NEUR530 - SENSORY Vision & hearing Flashcards
Differentiate between sensation and perception.
Describe visible light, hue, saturation, and brightness in the perception of light.
Identify the structures of the eye and describe their function in visual processing
Contrast the location and function of rods and cones.
Describe the process of transduction of visual stimuli.
Compare the characteristics of central and peripheral vision, including receptive fields and eye movements.
Explain how stimuli are conveyed to the brain through the optic nerves.
Describe the visual pathway, including the roles of the striate and the extrastriate cortex
- photoreceptors synapse with bipolar and retinal ganglion cells
- retinal ganglion cells send info to optic nerves and LGN in the thalamus
- the LGN send info to primary visual cortex, or V1 (occipital lobe)
- From V1, information is sent the visual association cortex or (V2)
- more complex aspects of visual processing may also travel on to additional cortical areas, such as V4 or V5
Describe the pattern of retinal ganglion cell input and the layers of the LGN.
Identify the role of the striate cortex in visual processing.
- first visual cortex region (V1)
- receives input from the LGN
- first region combining visual information
- necessary for visual perception
- transmits to the extrastriate cortex (V2)
- 25% is devoted to information from the fovea
Identify the role of the extrastriate cortex in visual processing, including the dorsal and ventral streams.
- consists additional regions (named V2–V5)
-contains neurons that respond orientation, movement, retinal disparity, color - passes the results on to “higher” regions for further analysis.
Compare how the trichromatic and opponent-color system theories explain color perception in the retina.
Describe the role of the striate cortex in color perception.
Describe the role of the extrastriate cortex in color perception
Describe the roles of the ventral stream and fusiform face area in perception of form.
Explain how the eyes, the striate cortex, and the extrastriate cortex contribute to the perception of spatial location.
Explain how cells in the striate cortex respond to orientation.
Cells will respond only when the line is in a particular position—a particular orientation. Some neurons respond to a vertical line, some to a horizontal line, and some to a line oriented somewhere in between. Figure 6.21 shows the responses of a neuron in the striate cortex when lines were presented at various orientations. As you can see, this neuron responded the most when a vertical line was presented in its receptive field.
Describe the roles of the extrastriate cortex in perception of movement.
What is sensation?
specialized cells detect environmental stimuli and transduce their energy into receptor potentials.
What is perception?
The conscious experience and interpretation of information from the senses.
What is hue ?
One of the perceptual dimensions of color; the dominant wavelength.
The visible spectrum displays the range of hues that our eyes can detect.
What is brightness ?
The perceptual intensity of colour
intensity of the electromagnetic radiation
What is saturation?
The perceptual purity of colour
What is sensory transduction?
-sensory stimuli are transduced into slow, graded receptor potentials.
What is receptor potential?
A slow, graded electrical potential produced by a receptor cell in response to a physical stimulus.
What is a rod?
Photoreceptor: sensitive to low light
What is a cone?
Photoreceptor- Sensitive to wavelengths of light and encodes color vision.
Is the retina and optic nerve part of the CNS or PNS?
CNS
The human retina contains approximately how many rods and cones?
92 million rods and 4.6
million cones
Does the fovea, central region of the retina, contain rods or cones?
cones only
What are 4 key things about cones and rods?
CONES:
1. `found in fovea
2. Sensitive to moderate and high levels of light
3. Hue information
4. Sharp
RODS:
- Peripheral retina
- Low levels of light
- Monochromic
- Poor sharpness
Retinal circuitry
Photopigments are embedded in the… what?
Lamellae
(thin plates of membrane that make up the outer segment of photoreceptors)
A single human rod contains approximately how many photopigment molecules?
10 million photopigment molecules
What 2 parts do photopigment molecules divide into?
an opsin (a protein) and retinal (a lipid)
Learn
To keep stimuli from the environment
projecting to the retina, particularly the fovea, the eyes make three types
of movements:
vergence
saccadic
pursuit
movements.
What are vergence movements?
cooperative movements that
keep both eyes fixed on the same target
What are vergence movements?
cooperative movements that
keep both eyes fixed on the same target
When you scan the scene in front of you, your gaze does not roam slowly and steadily across its features. Instead, your eyes make jerky movements… what are these called?
saccadic movements
PURSUIT movement: The movement that the eyes make to maintain an image of a moving object on the… what?
fovea.
What is the dorsal lateral geniculate nucleus (LGN)?
-Group of cell bodies within the thalamus
- receives input from the retina
- projects to the primary visual cortex.
The primary visual cortex is also called the … what?
striate cortex
because it contains a dark-staining layer (striation) of cells.
What is another name for the visual association cortex aka V2?
extrastriate cortex
because this region surrounds the striate cortex
The lateral geniculate nucleus contains how many layers of neurons?
6
What does LGN stand for?
Lateral Geniculate Nucleus (LGN)
What does the VENTRAL stream do?
- recognizes WHAT an object is and what COLOURS it has
What does the DORSAL stream do?
- recognizes WHERE the object is
- and its movement, speed and direction.
- Why was colour vision an advantage for our primate ancestors?
- distinguish between different types of food and to identify ripe fruit and leaves
- able to find and consume more nutritious food
- detect predators and avoid danger.
- better navigate their environment
Why are there three sets of cones?
- because each set of cones is sensitive to a different range of wavelengths of light.
- perceive a broad range of colors and shades
What are the 3 colour cones?
- red
- blue
- green
What are the 3 colour cones?
- red
- blue
- green
Area V5 of the extrastriate cortex—also known as?
area MT, for medial temporal
