Apraxia Flashcards
What is Apraxia?
The loss of ability to execute or carry out skilled movement and gestures, despite having the physical ability and desire to perform them
Functional Equivalence Model (Jeannerod, 1994)
Overt and Covert (imagined) actions share common mechanisms and show functional equivalence
-Predicts that motor imagery and overt actions should activate largely overlapping areas of the brain and should closely match one another’s behavioural output e.g., timing
-Motor imagery and overt actions are functionally identical, differing only in terms of whether the body moves
PETTLEP model (Holmes & Collins’, 2001)
The PETTLEP model of imagery provides a framework for the effective execution of imagery interventions
-Used for motor imagery training and therapy
PETTLEP:
Physical
Environment
Task
Timing
Learning
Emotion
Perspective
Motor-Cognitive Model of Motor Imagery (Glover & Baran, 2017)
According to the MCM, motor imagery differs from overt action primarily through these of executive resources to monitor and elaborate a motor image during execution which can result in a lack of correspondence between motor imagery and its overt action
- Disagrees with the FEM model
- Motor representations are not the only source of information used to generate motor imagery
- In the Motor-Cognitive Model, motor representations provide only a framework for motor imagery
- Executive functions required to develop – into full motor image
What is Motor imagery?
A cognitive process in which a person imagines that he/she performs a movement without performing the movement
What are Executive functions in motor imagery?
Executive functions – use executive resources like those used in other types of conscious processes (e.g., working memory, inhibition, mental operations).
The amount of resources needed is related to the strength of the motor rep
- stronger rep- fewer executive resources needed
- weaker rep- more executive resources needed
Predictions of the Motor-Cognitive model
Behaviour: the correspondence between Motor Imagery and Overt Action should be lower when:
- actions are less practiced
- actions are more online
- executive functions are otherwise engaged
If the MCM is correct, then:
- when executive resources are otherwise engaged, motor imagery should be affected to a much greater extent than overt action
- the extent of these effects on motor imagery should depend on the extent to which executive resources are depleted (more engaged- larger effects on motor imagery)
Testing the MCM: behaviour
Findings
- motor imagery was much more affected than overt action
- when executive resources were otherwise engaged, motor imagery became much slower (overt action barely affected)
Conclusion
- suggests that executive functions are important for motor imagery e.g., there is not a “functional equivalence” between motor imagery and overt action
Implications for treatment/training
- mcm suggests treatment/training using motor imagery will work best for familiar actions
- actions should be learned first then practiced using motor imagery
- requires patient/performer be free of distraction
Laterality in PL (dominance of one side of the brain in controlling functions)
-parietal lobe is heavily lateralised
-likely because of the great number of higher functions that are processed here
-whereas, right PL is associated mainly with spatial functions, the left PL appears to encompass several non-related functions (e.g., language, emotion etc)
However, patterns of laterality are not ubiquitous
e.g., a right-hemisphere patient can have language deficits
Also, left-handed people tend to have functions that are less lateralised e.g., language in both hemispheres
Apraxia: damage to what lobe?
associated with damage to left IPL (Inferior parietal lobe), either PMC, or their interconnections
-can include damage to subcortical motor structures
What is Ideomotor apraxia (IMA)?
is the impaired ability to perform a skilled gesture with a limb upon verbal command/imitation
What is Ideational apraxia (IA)?
is the inability to correctly order or sequence a series of movement to achieve a goal
For example, patients with ideational apraxia cannot perceive the purpose of a previously learned complex task and therefore cannot execute the required movements in the correct sequence (They may put their shoes on before their socks)
Intransitive Gestures?
Patients often have difficulty in copying and/or producing gestures to command
Imitation
The clinician might say “do as I do” and e.g., touch their nose with their finger
Errors can be of two types:
Selection: patient does wrong movement entirely, but is accurate
Kinematic: correct movement is selected, but executed poorly
Movement Sequencing
In everyday life we must execute movements in the correct order
Patients often struggle with this
-e.g., in opening a can of tomatoes, might turn the can opener before placing it on the can
-can be studied experimentally using various tasks
Kimura Box Test (Sunderland & Sluman, 2000)
Pressing, pulling & pushing; performed individually, then in sequence (recording of accuracy and speed)
-patient shown the various possible movements, then asked to execute them in a particular order
Pantomime
Patient is asked to mimic a skilled movement such as the use of a tool
e.g., Poizner et al, 1989) Slicing bread study
patients generally poor at this, but got better with more cues
Made errors in kinematics of movement
Selection vs Execution errors
Selection errors- where an entirely wrong movement is chosen but executed well (ideational apraxia)
Execution errors- where the correct movement is chosen, but executed poorly (ideomotor apraxia)
Ideational vs. ideomotor apraxia (localisation)
Primary Motor Cortex (PMC) – ideational
Left Inferior parietal lobe (IPL) – ideomotor
(Liepmann, 1920): ideational/ideomotor distinction
Ideational apraxia
- it is the idea of the action that is disturbed
Ideomotor apraxia
- it is the execution that fails
LEFT IPL
Left IPL
Ideomotor apraxia (IMA) – is the impaired ability to perform a skilled gesture with a limb upon verbal command/imitation
Parietal lobe
- Involved with movement coordination and processing sensations
PMC
Ideational apraxia (IA) – is the inability to correctly order or sequence a series of movement to achieve a goal
For example, patients with ideational apraxia cannot perceive the purpose of a previously learned complex task and therefore cannot execute the required movements in the correct sequence (They may put their shoes on before their socks)
Alien Hand Syndrome
A phenomenon in which one hand is not under control of the mind
-The person loses control of the hand, and it acts as if it has a mind of its own
-Some people develop alien hand syndrome after a stroke, trauma, or a tumour
-Patient has one hand they cannot control
-Hand responds to whatever is in the environment
THEORY (Heilman and Rothi, 1993)
-Argued for a role of the left IPL in storing these motor programmes “visuokinesthetic engrams”
- When the left IPL is damaged, so are the programmes
- This leads to ideomotor apraxia
- When the IPL – connection PMC is damaged, similar results
Apraxia Rehabilitation
Focus here on training the upper limb apraxia
- Gesture training
- Strategy training
- Direct and explorative training
Gesture Training (Smania et al. (2006)
provided practice training for patients on three types of gestures:
- Transitive
- Intransitive meaningful
- Intransitive meaningless
Training involved moving patients from easiest to most difficult levels of gestures
E.g., for transitive gestures, might start with handing patient the physical object to use, then pictures showing object being used (e.g., spoon used to bring food to mouth) which patient had to imitate, then just presented picture of object
Gesture Training: transitive
Phase 1: hand a spoon to patient, ask to show its use in eating
Phase 2: show picture of spoon in use, must imitate
Phase 3: show picture of spoon, have patient demonstrate use
- Similar stepwise training on intransitive (meaningful and meaningless) gestures
- After training, patients showed significant Improvement on both transitive and intransitive gestures
- Some improvement also on gesture recognition, and on ADL (activities of daily life) questionnaire
- None of these benefits accrued to a control group who did not receive the therapy
Strategy Training
The aim here is not to improve the apraxia itself directly through practice, but to teach strategies that can be used to compensate. Depending on what part of task patient struggles with, therapists can provide guidance.
- e.g., if patient has difficulty initiating movement, therapist provides additional instructions
-e.g., if patient is poor at execution, therapist can help guide movement
Using a spoon:
If patient is slow to initiate, therapist might suggest verbally “bring the spoon to your mouth”
If patient executes poorly, therapist might suggest “try to move in a straight line between the bowl and your mouth”
This type of training improves ADL performance but not apraxia overall
Direct and Explorative Training
(Goldenberg & Hagmann, 1998)
based on idea that there is no “apraxia” per se, but a problem with recognizing the spatial relations among objects
Direct training:
-Direct training simply involves a therapist offering close oversight and guidance
-A very “hands-on” approach – i.e., the therapist intervenes (physically if necessary) if the patient is making an error
-Intervention only ceases when patient is performing action correctly
Explorative training:
-Explorative training: encourages patients to understand the function of objects by examining its form and structure
-The idea is to train patients to understand objects, then assumes their use will become clear and there will be no more “apraxia”
Conclusions:
Direct training is successful, but only for specific tasks trained on (does not generalise)
-E.g., direct training in spoon use would not improve use of a fork and knife
-Exploratory training was not successful
