Movement Disorders Flashcards
Define Apraxia
Disorder of Skilled Movement
List traits that are NOT caused by Apraxia
1) Impaired primary motor ability
- weakness, akinesia, deafferentation
- abnormal tone or posture, primary movement disorder
2) Impaired comprehension
In right handers where are the focal lesions associated with?
The left hemisphere
Right hand is often paralyzed
- Often have hemiplegia; test it in left (nondominant) hand
What are the 4 types of Clinical Assessments used for apraxia patients?
1) Limb Gesture
2) Limb Manipulation
3) Buccofacial Gesture
4) Buccofacial Manipulation
Give an example of a Limb Gesture
Wave goodbye
Give an example of a Limb Manipulation
Open a door with a key
Give an example of a Buccofacial Gesture
Stick out toungue
Give an example of a Buccofacial Manipulation
blow a kiss
What is the grading of questions used in a clinical assesment for an apraxia patient?
pantomime -> imitation -> object use
Define Ideomotor/Ideational Apraxia
Clumsy; difficulty with the selection, sequencing, and spatial orientation of movements
- Often use body-parts as objects
Why do patients rarely complain of apraxic disturbances?
- Often paralyzed in right arm
- Attribute clumsiness to using nondominant hand
- Apraxia most severe when asked to pantomime a skilled act, and mildest when actually using the object
What did Geschwind think caused apraxia?
Geschwind invoked a language mechanism: Localized to LH
Describe the pathway that Geschwind proposed?
Right Hand
- Command goes from Wernicke’s to premotor to primary motor in LH
Left Hand
- Command must also pass through Wernicke’s to pre-motor in LH, then to premotor in RH
Geshwind’s Patient #1
What part of his brain was damaged?
Describe his behavior
Damage
- The anterior fourth fifths of corpus collosum
Behaviour
- Would carry out command with right arm correctly
- When given commands to use left arm, would make no or incorrect response
- Could imitate or use actual object with left arm
In terms of Geschwinds pathway, what function was impaired in patient #1?
Patient #1
- Verbal information could not reach RH to control left hand
Why could patient #1 imitate?
He could perform those functions because they were not dependent on language
Patient #2 had damage in his left premotor region
Describe his impairments
- Paralysis of right limbs
- Failure to carry out commands in left limbs
Patient #3 had damage in the pathway between wernickes and premotor area in the left hemisphere
Describe his impairments
- No paralysis in either arm
- Apraxic in left and right arms
language can not get to the premotor area in both hemispheres
List reasons that disprove Geshwinds pathway
1) Other studies have not found a close relationship between aphasia apraxia
2) Unlike Geschwind’s patient, most apraxia patients are impaired on imitation
Describe why apraxic patients being impaired in imitation might disprove Geshwinds pathway?
If apraxia is due to disconnection of language areas, then these patients should be able to imitate - but they can not
what did Liepman & Mass propose?
1) Left hemisphere is not only dominant for language
2) Left hemisphere contains motor engrams
Why is left hemisphere dominant for
- Superiority of right hand is not just in greater strength, but greater skill
Describe motor engrams?
- “movement formulas”
- “time-space-form picture” of movement
- skill of left hand is “borrowed” from the left hemisphere
What is the broad reasoning behind why most apraxic patients can’t imitate
A Callosal region accounts causes accounts for function of language and motor engrams
Describe the effects of a callosal lesion?
What does this account for
1) Disconnects language
2) Separates left hemisphere motor engrams from the motor areas of the right hemisphere
Accounts for finding that the left hand of patients with right hemiplegia is more clumsy than that of people who broke their right hand
Where is the motor engram of a left-handed person located?
On their right hemisphere
Where are motor engrams stored?
In the parietal lobe of dominant hemisphere
What causes ideomotor apraxia?
1) Damage to SMG/AG
2) Disconnection of SMG/AG from premotor areas
What impairments arise when A) SMG/AG is damaged
B) Disconnection of AMG/AG from premotor areas
A) Impaired at performing to command and imitation
B) Impaired at discriminating poorly-performed from well-performed acts AND Impaired at performing to command and imitation
What experiment did Heilman conduct to distinguish between
A) impairments caused by damage to the motor engrams
VS
B) damage to the pathway between motor engrams and the premotor cortex
Gesture comprehension test
- watched film of person performing pantomimed acts
a) well-executed
b) clumsily performed
What is skill?
In learning a skill, a performer must combine appropriate movements into bth the correct and serial order and correct temporal pattern within that order
what does skilled performance involve?
The ** refinement through** practice of the sequencing and timing of the movements underlying a task
What is skilled performacne relfected in?
1) More coordinated and rapid performance
2) Economy of effort and muscle groups used to perform the task
Whta are the 3 stages of Skill Acqusition?
Which phases are controlled and attentional? Which aare automatic?
1) Cognitive Phase
2) Associative Phase
3) Autonomous Phase
Cognitive and Associative Phases = Controlled and Attentional
Autonomus phase = Automatic
Describe the Cognitive Phase (2)
- Identify strategy to accomplish task
- Verbalize each part of task
Describe the Associative Phase (3)
- Component parts of skill tried out
- Set of action components assembled
- Knowledge of results/feedback
Describe the Autonomous Phase (3)
- Autonomization of component processes
- Reduction in attentional demands
- Loss of ability to verbalize describe task
What is the key to automatization?
Predictability
The development of skill iccurs between the transition of what phases?
Between Associative and Autonomous phases
Which of the stages of skill acquisition are associated with closed-loop control?
open loop?
Closed Loop
- Cognitive Phase
- Associative Phase
Open Loop
- Autonomous Phase
Describe the closed loop mode of control
- Reliant on feedback
- Lag time > Reaction Time
Ex. A tracking task, with an unpredictable visual stimulus (engaging in this move-feedback-move mode)
Describe the open loop mode of control
- Internal Predictive control
- Lag Time < Reaction Time
Ex. A tracking task, with a predicitable visual stimulus. The movement of the stimulus is in the shape of a triangle
What is the key to internal open-loop control
Motor Programs
Describe Motor Programs
1) Organize sequence in advance of execution
2) Not dependent on feedback from prior movement
- Sequence of actions that allow us to participate and engage without relying on feedback
What is an example of a simple motor program?
- triphasic EMG pattern in ballistic movements (ex. a throwing movement)
What are examples of complex motor programs?
- Golf swing
- Shifting car gear
- Written signature
Independent of muscle groups (writing name on paper vs. a whiteboard)
What are pieces of evidence for motor programs
1) Independence from sensory feedback
2) Preprogramming of responses
Skill learning involves the qcquisition of increasingly more accurate motor programs
- Allows you to engage in predictive, open-loop, and automatic behaviour
When is feedback most critical and why?
- Feedback is critical at teh begninng stages of skill acquisition
- Initial stage involves development of template of how skill is performed
- Feedback from movement is compared to template
What are movement templates and motor programs?
Distinct memory representationS
Describe Motor Program
- Memory representation that generates skilled movements
- Can only be aquired by doing
- Inaccessible to consiousness, non-verbalizable
Describe Motor Engram
- Memory representation that is used in early stages of skill acquisition and that is used to evaluate sensory feedback
- Can be aquired by doing and watching and listening
- Consciously accessible, verbalizable
Describe the Contention Scheduling Mechanism
(Horizontal Pathway on the SAS Model)
1) Potential schema compete with each other to determine activation levels
2) Selection takes place on basis of activation level alone
Describe the Supervisory Attentional System
(Vertical on the SAS Model)
- Attention has only biasing role in motor program selection
- Action will be initiated if trigger conditions are well met, despite one’s desire to select another action
Example: Saying the color of a text even if the text is a word for a color
- When you are on “auto-pilot”, take the road home even though you are going to another place
What is a notabl part of the brain and motor circuit?
The striatum
What is the function of the striatum?
Striatum involved in motor programing
- Contention scheduling
- Cells respond to direction, amplitude, force of movement
Given the striatum’s role in the motor circuit, what would damage to this area result in?
- Instensive impairment in the ability to display motor programing and develop motor skills
What is Huntington’s Disease?
1) Inherited neurodegenerative disorder
- Autosomal dominant
- Onset 35-55 years
2) Profound loss of cells in neostriatum (80-90%)
3) Choreiform movements (writhing, dance like movements)
4) Progressive dementia
Disrupted Motor Programming
Describe a Huntingtons patient’s performance in tracking a predictable stimulus
What does this tell us?
- Improved over first few blocks by using early attentional (error-correction) strategy
- Impaired at developing more effective predictive mode of performance
Hungtinton’s is associated with impaired motor programming
Describe the Parkinson’s in terms of the motor circuuit pathway
- Damage in pathway that provides dopamenergic input to the basal ganglia
- Impaired modulatory input to the striatum
What is Parkinson’s Disease?
1) Neurodegenerative disorder
2) Loss of pigmented cells in substantia nigra
3) Classic motor triad
4) Impaired activation of motor programs
Define the Classic Motor Triad
1) Resting tremor
2) Rigidity
3) Bradykinesia (slowless of movement)
Describe Parkinson’s patient in terms of the motor programming
1) Intact motor programming per se
2) Impaired activation of intact motor programs
Describe how Parkinson’s patients have intact motor programming per se
- Normal tracking performance
- Normal pre-programming of movement sequence
- Kinesia paradoxia can perform complex movements easilty with extremeley salient stimulus
Describe how Parkinson’s patients have impaired activation of intact motor programs (modulatory input)
- Bradykinesia
- Increased attention or “will” to activate shemas
More conflicts not resolved
- interference between programs
- increased difficulty doing two tasks at once
What stage are motor engrams involved in?
- Accessibile to consciousness
- Recall explicit traces of how that act is performed (e.g., visual template)
- Motor programs are not accessible to consciousness (triggered automatically)
Describe Apraxia Disorder of “Quasi-Skilled Movement”
1) Disruption of motor engrams associated with controlled system used during the early stages
2) Sparing of motor programs associated with automatic system underlying skilled behaviour
How is apraxia assessed?
what does this indicate?
Apraxia is assessed very artificially
Some improve with imitation; almost all improve with the actual object
Often perform the skill normally in proper context!!!
when asked “show me how you bow” causes patient to consiously think of the engram
Describe how context informs motor programs
As context more closley matches trigger conditions, it is more likley that motor program can beactivated via the automatic (open-loop) system
Describe Early Stage Skill Learning in Apraxia
Impaired performance on early stage of skill learning in tracking task.
Apraxic patients can’t get past early phase to aquire new skills
Huntington patients were able to learn through the first blocks, then began to show impairments
