7- Recovery from Visual Brain Damage

Question 1

general organisation of brain

Question 2

The Visual field:
Horizontal range in one eye is how many degrees?

Answer 2

160 degrees
(60 deg. nasal field; 100 deg. temporal field)

Question 2

The Visual field:
The full horizontal range of the human visual field is a slightly more than how many degrees?

Answer 2

180 degrees

Question 3

The Visual field:
The vertical range is how many degrees?

Answer 3

135 degrees
(60 deg. upper field; 75 deg. lower field)

Question 4

Mapping the visual field:

Visual field tests use static or kinetic perimetry to detect dysfunction in central and peripheral vision caused by various medical conditions (P identify a change in the luminance of specific location)

What are the 2 types of mapping?

Answer 4

Static perimetry
Present static light target (a person is fixating on) of different intensity at different positions in visual field
or

Kinetic perimetry
moving light target towards centre of vision from periphery

Determine threshold for detecting light at different positions (static perimetry) or visual field sensitivity boundaries (kinetic perimetry)

Question 5

Deficits in the visual field produced by
lesions at various points in the visual pathway:
What damage will happen to area 1 which has a lesion of the right optic nerve?

Answer 5

total loss of vision right eye

Question 6

Deficits in the visual field produced by
lesions at various points in the visual pathway:
What damage will happen to area 2 which has a lesion of the optic chiasm?

Answer 6

loss of vision in temporal halves of both visual fields
(bilateral hemianopia)
as infor that is crossing cannot be relayed

Question 7

Deficits in the visual field produced by
lesions at various points in the visual pathway:
What damage will happen to area 3 which has a lesion of the optic tract?

Answer 7

complete loss of vision in opposite half of visual field
(contralateral hemianopia)
as it has crossed the chiasm

Question 8

Deficits in the visual field produced by
lesions at various points in the visual pathway:
What damage will happen to area 4 which has a lesion of optic radiation (Meyer’s loop) causes?

Answer 8

loss of vision in upper quadrant of opposite half of visual field of both eyes

(upper contralateral quadratic anopia)

Question 9

Deficits in the visual field produced by
lesions at various points in the visual pathway:
What damage will happen to area 5 and 6 which both have partial lesions of visual cortex?

Answer 9

partial visual field deficits on opposite side

Question 10

Which term does this describe?

Lesion of optic chiasm (1) causes loss of vision in temporal halves of both visual fields

Answer 10

bilateral hemianopia

Question 11

Which term does this describe?

Lesion of optic tract (2) causes complete loss of vision in opposite half of visual field

Answer 11

contralateral hemianopia

Question 12

Which term does this describe?

Lesion of optic radiation (Meyer’s loop) causes loss of vision in upper quadrant of opposite half of visual field of both eyes

Answer 12

upper contralateral quadratic anopia

Question 12

Lesion of optic radiation that causes loss of vision in upper quadrant of opposite half of visual field of both eyes (upper contralateral quadratic anopia) is also known as what term?

Answer 12

Meyer’s loop

Question 12

Damage to primary visual cortex can cause …

Answer 12

cortical blindness

Question 13

Lesions that destroy primary visual cortex (V1) cause dense cortical blindness by depriving cortex of which type of information?

Do cortical blind individuals lose all visual abilities within their blind field?
Some patients have residual sensitivity without consciousness – termed “blindsight”

Answer 13

bottom-up sensory information

Question 13

Damage to primary visual cortex can cause cortical blindness.
Do cortical blind individuals lose all visual abilities within their blind field?

Answer 13

they do not lose all visual abilities within their blind field

Some patients have residual sensitivity without consciousness = “blindsight”

Question 14

Some patients have residual sensitivity without consciousness = “blindsight” which means they do not lose all visual abilities within their blind field.

Residual visual functions vary considerably among cortically blind patients, most likely due to … of damage to cortex?

Answer 14

amount and location

Question 15

Damage to the dorsal stream can cause …

Answer 15

motion blindness

Question 15

Despite residual visual processing abilities in the blind field, cortically blind patients still severely impaired at everyday visual functions such as …?

Answer 15

reading and navigating in unfamiliar environments

These visual impairments are primarily responsible for the significant decrease in quality of life reported by V1-damaged patients

Question 16

Damage to the ventral stream can cause?

Answer 16

face blindness

Question 17

Which term is used to describe the disorder of which people cannot identify faces, even familiar faces, but can recognize a face as being a face?

Answer 17

Prosopagnosia

Damage to the ventral stream
Lesion site is fusiform gyrus, predominantly in the right hemsiphere (can be bilateral)

Popularised by Oliver Sacks in his book “The Man Who Mistook His Wife for a Hat”
No therapies have demonstrated lasting read-world improvements

Question 18

Is Prosopagnosia acquired and congenital (developmental) forms exist?

Answer 18

both

Question 19

Which disorder is given to people who lose their ability to perceived visual motion following a lesion to extrastriate cortex (V5 or MT+)?

Answer 19

Cerebral Akinetopisa

Question 20

Which disorder explains the following symptoms: -Could not see movements of objects, but could recognize objects -Could judge motion using other senses (e.g. tactile, auditory) -Moving stimuli appears as static frames (as seen through a strobe slight)

Answer 20

Cerebral Akinetopisa (dorsal stream damage)

Question 20

The impaired ability to visually recognize objects (apperceptive and associative) caused by damage to ventral stream (IT) is known as?

Answer 20

Visual agnosia

Question 21

Deficits in the visual field produced by lesions at various points in the visual pathway are known as?

Answer 21

Visual field deficits

Question 22

The impaired ability to recognize familiar faces caused by damage to fusiform gyrus is known as?

Answer 22

Prosopagnosia

Question 22

Damage to primary visual cortex causes cortical blindness with some residual unconscious vision is known as?

Answer 22

Cortical blindness (“blindsight”)

Question 23

Colour blindness caused by damage to cortex in ventral stream (V4) is known as?

Answer 23

Cerebral achromatopsia

Question 24

(The inability to perceive the visual field as a whole, difficulty in fixating the eyes, and the inability to move hand towards objects under visual guidance is known as which disorder?

Answer 24

Bálint’s Syndrome

Question 25

(Visual) Brain injury cascade: What are the 2 distinct phases after brain injury which ultimately lead to cell death?

Answer 25

Phase One Primary insult or injury, -direct tissue damage -impaired cerebral blood flow -impaired metabolic activity -leading to edema formation (sweating around affected brain region area) -cytoarchitecture changes Phase Two Secondary injury, setting in motion a cascade of pathophysiological processes -loss of cell homeostasis (ability for cells to maintain a specific balance is lost) -calcium and sodium ion release -neurotransmitter release -excitotoxicity (extreme spiking/ levels of activity within injured region) -breakdown of blood-bran barrier (pathogens can now enter the brain)

Question 26

Which phase of brain death does the following characteristic belong in? -loss of cell homeostasis (ability for cells to maintain a specific balance is lost)

Answer 26

phase 2

Question 27

Which phase of brain death does the following characteristic belong in? -impaired metabolic activity -leading to edema formation (sweating around affected brain region area)

Answer 27

phase 1

Question 28

Which phase of brain death does the following characteristic belong in? -direct tissue damage -impaired cerebral blood flow

Answer 28

phase 1

Question 29

Which phase of brain death does the following characteristic belong in? -neurotransmitter release -excitotoxicity (extreme spiking/ levels of activity within injured region) -breakdown of blood-brain barrier (pathogens can now enter the brain)

Answer 29

phase 2

Question 30

Which phase of brain death does the following characteristic belong in? -cytoarchitecture changes

Answer 30

phase 1

Question 31

Which type of recovery happens to the affected brain areas during a period of 3-6 months after injury?

Answer 31

Spontaneous recovery

Question 32

info pic

Answer 32

brain injury recovery

Question 32

Which type of recovery happens to the affected brain areas after the period of 6 months after injury?

Answer 32

Training-induced recovery

Question 32

Which type of recovery do these all fall under? Diaschisis reversal – inflammation, blood flow, metabolic changes begin to subside Changes in kinematics – compensatory eye movements towards affected hemifield Cortical reorganization - within-area and between-area rewiring of brain circuits

Answer 32

Spontaneous recovery

Question 33

Which type of recovery do these all fall under? Recruitment – brain areas not involved pre-injury contribute to function post-injury Retraining – training of residual brain areas, cortical reorganization, and compensation

Answer 33

Training-induced recovery

Question 34

Which type of recovery is this: inflammation, blood flow, metabolic changes begin to subside

Answer 34

Diaschisis reversal (Spontaneous recovery)

Question 35

Which type of recovery is this: compensatory eye movements towards affected hemifield

Answer 35

Changes in kinematics (Spontaneous recovery)

Question 36

Which type of recovery is this: within-area and between-area rewiring of brain circuits

Answer 36

Cortical reorganization (Spontaneous recovery)

Question 37

Which type of recovery is this: training of residual brain areas, cortical reorganization, and compensation

Answer 37

Retraining (Training-induced recovery)

Question 37

Visual discrimination training recovers visual functions in chronic cortically-blind (CB) fields: info slide

Answer 37

Most change occurs at border of scotoma

Question 37

Which type of recovery is this: brain areas not involved pre-injury contribute to function post-injury

Answer 37

Recruitment (Training-induced recovery)

Question 38

What are the potential mechanisms of training-induced visual recovery after V1 damage?

Answer 38

1- Training induces plasticity in spared cortex proximal to lesion (island of spare cells which we train to try and expand their function) 2- Training strengthens neural pathways/ networks that bypass V1 and project to extrastriate cortex 3- Training recruits or inhibits visual areas in the intact hemisphere (the other hem takes over the damaged one)

Question 38

Spontaneous plasticity after damage to primary visual cortex: info slide

Answer 38

Damage to V1 (like damage to any part of the brain) is usually followed by some amount of spontaneous recovery In visual field deficits, 50-60% probability of spontaneous visual improvements in first month after lesion, but little improvement after 3 months and none after 6 months Most of the spontaneous recovery is thought to be due to reduction in inflammation and edema around the lesion and reactivation of partially damaged tissue near the lesion Patients compensate for vision loss with gaze strategies that are both normal and abnormal and biased toward the affected hemi-field

Question 39

Damage to middle temporal cortex in the dorsal stream causes motion blindness which is also known as?

Answer 39

akinetopsia

Question 40

After brain injury, there are two distinct phases - primary followed by secondary injury with different pathophysiological profiles Two stage process to recovery from acquired brain injury – spontaneous and training induced recovery Following cortical blindness, there is a period of ... after which the visual deficit stabilizes and becomes permanent in the absence of specific intervention?

Answer 40

spontaneous plasticity

Question 41

What are The three potential routes for training to induce visual recovery after V1 damage

Answer 41

induce plasticity in spared cortex proximal to the lesion strengthen neural pathways that bypass V1 and project to extrastriate cortex recruit or inhibit visual areas in the intact hemisphere