BIO T4 Flashcards
What is the role of the pretectum in the visual neural pathway?
reflex control of pupil and lens
What is the role of the superior colliculus in the visual neural pathway?
orienting the movements of head and eyes
What is the role of the hypothalamus in the visual neural pathway?
regulates the circadian rhythms
Where is the concentration of rods and cones the highest across the retina?
- Rods in the periphery and in between the fovea and blind spot
- Cones in the fovea
If you lost all of your cones, which of the following would likely occur?A) Loss of color visionB) Loss of peripheral visionC) Loss of night visionD) Loss of focused perception
A and D
| also light sensitivity
Lateral inhibition describes
the reduced activity in one neuron induced by a neighbouring neuron that is active
Which of the following statements best describes complex cells in the visual cortex?
a) They respond best to stationary stimuli.
b) They respond best to stimuli moving in a specific direction.
c) They are primarily involved in color perception.
d) They are sensitive to changes in brightness.
b
Which type of retinal cell is primarily responsible for transmitting visual information from photoreceptors to ganglion cells?a) Bipolar cellb) Complex cellc) Amacrine celld) Horizontal cell
a| receives input directly from the receptors
What is the primary function of end-stopped cells in visual processing?a) Detection of motionb) Perception of colorc) Recognition of facial featuresd) Detection of line orientation
d
group of ganglion cell axons that exit through the back of the eye
optic nerve
area at the back of the retina with no receptors
blind spot
tiny area of the retina specialized for acute, detailed vision
fovea
opening in the center of the iris where light enters
pupil
law of specific nerve energies
rule that whatever excites a nerve always sends the same information to the brain
ganglion cell
type of neuron in the retina that receives input from the bipolar cells
blind spot
area at the back of the retina devoid of receptors
neuron in the fovea of humans and other primates*
midget ganglion cell
chemical contained in rods and cones that release energy when struck by light
photopigment
horizontal cell
type of cell that receives input from receptors and delivers inhibitory input to*
thalamic nucleus that receives incoming visual information
lateral geniculate nucleus
receptive field
area in visual space that excites or inhibits any neuron
small cell body with small receptive field in or near the fovea
parvocellular neuron
large cell body with a large receptive field that is distributed evenly throughout the retina
magnocellular neuron
area responsible for the first stage of visual processing
primary visual cortex (area V1)
simple cell
cell that has a receptive field with fixed excitatory and inhibitory zones
blindsight
ability to respond in limited ways to visual information without perceiving it consciously
hypercomplex cell
cell that responds to a bar-shaped pattern of light in a particular orientation
strabismus
condition in which the eyes do not point in the same direction
What are cones for?
daytime lighting, or photopic conditions. 3 types of cones (with different photopigments)<img></img>
What are rods?
- nighttime lighting, or scotopic conditions.
- Higher photopigment concentration.
- More sensitive to light
- (with different photopigments)<img></img>
Are there rods or cones in the retina?
There are no rods in the central fovea, but there are manymore rods than cones in the peripheral retina
Explain the process of phototransduction
<img></img> In rod cells in the dark, sodium-potassium-pump is in a depolarised state due to cGMP (glutamate release)
–> When light hits rhodopsin channel, it activates transducin
–> activates phosphodiesterase
–> phosphodiesterase breaks down cGMP
–> hyperpolarised cell + decreased glutamate release
–> light stimulus! so rhodopsin is inactivated and via arrestin bound to rhodopsin transducin is blocked
–> cell becomes depolarised + glutamate release until the next light impulse hits
What is the reason for color vision deficiency?
People with certain genes fail to develop one type of cone,or develop an abnormal type of cone.
What’s the prevalence of colour blindness?
1 in 12* <img></img>
Which gene is responsible for red-green colour deficiency?
The gene causing red-green colordeficiency, is on the X chromosome.* <img></img>
What are parts of the parallel processing in the visual cortex?
- Ventral stream (towards temporal cortex): identifying and recognizing objects and faces.
- Dorsal stream (towards parietal cortex): important for identifying where the objects are.
What is the IT?
<img></img>: inferior temporal cortex recognizes objects –>
What’s visual agnosia
happens when the inferior temporal cortex is damaged and inhibits object recognition
What is the role of the fusiform gyrus
recognising faces –> damage: prosopagnosia
What is the MT?
Area MT: middle temporal cortex (=V5 area) –> responsible for processing visuospatial motion: inability to perceive or detect motion
What happens if V4 is damaged?
loss of color vision at the corresponding location in the visual field, visual attention and object recognition issues
What is the MST?
middle superior temporal cortex
* Motion perception
* Damage leads to motion blindness
Rods –
- nighttime lighting, or scotopic conditions. Higherphotopigment concentration. More sensitive to light.
vision in the fovea?
<img></img>
* daytime lighting, or photopic conditions. 3 types of cones (with different photopigments)<img></img>
In retinitis pigmentosa, early symptoms include the loss of peripheral vision and night vision. The loss of what type of cells couldlead to such symptoms?
rods
What about people with maculardegeneration, which symptoms dothey have?<img></img>
cones
Name the hidden parts
Name the hidden parts of the eye
Name the hidden parts of the eye
Which ten structures are part of the visual neural pathway?
- Eye
- Optic nerve
- Optic chiasm
- Hypothalamus
- Optic tract
- Pretectum
- Superior colliculus
- Lateral geniculate nucleus
- Optic radiation
- Striate cortex
What happened if I cut the optic chiasm in the middle?
I’d see the right visual hemisfield only with the left eye and the left visual hemisfield only with the right eye
What are the features of light?
What is astigmatism?
What is presbyopia?
What is myopia?
What is hyperopia?
What are the layers of the fovea?
What is the trichromatic theory?
We perceive colour through the relative rates of response by three kinds of cones, each one maximally sensitive to a different set of wavelengths.
Which cone is missing?
Image as viewed by an observer lacking green cones (deuteranomaly)
Which cone is missing?
Image as viewed by an observer lacking blue
cones (tritanopia)
Which cone is missing?
Image as viewed by an observer lacking red cones (protanopia)
What are the odds of inheriting colour deficiency?
The gene causing red-green color deficiency, is on the X chromosome.
Which visual cortex and other brain regions are implicated in vision?
How does visual information process from the V1?
What is the occipital lobe’s, temporal lobe and ventral stream role in vision?
explain the neurochemical processes underpinning vision
