0. Visual Processing in the Brain and Damage to the Visual Brain
Developed by the
SKI-HI Institute
Utah State University
Spring 2011
For use in VIISA
Training

1. The Visual Brain
The brain devotes more territory to vision than all other senses combined (40%)
There are 32 distinct areas in each hemisphere of the brain involved in visual processing.

2. Information Leaving the Retina
Retina: changes light energy to neural signals and performs computations on those signals, processing
Axons leaving the eye are heterogeneous, carrying different types of information:
spatial and depth
motion
color
lines and form
Some go to subcortical areas of the brain, leaving the main optic path before the LGN
Most continue to the LGN and on to the Visual Cortex

3. Key Subcortical Functions: SCN
Controls sleep-wake cycle
Production and release
of some hormones
Changing time zones,
neurons in SCN need
time to retrain to new
light-dark cycle
Implications for sleep problems in children who are blind

4. The Accessory Optic System (AOS)
3 separate nuclei in the brainstem
Project to the cerebellum and spinal cord
Play critical role along with vestibular and proprioceptive systems in:
-visual stabilization
-postural control
-regulating locomotion
and heading

5. Other Pathway Destinations
Superior Colliculus: Initiation and control of orienting movements of eyes, head and body to things in the peripheral fields and fixation on them
Some control pupil size
Some in brainstem to control eye muscles
Some in spinal column to control muscles in neck, trunk and limbs
Improved head and trunk control also often leads to
improved visual functioning

6. Lateral Geniculate Nucleus and V1
Projects to the cerebral cortex
Almost all the fibers terminate in the primary visual cortex or V1 area
All subcortical areas not only receive information from the eye but also the V1 area
They are also connected with each other as well as hearing and touch

7. Ventral and Dorsal Streams
Parietal Lobe
Frontal Lobe
Dorsal Stream
Visual Cortex
Temporal Lobe
Ventral Stream
Dr. Lea Hyvarinen Helsinki, Finland, 2004

8. Why do we need these two visual systems?
Visual Perception
Helps us make sense out of the outside world
Allows us to create representations of it that can be filed away for future reference
Guiding Action
Requires accurate information about actual size, location and motion
Has to be coded in the absolute metrics of the real world
Has to available in real time

9. Ventral Stream What? yellow Recognition of . . .  faces
 facial expressions
 colors & shapes
yellow
 letters and words
 animals
 objects
Recognition of landmarks for stored routes so we can remember how to get home from work. 13

10. Studying Brain Injury in the Old and the Young
We are learning a lot about how the visual brain works from adults who have suffered brain injuries from strokes, trauma, oxygen deprivation, etc.
They are able to talk about what and how they see in a way that young children with brain injury can’t.
Brain injury to young children may affect the visual brain in similar ways.
But in the very young child, brain plasticity may help the visual brain rewire to some degree around the lesions.
Depending on where, when or how much damage occurred, visual functioning may vary.
This is an exciting, emerging field of study.

11. Dee Case discussed in “Sight Unseen” by Goodale and Milner
Suffered carbon monoxide poisoning
A few days after the injury, she could walk, talk, hear, but not see.
Over time, regained conscious sight, but sight without form. She could not see edges or outlines of objects
Objects had to have a distinctive color, smell or texture for her to recognize them.
When she touched the object, she could then recognize it. 11

12. Dee’s Dorsal Stream Functioning
She could reach out and grasp a pencil accurately and use it.
She could use her hands well for many daily tasks.
She could get around her environment well.
She could hike over difficult terrain
Vision for perception was profoundly
affected and vision for action
unscathed.
lh3.ggpht.com

13. Dee’s Ventral Stream Function (15 years later)
Could not recognize short printed words on a page
Could not recognize faces or drawings and photos of every day objects
Trouble separating object from background: knife and fork next to each other were too similar and looked like a blob
Difficulty naming geometric shapes, even when on contrasting background; but when felt, she could name them
Could not copy simple pictures, but could draw from memory
Damage to her ventral stream had a profound impact on her visual functioning

14. Damage Can Be Specific to a Function
For example:
 Can not recognize a familiar face but can see it, reach for it, and touch the face
 Can match faces. . . but not be able to name who they are
 Acuity can even be normal
Dr. Lea Hyvärinen, Helsinki, Finland, 2004 18

15. Facial Recognition
Ways children compensate for loss of face recognition:
 May recognize people by their voice.
 May always ask who they are.
 If have problems with auditory recognition, may use other cues instead, for example:  color of shoes  smell.
Let the child use whatever compensatory technique works for them.
Sometimes, may need to teach slower child how to compensate. 20

16. Getting Lost in His Neighborhood
Little boy would get lost in his own neighborhood
Could not find best friend’s house even after repeated walks to it
Was not able to recognize, use, remember landmarks to help him find his way to and from
A ventral stream function
He had good acuity
Looking at alternative supports such as written directions for him to follow to get to places

17. Dorsal Stream Where?  orientation in space
 eye-hand, eye-foot coordination
 motion perception

18. Problems with Motion Perception
Rare and called akinetopsia
See stationary objects quite well
When object moves relatively quickly, they lose it
Woman who:
Difficulty pouring coffee into cup because she could not see liquid rising
Saw movement as a series of snapshots
Daily scenes looked like jerky, strobe-like movements

20. 27

21. 28

22. Problems with Motion Perception
Uncomfortable around . . .
 traffic
 fast moving small animals
 playgrounds

23. PEPI, The Dalmatian in Motion by Lea-Test Ltd. Copyright 200130

24. Perception of Objects in Space
If damaged, these children may . . .
 get lost easily
 have difficulty with accurate reach
 have difficulty with eye-hand/ eye-foot coordination (stepping on/off curbs, across sidewalk cracks, or changes in floor surfaces)
 difficulty in crowded situations
Dr. Lea Hyvärinen, Helsinki, Finland, 2004 31

25. Multiple Visual Tasks 32

26. Infants/Toddlers: One Thing at a Time
Visually being aware of multiple things takes time to develop and mature
Infants and toddlers focus on one thing at a time, and
may ignore the rest of the world
For some children, this skills may be delayed, so they may trip over, bump into things, fall off a curb when
focused on something they see at a distance, ignoring
the obstacles along the way
In the absence of an ocular disorder or CVI, this corrected itself over time, and the children were able to
handle multiple pieces of information.

27. Damage to the Parietal Lobe
 Visual array may need to be simplified
 Child may need to use a cane
 Child may need to move closer to block out background in order to simplify the visual array and focus on the single most important item 34

28. Damage to the Parietal Lobe
 Visual array may need to be simplified
 Child may need to use a cane
 Child may need to move closer to block out background in order to simplify the visual array and focus on the single most important item 35

29. Difficulty Scanning and Reading
Present small
numbers of words
at same time,
enlarged, show
them sequentially
How are you?
H o w a r e y o u ? H O W A R E
Difficulty following
movements
Difficulty scanning
the environment
A lot of print on
the page cannot
be seen at once
Moving head and
eyes accurately to
read is hard

30. Specific Problems Lesions to parietal lobe can result
From brain bleeds, strokes, etc.
Specific visual problems:
Loss of ability to direct the arm toward a visual target that they can look at
Reach to a target, but cannot direct gaze to it
Can see and reach to a target but not adjust grasp to it
images.teamsugar.com

31. Role of Other Lobes in Vision
Frontal lobe executes command
functions to visually attend to
objects and to turn eyes and
head in anticipation
Parietal lobe works closely with
frontal lobe and motor cortex to
do this
Damage to frontal lobe can make
it hard for child to decide what is
most important to focus on;
everything catches their attention
Motor Area
Parietal Lobe
Frontal Lobe
Simply and structure
the environment 38

32. Reticular Activating System
OT with SI
training can
provide ideas
for ways to
alert:
Movement
Massage
Music
Joint com-pression
Arousal and Wakeful-ness
Reticular activating system 39
Dr. Lea Hyvärinen, Helsinki, Finland, 2004

33. Organizing the Child for Using Vision
Reduce amount of incoming stimuli for child who is easily overwhelmed.
Help organize the visual system with massage, joint compressions, gentle movement, soothing sounds. 40

34. Ways Visual Information is Handled in the Brain
The reflexive or primitive visual system
The higher visual system
--Where
--What
Both of these high level visual systems can be damaged
to varying degrees with a wide array of affects seen.
Each child shows a unique combination of features
When primary visual cortex and processing centers are
damaged, vision problems occur (CVI) 43

35. Damage to the Brain and Vision Impairment
Focal damage to the visual brain leads to specific visual difficulties
Diffuse damage affects all aspects of brain function, including visual processing
Simple problems affecting visual acuity, field and contrast are easy to identify
Abnormal development of or injury to the optic radiations, visual cortex and visual processing areas (ventral/dorsal streams) result in vision problems
The role of perceptual and cognitive visual dysfunction in many other disabilities such as intellectual, autism, cerebral palsy, may not be recognized or understood.
Damage to the Brain and Vision Impairment

36. Acquired Neurological Injury: Hypoxic-Ischemic
Brain needs glucose and oxygen.
When deprived of one of these, potential
for long term brain dysfunction exists.
Asphyxia is lack of oxygen. Too little
oxygen (hypoxia) disrupts regulation of
blood supply to the brain, creating too
little blood flow (ischemia).
Severity and duration of episode
determines extent of damage
Organ damage, CP, seizures, hearing loss, CVI
When causes irritation to brain-encephalopathy
Numerous causes (e.g., PP, twin-to-twin, maternal diabetes or infection)
Can occur in utero, during birth, after birth; mostly in preterm newborns

37. Periventricular Leucomalacia
Most common neurological lesion in the preterm infant (24-34 weeks)
White matter damage in the watershed zones of the immature brain
Due to hypoxic-ischemic event-brief or profound impairment of blood flow to the area so no oxygen; preterm or perinatal-different
effects
Affects superior part of optic radiations
(result is lower field loss); subcortical
white matter that serves vision and association
areas (processing); oculomotor nerve damage
Wide range of visual and cognitive functioning
Field losses, visual/spatial problems, crowding
interpreting complex visual patterns.

38. Focal Brain Lesions
Includes such things as: arterial or venous stroke, intracranial hemorrhage, focal tumor
Nature and range of visual impairment depends on the location and extent of the lesions
At first, visual attending is poor, but usually acuity ends up OK, but there is field loss
Unilateral lesion behind optic chiasm may lead to homonymous field defect
Acuity is impaired when lesion is extensive or bilateral
Eyes move to target in blind hemifield, overshoot, then correct with microsaccades
Need to learn to scan
Central loss due to stroke, turn eyes away from field loss
Severe stroke can also lead to CP, seizures, delays

39. Intraventricular Hemorrhage (IVH)
Low birthweight premature babies may suffer brain bleeds in and around the ventricles
Germinal matrix is just outside the ventricles; incubator for brain cell production
In preterm, this area abundant in fragile blood vessels
Events causing too little or too much blood flow to area can lead to a bleed
Bleeds graded from I to IV (worst)
Optic radiations pass by and around the lateral ventricles
These bleeds can damage the optic radiations, resulting in vision loss
Severity of vision loss depends on the extent of the bleed, treatment, other medical issues, etc.
Grade III-IV bleeds can lead to CVI,
CP, hydrocephalus, delays
Lateral Ventricle
Optic
Radiations
Lateral Ventricle
(other views)
Grade III Bleed
in the Lateral
Ventricles

41. Traumatic Brain Injury
© VictorPowell.com
Shaken baby or accidents
Lead to: hemorrhaging, diffuse damage to axons, increased pressure in brain then hypoxic-ischemic events
Damage can be focal, multifocal or diffuse
The brain injury can result in CVI
At first, visual recovery may be rapid, but not complete
Optic nerve atrophy seen later, poor visual prognosis

42. Infections Other Occur before or after birth Neonatal Hypoglycemia
TORCH infections passed from mother to fetus (CMV, Herpes, rubella, toxo)
Result can be CP, seizures, CVI
Some ocular conditions such as cataracts can occur with these
CMV and meningitis can lead to vision and hearing loss
Vision loss can be CVI, optic nerve atrophy or nystagmus
Other
Neonatal Hypoglycemia
-if not treated, brain injury can
occur; results in poor cognition,
motor problems, epilepsy
High Bilirubin
-Chronically high; leads to hearing
loss, abnormal swallow and
speech, visual gaze problems
Metabolic Disorders
-mitochondrial, lysosomal and peri-
oxisomal
-CVI in context of neurlogical
deterioration along with many
other problems

43. Brain Malformations
Alterations in normal progression of brain development has neurological consequences
Include things like:
-Spina Bifida, Dandy Walker Syndrome
-microcephaly, lissencephaly,
schissencephaly, hydrocephalus
-agenesis of corpus calosum
Result from chromosomal disorder, infections, or idiopathic
Mild to severe developmental outcome
Present early with poor visual attention
May also see optic nerve anomalies, CVI, nystagmus, seizures
Lissencephaly

44. Optic nerve head in back child with hydrocephalus
Increased fluid in the ventricles or water spaces of the brain
Put pressure on optic nerve fibers; vision
transient or episodic due to vascular
dysfunction or hypertension in brain
Prolonged high pressure causes
permanent damage
Putting in shunt to drain fluid soon enough can minimize the damage
Decreased visual functioning can be a
sign of shunt failure
Acuity problems, strabismus, field loss, visual
perceptual problems
Child with Shunt
Optic nerve head in back
of the eye of 2 year old
child with hydrocephalus

45. Chromosomal Disorders
Trisomy 13 and 18
Common eye problems:
-microphthalmia
-coloboma
-abnormal optic nerve and eye
structures
-CVI
Epilepsy
Uncontrolled seizures, lead
to poor acuity and attention
Exclude diagnosis of infantile
spasms with infants who have
unexplained vision loss