Lecture 18 and 19: Visuospatial Disorders Flashcards
What are the Posterior Regions of the brain?
- Posterior Parietal
- Posterior Temporal
- Occipital lobes
Where is the anterior parietal lobe?
- It is the somatosensory cortex (Brodmann areas 3,1,2)
What are the functions of the anterior parietal lobe?
- Processes information about touch, pressure, vibration, joint sense
Where is the posterior parietal lobe?
- It contains the superior and inferior parietal lobules and is composed of all the parietal lobe that is not the anterior parietal lobe.
- In purple
What are the functions of the posterior parietal lobe?
- Integrates somatosensory information and visual information
- Codes for the organization of the body in space
- Allows for interaction with objects and/or tools in the environment
- Allows to produce movements and postures in space
What happens is a patient has a lesion on the posterior parietal lobe?
- Lose sense of where their body parts are situated in space
True or False
The anterior parietal lobe contains the supramarginal gyrus (area 40) and the angular gyrus (area 39).
False, these are located in the posterior parietal lobe
What happens if a patient has damage on their supramarginal gyrus?
- Develop
- deficits in body schema
- deficits in integrating information about position of the body in space
What is a Neuropsychologival evaluation?
- Used whenever a patient shos an specific deficit/symptom
- Interview and observation of behaviour using standard tests
- Provides normative quantitative data
What are the goals of a neuropsychological evaluation?
- Goals:
- Determine which problems bother the patient the most
- Understand the context in which the issue arises
- What is the patient’s attitude towards the problem
- What is the core issue
- Exclude competing diagnoses
What is a visuospatial disorder?
- They have to do with:
- Vision
- Space
- The affect spatial relationships between an observer and an object
What are some of the symptoms displayed by patient with visuospatial disorders?
- Some of the symptoms are:
- Difficulty in remembering spatial information and/or using it
- to guide behaviour
- perform mental spatial operations
- Low-level processing is normal
- Cognitive processing of visual and spatial information is impaired
- Difficulty in remembering spatial information and/or using it
Where do we commonly find the lesions in patients with visuospatial disorders?
- Dorsal, occipito-parietal projections of the visual system
What are the visuospatial disorders that we saw in class?
tba
What are the characteristics of disorders of sensory analysis and elementary perception?
- Impairment in the perception of orientation, position, distance and depth
- Not necessarily an impairment at the sensory level
- Lesions:
- posterior brain regions
What are the types of disorders covered in class that have to do with sensory analysis and elementary perception?
- Localization
- Depth perception
- Line orientation
- Visual disorientation
What is the disorder of localization?
- Difficulty in estimating location of objects
- Near the body, arm reaching distance
How can we test for impairments in localization?
-
perceptual matching task
- Patients are asked to compare pairs of visual stimuli with each other and make same/different judgements
What is the disorder of depth perception?
- Difficulty estimating depth
What is necessary to perceive depth?
- Requires monocular cues (colour perception and shading) and binocular cues (stereopsis)
- Binocular depth perception depends on the disparity between views of three-dimensional objects projected to each eye.
- Two images are used in the cerebral cortex and experienced as a single three-dimensional representation under normal circumstances
Case study on disorder of depth perception
- Photographer
- Symptoms:
- Difficulty discriminating depth, shade, colour/gray scale saturation perception
- Couldn’t look at objects clearly
- Damage:
- left occipital visual cortex
- subcortical area
- corpus callosum
- Tests:
- Color blindness (good)
- Spatial motion perception (good)
- Shape perception by shade (bad)
- Colour saturation perception (bad)
- Other
-
Prosopagnosia
- could discriminate outline of the face, he could not distinguish the different parts of the face
-
Prosopagnosia
From the MRIs of the case study involving the photographer, we noticed that the damage was in the “what” visual pathway. What does this mean?
That the “what” visual pathway may have some role in depth perception
What is the shape perception test by shade?
- Use shade to distinguish shape of objects
- Find the outline
What is the colour saturation perception test?
- Select the correct colour saturation grade in the color and gray scale images
Case study #2 in disorder of depth perception:
- Diagnosis:
-
Disturbance stereopsis
- Lesion:
- dorsal occipito-parietal region
- ventral occipito-temporal region
- Lesion:
-
Colour vision abnormalities
- Lesion:
- ventral occipito-temporal region
- Lesion:
-
Disturbance stereopsis
What is the disorder of line orientation?
Impairment discriminating between line orientation.
How does a normal human visual system behave with line orientations?
It is usually easier to discriminate horizontal lines from vertical lines (rather than oblique lines)
What is the oblique effect?
The fact that it is more difficult to discriminate oblique lines than vertical and horizontal lines for humans with normal visual system.
How can we test for line orientation disorder?
- Judgement of Line Orientation (JLO)
If a patient fails the JLO test, where do you think the damage is?
- Right posterior parietal and occipito-parietal regions within the dorsal visual stream
Describe the procedure of the JLO test
- Show card A
- Ask the patient to find the line(s) in card A in the template
What else can be assessed with the JLO test?
- Assess the patient’s performance on complex tasks of visual reasoning and visual construction
- This is since it deals with lines
- Evaluate complex abilities such as driving-related skills
How can JLO test be useful to study aging?
- Differentiate between normal elderly and demented subjects
- Demented:
- More problems with oblique lines compare with vertical, horizontal and oblique lines in other quadrants
- Demented:
What is a disorder of visual disorientation?
- Symptoms:
- Misjudging
- relative and absolute distances of objects from the body
- lengths and sizes
- Difficulty avoiding obstacles
- Misjudging
- Conserved:
- visual acuity and stereoacuity (can see depth)
- Lesions:
- Large lesions to the posterior brain regions (including occipital lobes)
What are the types of disorders of spatial cognition covered in class?
- Mental rotation
- Memory for location and spatial memory
- Maze learning
What is mental rotation?
- Ability to imagine movements, transformations or other changes in visual objects
What are the characteristics of disorder of mental rotation?
- Sensory perception and memory are normal
- Lesion:
- posterior brain region
- In some studies: right parietal region
How can we test mental rotation disorders?
- 32 stimuli
- 8 for each A, B, C and D
- Half black disc on right hand, other half black disc on left
- Question:
- Which hand is black disc
NOTE: Patients with right hemisphere lesions are selectively impaired in the inverted condition.
What is memory for location and spatial memory?
Ability to remember the location of a stimulus in space.
How can we measure short-term aspect of spatial memory?
- Corsi block span
- Recall location
What is the procedure in Corsi block span test?
- The experimenter taps a sequence of cubes
- The patient is asked to reproduce the same sequence
Note: patient do not see the numbers on the cubes
If a patient has problems with the Corsi block span test, which brain areas do you think are damaged?
- Parietal lobe
- Hippocampus
What is the procedure in the Recall location test?
- Patient is given card A
- Then, card A is put away and the patient is given a blank card. They are then asked to draw the dot at the same position as in card A
Note:
- This is a hard task.
- People without disorder are not very precise
- With disorder will be very imprecise
If a patient does poorly in the recall location task, where do you think the damage is?
Parietal damage
How can we test for long-term spatial memory?
- Kim’s game
What is the procedure of Kim’s game?
- Set dollar store items in random order, position and orientation on a table
- Ask the patient what each of the objects are and what their price might be
- Move the patient to another room
- Ask which objects they remember
- Ask to replace the same objects as they were in the other table
- 24 hours after repeat 4 and 5
What is the stylus maze task and what does it test?
- Tests memory location and spatial memory
- Procedure:
- patient has to attempt to find the path out of the maze by trying different directions from it’s current position.
- Whenever they “hit a wall” a buzzer would go off.
- The patient would then have to go back to the previous location and try another direction
- Diagonal directions are not permited
- Once the patient found the correct path, they are allowed to try again from the beginning.
- Through multiple trials, the number of errors (buzzing) is recorded
What does topography mean?
Physical features of an area of land.
Position of its elements.
What does topographical mean?
Relating to the arrangement or accurate representation of the physical features of an area.
What does topographical orientation mean?
It is the ability for individuals to find their way from one location to the other.
What do topographical disorders involve?
They are disorders that involve topographical orientation and memory.
Give some examples of topographical disorders.
- Loss of memory of familiar places
- Inability to read or draw maps
- Inability to find the way to their own house
- Inability to find the way to a given place in the external environment
- can’t learn new topological information
In what group of adults is it common to see topological disorders?
it is common in adults that have some brain damage and/or dementia.
True or False
Topographical disorders often co-occurs with other deficits.
If true, give examples of which deficits.
True
- Visual field loss
- Visual agnosia
- Unilateral spatial neglect
- Prosopagnosia
- Achromatopsia
- Visual and spatial memory impairments
- Posttraumatic amnesia and confusion
What does the cognitive aspect of navigation require?
- Recognition of landmarks
- Mental representation of spatial relationships
What is important to remember about topographical disorientation?
- Different deficits in different patients
- Different brain regions or different combinations of brain regions in different patients
What are some of the brain structures involved in navigation?
- Frontal and orbitofrontal cortex
- Temporal lobe cortex
- Fusiform and lingual gyri
- Parietal and retrosplenial cortex
- Sub-cortical structures
What is the role of the frontal and orbitofrontal cortex in navigation?
- High-level control of attention
- working memory
What is the role of the temporal lobe cortex in navigation?
- Specifically:
- parahippocampal gyrus
- hippocampal complex
- learning spatial information during navigation
- retrieving spatial information during navigation
What is the role of the Fusiform and lingual gyri in navigation?
Recognition of landmarks
What is the role of the Parietal and retrosplenial cortex in navigation?
- Spatial perception
- Tracking movement within the environment
What is the role of the subcortical structures in navigation?
Procedural memory
What happens if you damage your temporal lobe cortex?
- Deficient ability to learn paths in a novel environment
- Anterograde disorientation
What happens if you damage the parietal and retrosplenial cortex?
- Specifically:
- posterior parietal cortex:
- difficulties localizing the position of landmarks in the environment
- retrosplenial cortex:
- difficulty using landmarks to determine directions to the target
- posterior parietal cortex:
What happens if you damage the fusiform and lingual gyri?
Landmark agnosia
What are some of the compensatory strategies that patients might use to help with navigation?
- verbal directions
- Pay attention to distinctive features in the landscape
How can we test spatial relational information?
- Map drawing
- Locomotor map test
What does the locomotor map test involve? And were was the damage for patients who couldn’t do it?
- Damage:
- parietal lesions
- Have a card A with 9 points where the north is indicated
- Have to recreate the path in card B where the north is indicated in card A
- They can’t turn cad B
What are the categories of topographical disorders?
- Egocentric disorientation
- Heading Orientation
- Landmark agnosia
What is egocentric disorientation? Give an example.
- Inability to represent the relative location of objects with respect to self.
- A patient couldn’t say how long it takes to go from A to B. Even when they have done the path multiple times.
- Can describe the store
- Can’t point to object in his room while being blindfolded
What is heading disorientation? Give an example.
- Preserved landmark recognition
- inability to derive directional information from recognized landmarks
- Loss of sense of direction
- Example:
- Able to determine the current location
- Couldn’t determine what direction to head to next
- Remembers passing same place over and over again
- Example:
What is Landmark agnosia? Give an example.
- Distinguish different classes of landmarks
- Inability to recognize and use prominent features of landmarks for the purposes of orientation in familiar and novel environments.
- Inability to identify landmarks by their salient features
- Example:
- “My reason tells me I must be in a certain place yet I don’t recognize it.”
Name the case study that was about developmental topographical disorientation.
Iaria et al. 2009
What are the real-world navigation tests that were performed on the Iaria et al. 2009 case study?
- Route based navigation
- Landmark based navigation
- Verbal/instruction based navigation
- Using a map
What were the symptoms of the patient in Iaria et al. 2009?
- Normal language, cognitive and motor development
- Unable to orient in the environment
- No difficulty navigating their home
- Gets lost after leaving the hour
- Recognizes familiar places or environmental landmarks
- Follows strict stereotyped directions to get to work
- No difficulties in left-right discrimination or other visuospatial disturbances
What did the route based navigation test consist of?
- The patient and examiner would walk together from A to B.
- On the way back they would take a different path
- Patient would have to go from A to B as they did initially on their own
What did the landmark based navigation test consist of?
- The experimenter would point and name landmarks as they walked.
- On the way back, took a different path
- The patient would lead the experimenter through the initial path and name all the landmarks again
What did the verbal based navigation consist of?
- Each instruction included the name of the street to follow, the name of the street at which they needed to turn and the direction of the turn.
- Patient had to repeat path
Which of the real-world navigation tests did the patient in Iaria et al. 2009, passed?
- All of them
What test did Iaria et al. 2009 perform that the patient didn’t pass?
- The patient couldn’t read from a map.
- The selected path in the map was not the shortest
- Couldn’t determine the shortest path by looking at the map
- Made incorrect turn while using the map
Could the patient from Iaria et al. 2009, draw maps? Why, why not?
- Not really
- Errors in scaling and distances
- Rooms where in correct sequence
- CAN’T draw maps for less familiar environment (neighbourhood)
Can the patient from Iaria et al. 2009, draw maps? What does this tells us?
No, this suggests inability to form mental representation of the environment.
What was the main deficit of the patient in the case study Iaria et al. 2009?
Inability to form mental representations of the environment.
Why did the patient in Iaria et al. 2009, performed well in route based navigation and not so well in map based navigation?
Route based navigation requires procedural memory.
Map based navigation requires the cognitive map aka: mental representation of the environment
What type of learning does route based navigation uses? How is the route from A to B encoded?
It uses procedural learning which is encoded as a sequence of instructions or movements.
In other words, the environment is represented as a series of steps from A to B
Linear representation
What type of cognitive processe is used during map based navigation? How is the information encoded?
Map based navigation requires mental representation aka. Cognitive map.
It is a mental spatial representation of the environment
It contains the relationships, orientations and distances between landmarks.
Usually, becomes assessed when deviating from a habitual route.
What are the brain structures used for the cognitive map?
-
Hippocampus
- Acquiring and forming the cognitive map
-
Retrosplenial cortex bilaterally
- Forming and using the cognitive map
-
Frontal, parietal, temporal cortex
- Navigating the environment
What is the egocentric coordinate system?
- Body centered
- Used for route based navigation
- We need to know the position of salient landmarks with respect to our own bocy
What is allocentric coordinate system?
- Global invariant spatial relationship between landmarks which does not depend on where our body is in the space
- Used for Map-bases representation(cognitive map)
What are the brain regions involved in Egocentric coordinate system?
- Posterior parietal region
- Dorsal stream:
- Function: information for actions in space
- Most of the lesions include the superior parietal lobule in the right hemisphere
- Dorsal stream:
What are the brain regions involved in Allocentric information?
- Ventral, posterior temporal and occipital cortex
- Information needed for landmark identification
What is the virtual reality navigation task?
- The patient gets the chance to get familiar with the virtual environment by exploring with a joystick.
- Test:
- Start at some point A
- Get from A to B through the shortest route
- Results:
- After a lot of training, the patient from Iaria et al. 2009, was able to go from A to B through the shortest path
Given the performance of the patient of the Iaria et al. 2009, what can we say about their deficits?
- There was a deficit information of the mental map
- Needs overtraining
- No deficit in retrieval and use of the mental map
- Impairment was specific to the acquisition and not the retrieval of the cognitive map.
What is body schema?
- Personal awareness of one’s body
- location
- orientation
- Unconscious integrated neural representation of the body
- Representation of the body’s spatial properties:
- length
- segments
- arrangment
- configuration
What is body image?
- Conscious representation of the body coded by its sensory characteristics of quality, form and intensity.
- How we perceive our bodies
What are some disorders of body image?
- Bodily and auditory hallucinations
- Phantom limb
- Alice in Wonderland syndrome
What are the characteristics of a phantom limb?
- Patients can feel it moving and sometimes interacting with objects
- Sense of control and presence of the limbs in some people born without limbs
What are the characteristics of the Alice in Wonderland syndrome?
- Change in perception of the size of a body part
- No motor deficit observed
- Occurs in psychiatric and neurological conditions
- Hallucinations happen spontaneously and unpredictably
What is anosognosia?
- It is the verbal explicit denial of an illness
What is anosodiaphoria?
It is the lack of genuine concern about the deficit
What are the symptoms of anosognosia?
- Neglect or denial of paralysis
- Lack of appreciation of the extent of the defect
- Experience of a phantom limb
- Failure to distinguish between one’s own body and that of another
Why is anosognosia a problem?
- Impair a patient’s desire to seek medical help
- Impair desire to seek therapy or to benefit from therapy
What is hypochondriasis?
A physically healthy person is convinced of being ill.
What are some examples or subcategories of anosognosia?
- Anton’s syndrome
What is Anton’s syndrome?
- Denial of cortical blindness
- Pupils respond to light but the patient cannot demonstrate functional sight
- Cannot count fingers or discriminate objects, shapes or colors
- Deny having visual difficulties
- Guess the answer to questions
- When errors:
- makes excuses
- Visual hallucinations
- Loss of memory
- confused state
True or False
For patients with Anton’s syndrome, the anosognosia declines with time
True
What is the damage for patients with Anton’s syndrome?
- Bilateral calcarine cortex and visual association areas
- Frequent injury to the parietal and temporal lobes
What is hemiplegia?
It is the paralysis of one side of the body
Lesions: most often right hemisphere damage
Damage to frontal and parietal regions
What is personal orientation?
- The ability to locate body parts in response to:
- verbal instruction
- point to you right hand
- demonstration
- point to body part tapped by examiner
- markings on a schematic figure
- point to the body part which corresponds to the body part marked with number 2 on the diagram
- verbal instruction
What is autotopagnosia?
- inability to localize body parts on oneself and others with preserved ability to name body parts
What is pure autotopagnosia?
- inability to localize body parts on oneself only
What type of coordinate system does pure autotopagnosia have?
egocentric coordinate system
What part of the brain does autotopagnosia involve?
Superior parietal lobule in the left hemisphere
What is Finger agnosia?
- inability to differentiate the individual fingers or apply them to individual tools
- automatized activities are preserved
- cannot use specific finger on instruction
- (lesion in parietal right?)
What is Right/Left Disorientation?
Inability to distinguish left or right on the self or on other people or on a schematic figure.
