Visual System Flashcards
The _____ is the point of fixation that has the highest visual acuity.
fovea (of the retina)
The optic nerve is part of _____ nervous system.
CNS
Partial crossing of optic nerve axons occurs at the optic _______ prior to forming the optic tracts.
optic chiasm
What is the fan of the lateral geniculate nucleus?
relay nucleus of thalamus
What are optic radiations?
fibers that arise from lateral geniculate nucleus
The visual cortex terminates adjacent to ______.
calcarine fissue
area 17
What is Area 17?
primary visual cortex
What are Area 18 and 19?
visual association cortex
color, movement, etc
Visual perception is processed in the ______ cortex.
occipital
After Central processing in the occipital cortex, information can flow via which two streams?
dorsal stream: motor control
ventral stream: conscious awareness of visual experience
Dorsal stream to the ______ cortex.
AKA?
posterior parietal cortex
“ambient vision”
Ventral stream to the _____ cortex.
AKA?
inferotemporal cortex
“focal vision”
The dorsal stream operates on information from:
fovea and retinal periphery
Describe dorsal stream qualities:
Can operate in dim light
Info used to guide ACTION
Info about characteristics of object
Describe ventral stream qualities:
Requires good lighting
Conscious perceptual experience of vision
Recognition of objects
The ventral stream operates on information from:
fovea
What is visual agnosia? Which stream?
VENTRAL STREAM LESION:
inability to recognize
How does optical ataxia present? Which stream?
DORSAL STREAM LESION:
- inability to reach in the right direction for objects
- inability to adjust grip to shape of object
Evidence for two streams is based on:
Perception-Action Dissociations
What is optical array?
pattern of light rays entering the eye
What info does optical array provide?
relative position of objects and self
Changes in optical array are called:
optical flow
Where is optical flow processed?
posterior parietal lobe
What is optical flow used for?
o Stability and Balance
o Velocity of movement of observer through the environment
o Direction of movement relative to position of fixed objects in environment
o Movement of objects relative to the observer
o Time to Contact between observer and object in the environment
______ is a crucial variable that brain uses to calculate motor requirements like catching a ball.
time to contact
