Visual system Flashcards
Name the 2 purposes of visual system
Brightness and motion detection
What is a visual field?
Area visable with eyes wihtout mvoing the head
Where is the center of vision?
Fovea
Looking with the fovea gives us ______?
This is the reason we scan as we take in info and why our eyes jump from place to place
visual acuity.
THe blind spot is where _____ exits into the brain
the optic nerve. Perceptual fill in occurs
Name the five types of neurons found in the retina and their purpose
- Bipolar cell-first relay info after transduction occurs
- Ganglion cell- form a bundle making the optic nerve
- Horizontal 4. amacrine- spread out the signal
- Rods and Cones-Transduction
Compare Rods characteristics to cones
Rods outnumber cones Rods are found in all parts of the retina except the fovea Rods are more sensitive to light Rods are larger and more densely packed Rods offer poor resolution
Compare cones to rods
Cones are concentrated in fovea
They are for acute vision and high resolution
Color vision
Track the 8 steps of the Geniculocalcarine tract
- Retina
- optic nerve
- Optic chiasm
- optic tract
- lateral geniculate nucleus
- optic radiations
- occipital or primary visual cortex
V1 is which Broadman’s area?
area 17
Secondary visual cortex, V2 and tiertiary visual cortex are which Broadman’s areas?
V2=18
V3=19
Track the ANS pathway of the light reflex
- light to eye
- optic nerve
- optic chiasm
- pretectal nucleus
- Edger Westbaum nucleus
- Occulomotor nerve
Leads to the constriction of pupil
What does the Superior colliculus do for vision?
Think of the TREX in jurasic park
monitors movement in periphery
controls saccadic eye movement
detects movement, position and contour of objects
Orients eyes to movement
Where is the inferior route of the frontal projections occur?
Posterior temporal lobe
What does the inferior route of frontal projections do?
It gives the “What” by combining with language and audition areas. Gets info from the fovea for lots of detail
What are the functions of the inferior route?
Object formation, classification, recognition,
attention to visual detail
Where is the superior route of frontal projection located and what does it do?
Parietal lobe. It gives you the where information. It integrates with proprioception, tactile, kinesthesia, vestibular and auditory inputs
What are the functions of the superior route of the frontal projections?
Orienting body position in space
Identification of objects in space, and their relationship to each other and the body
What do the frontal eye fields do?
Voluntary visual search of contralateral space based on an expectation of where visual information can be found
When does light perception occur?
7-8 months gestation
When does accomodation, convergence and binocular vision occur?
2-4 months
When does visual discrimination of faces and spatial mapping occur?
7-10 months
What are the developmental concerns in blindness
Potentially impaired milestones in: attachment and social communication preverbal communication low tone fear of movement Generally kids catch up around school age
List the order from bottom to top of Warren’s Visual Perceptual Hierarchy (there are 6)
- Foundational Skills
- Visual Attention
- Visual Scanning
- Pattern recognition
- Visual memory
- Visual Cognition
What are characteristics of Warren’s Visual Perceptual Hierarchy stage Foundational Skills?
Visual fields
Acuity
Oculomotor control
Coordination of eye and head movement
What are characteristics of Warren’s Visual Perceptual Hierarchy stage Visual Attention
Attention is engaged by novelty
Protective function: alert to changes in environment
Cognitive function: gathering information
What is homonymous hemianopia?
Loss of vision in either right or left half of each eye
What is non-homonymous hemianopsia?
Loss of temporal or nasal half of visual field
What are characteristics of Warren’s Visual Perceptual Hierarchy stage; Visual scanning
Scanning: saccadic eye movements
What are characteristics of Warren’s Visual Perceptual Hierarchy stage: Pattern Recognition
Subserves visual memory
Identifying salient visual features to support identification (general shape and contour, and specific features
What are characteristics of Warren’s Visual Perceptual Hierarchy stage: Visual memory
Create and remember in minds eye while engaging in analysis of objects
Storage and retrieval in short term memory
What are characteristics of Warren’s Visual Perceptual Hierarchy stage:Visual Cognition
Prefrontal functions
Forms foundations for academics
Characteristics of Cortical visual impairment
Disturbance of posterior visual pathways/occipital lobe
Deficits vary
Characteristics of visual perceptual deficits in adults
Often seen following a stroke, TBI, or other neurological disesases
3rd and 6th cranial nerve issues (occulomotor and abducens)
Could affect integration and interpretation
Could cause balance issues due to link with vestibular system
Characteristics of Perceptual problems in children
Letter reversals
Find reasons not to read
Complains that eyes hurt
Re-reads or skips lines
characteristics of visual motor deficits
Doesn’t leave enough space between words and letters
Letters are hard to determine
Difficulty coloring between the lines
Difficulty with fine motor tasks like cutting gluing and holding pencils
