive color mixing obtains entire range of colors in visual world by only mixing 3 colors (red, blue yellow) -Additive color mixing increases light to make color, lighter color= more light it contains. This is why a white surface reflects the entire visible spectrum -Trichromatic theory -Opponent process
54
Trichromatic theory
-Explanation of color vision based on the coding of the three primary colors -Colors we see is determined by the relative responses of the different cone types -Explains different types of color blindness -Limiation that there are four basic colors (R, G, B, Y) and does not explain afterimages (red to green; blue to yellow)
55
Opponent-process
-Explanation of color vision that emphasizes the importance of the opposition of colors -Red V Green and Yellow V blue -Opponent processing occurs in RGC -On--off and center--surround receptive fields -About 60% of retinal ganglion cells
56
Opponent color contrast response
-Center of the receptive field is excitatory for some cells and inhibitory for other cells -Stimulation to the periphery has the opposite effect -Center is responsive to one wavelength and the surround is responsive to another
57
Opponent processes for neurons in cortical region V4
-Do not respond to particular wavelengths but are responsive to various perceived colors -Centers of the receptive field is excited by a certain color and the surround is inhibited -May be important for color constancy: Perceived color is constant relative to other colors, regardless of changes in illumination
58
Posterior parietal cortex
-Neuronal activity in the dorsal stream -Involved in processing visual information for action -HOW stream -Neurons in this stream are silent to visual stimulation when a person is under anesthesia -Some cells in this area process the visual appearance of an object to be grasped and these cells with fire even with a monkey watches another monkey picking up an object
59
Injury to pathway leading to cortex
-Monocular blindness -Homonymous hemianopia -Quadrantanopia -Scotoma
60
-Monocular blindness
-Destruction of the retina or optic nerve of one eye producing loss of sight in that eye -Tested by covering each eye
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-Homonymous hemianopia
Blindness of an entire LEFT or RIGHT visual field
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Quadrantanopia
Blindness of ONE QUADRANT of the visual field
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Scotoma
Small blind spot in visual field caused by a small lesion or migraines of the visual cortex
64
Injury to "WHAT" pathway
-Ventral stream -Agnosia: not knowing -Visual-form agnosia: Inability to recognize objects, cannot imagine or visualize -Color agnosia: Inability to recognize colors -Face agnosia: Inability to recognize faces
65
Injury to the "HOW" pathway
Optic ataxia: Deficit in the visual control of reaching and other movements -Damage to parietal cortex -Retention of the ability to recognize objects normally -Deficit in reaching for objects

Psych 275 (8 decks)

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