Behavioral Neuroscience: Exam 2 Flashcards
1
Q
Two Types of Research Needed to Study Vision
A
- Research probing the components of the visual system
2. Research assessing what we see
2
Q
Light can be thought of as…
A
- Particles of energy (photons)
- Waves of electromagnetic radiation
*Humans see light between 380-760 nanometers
3
Q
Pupil
A
Light enters the eye through the pupil, whose size changes in response to changes in illumination.
4
Q
Sensitivity
A
The ability to see when light is dim.
5
Q
Acuity
A
The ability to see details.
6
Q
Lens
A
Focuses light on the retina.
-Ciliary muscles alter the shape of the lens as needed
7
Q
Accommodation
A
The process of adjusting the lends to bring images into focus.
8
Q
Iris
A
Colored part of the eye. A specialized muscle flexes and relaxes to either open or close down the pupil.
9
Q
Cornea
A
Sensitive membrane that holds fluid inside of the eye.
10
Q
Sclera
A
Tough protective outer membrane of the eye.
11
Q
Ocular Muscles
A
When these muscles move they roll the eye around the head and they attach to the tough outer layer of the eyeball.
12
Q
Retina
A
Where transduction occurs. Transducers physical energy into electrochemical energy.
- The retina is in a sense “inside-out”
- Light passes through several layers before reaching its receptors
13
Q
Fovea
A
Place of highest acuity on the retina - the place where you get the most detail.
14
Q
Convergence
A
Eyes must turn slightly inward when objects are close.
15
Q
Binocular Disparity
A
Difference between the images on the two retinas.
16
Q
Vertical Pathway
A
Pathway of light through the layers of the retina - it flows both directions, photons flow in and action potentials flow out.
It has 3 primary layers:
- Receptors
- Bipolar Cells
- Retinal Ganglion Cells.
17
Q
Blind Spot (Optic Disk)
A
No receptors where information exits the eye - the visual system uses information from cells around the blind spot for “completion”, filing in the blind spot.
18
Q
Cones
A
- Photoscopic (daytime) vision
- High acuity color information in good lighting
- Only cones are found at the fovea
19
Q
Rods
A
- Scotopic (nighttime vision)
- High sensitivity, allowing for low acuity vision in dim light, but lacks detail and color information
- More convergence than the cone system, increasing sensitivity while decreasing acuity
20
Q
Spectral Sensitivity Curve
A
Shows the relationship between wavelength and brightness
21
Q
Transduction
A
Conversion of one form of energy to another
22
Q
Visual Transduction
A
Conversion of light to neural signals by visual receptors (photons to action potentials). Pigments absorb light.
23
Q
Absorption Spectrum
A
Describes spectral sensitivity.
24
Q
Retinotopic Organization
A
- Information received at adjacent portions of the retina remains adjacent in the striate cortex.
- More cortex is devoted to areas of high acuity - like the disproportionate representation of sensitive body parts in the somatosensory cortex.
- About 25% of primary visual cortex is dedicated to input from the fovea
25
Magnocellular Layers
- Big cell bodies, bottom two layers of the lateral geniculate nucleus
- Particularly responsive to movement
- Input primarily from rods
26
Parvocellular Layers
- Small cell bodies, top four layers of the lateral geniculate nucleus
- Color, detail, and still or slow objects
- Input primarily from cones
27
Mach Bands
Nonexistent stripes the visual system creates for contrast enhancement. Makes edges easier to see.
28
Receptive Field
The segment of the visual field for which an individual receptor is responsible.
29
Component Theory
(Trichoromatic Theory)
| - 3 types of receptors, each with a different spectral sensitivity
30
**Name the Sensory Receptors of the Nervous System**
1. Red Cones
2. Blue Cones
3. Green Cones
4. Rods
31
Color Constancy
Color perception is not altered by varying reflected wavelengths.
32
Retinex Theory
Color is determined by the proportion of light of different wavelengths that a surface reflects.
33
Scotoma
Areas of blindness in contrlateral visual field due to damage to primary visual cortex. Detected by oerimetry test.
34
Blindsight
Response to visual stimuli outside conscious awareness of "seeing". Possible explanations of blindsight:
- Islands of functional cells within scotoma
- Direct connections between subcortical structures and secondary visual cortex, not available to conscious awareness
35
Dorsal Stream
Pathway from the primary visual cortex. The "where" pathway (location and movement), or the pathway for control of behavior (e.g. reaching).
-Specializes in visual spatial perception and visually guided behavior
36
Ventral Stream
Pathway from primary visual cortex to ventral prestriate cortex to inferotemporal cortex. The "what" pathway (color and shape), or the pathway for conscious perception of objects.
-Specializes in visual pattern recognition and conscious visual perception
37
Prosopagnosia
- The inability to distinguish among faces. Most prosopagnosic's recognition deficits are not limited to faces.
- Prosopagnosia is associated with damage to the ventral stream between the occipital and temporal lobes.
- Prosopagnosics may be able to recognize faces in the absence of conscious awareness. They have different skin conductance responses to familiar faces compared to unfamiliar faces, even though they reported not recognizing any of the faces.
38
Primary Sensory Cortex
Input mainly from thalamic relay nuclei.
39
Secondary Sensory Cortex
Input mainly from primary and secondary cortex within the sensory system.
40
Association Cortex
Input from more than one sensory system, usually from secondary sensory cortex.
41
*Functional Segregation*
Distinct functional areas within a level.
42
*Parallel Processing*
Simultaneous analysis of signals along different pathways.
43
*Hierarchical Organization*
Specificity, Sensation, Perception
44
The Hierarchical Organization of the Sensory Systems
- Association Cortex (most complex)
- Secondary Sensory Cortex
- Primary Sensory Cortex
- Thalamic Relay Nuclei
- Receptors (flow of information begins here)
45
*The Hierarchical Organization of the VISUAL System (Stop Sign)*
1. Rods & Cons (receptors)
2. Lateral Geniculate Nucleus (thalamus)
3. Primary Visual Cortex (shape, color size)
4. Secondary Visual Cortex (It's moving towards me, white edges)
5. Name it as you consciously see it (association cortex) (it's a stop sign, it's moving towards me, I need to stop, move my foot to the break)
46
Auditory System
Natural sounds are complex patterns of vibrations. Natural sounds are broken down into sine waves by a Fourier analysis. There is a complex relationship between natural sounds and perceived frequency.
47
Amplitude
The larger the stimulus = Loudness
48
Frequency
How fast a stimulus bounces back and forth = high pitch/ low pitch
49
Complexity
How many frequencies and amplitudes you have going on at the same time. More complex = more timbre (how much information is carried in the sound)
50
The Ear
Sound waves enter the auditory canal of the ear and then cause the tympanic membrane (the eardrum) to vibrate. This sets in motion the bones of the middle ear, the ossicles, which trigger vibrations of the oval window.
51
Middle Ear
The occicles: Hammer, anvil and stirrup. Latin names = extra credit
52
Pinna
The ear lobe. Purpose is to capture as many air molecules as possible and direct them into the ear canal.
53
5 Senses
1. Taste & Smell
2. Sight
3. Sound
4. Touch
5. Vestibular Sense (Body position, balance)
54
Corti
Combosed of the basilar membrane (auditory receptors and hair cells) and the tectorial membrane (rests on the hair cells).
-Stimulation of the hair cells triggers action potentials in the auditory nerve.
55
Anterior Stream
May be more involved in identifying sounds ("what").
56
Posterior Stream
May be more involved in locating sounds ("where").
57
Hierarchical Organization
Association cortex at the highest level, muscles at the lowest.
- Parallel Structure: Signals flow between levels over multiple paths
- Motor output is guided by sensory input
58
Sensorimotor Association Cortex
1. Posterior parietal association cortex
2. Dorsolateral prefrontal association cortex
- Each composed of several different areas with different functions
59
Sensory System Organizarion
Integrates information about:
- Body part location
- External objects
- Receives visual, auditory, and somatosensory information
60
Damage to the Posterior Parietal Cortex
- Apraxia
| - Contralateral Neglect
61
Apraxia
Disorder of voluntary movement - problem only evident when instructed to perform and action - usually a consequence of damage to the area on the left.
62
Contralateral Neglect
Unable to respond to stimuli contralateral to the side of the lesion - usually seen with large lesions on the right.
-Only shaving one side of their face, only applying makeup to one side of their face
63
Dorsolateral Prefrontal Association Cortex
Evaluates external stimuli and initiates voluntary reactions - supported by neuronal responses.
64
Secondary Motor Cortex
- Input mainly from association cortex
- Output mainly to primary motor cortex
- May be involved in programming movements in response to input from the dorsolateral prefrontal cortex
- Active during imagining or planning of movements
65
Mirror Neuron
Active when performing an action or watching another perform the same action
-Possible neural basis of social cognition
66
Primary Motor Cortex
- Precentral gyrus of the frontal lobe
- Major point of convergence of cortical sensorimotor signals
- Major point of departure of signals from cortex
67
Somatotopic
More cortex devoted to body parts that make complex movements
-Motor homunculus
68
Cerebellum and Basal Ganglia
- Interact with different levels of the sensorimotor hierarchy
- Coordinate and modulate your movements
- May permit maintenance of visually guided responses despite cortical damage
69
Cerebellum
- 10% of brain mass, but more than 50% of its neurons
| - Involved in timing, fine-tuning, and motor learning
70
Basal Ganglia
- A heterogenous collection of interconnected nuclei
| - Modulate motor output and cognitive functions including learning
71
Two Dorsolateral Pathways (Back)
1. Corticospinal (direct)
| 2. Corticorubrospinal (indirect)
72
Two ventromedial Pathways (Front)
1. Corticospinal (direct)
| 2. Cortico-brainstem-spinal tract (indirect)
73
Slide #30
A General Mode of Sensorimotor System Function
