Week 10 Apraxia Reading Flashcards
Describe the findings of the apraxia paper by Rumiati (2001)
2 x brain damaged patients with limb apraxia couldn’t execute tasks of daily living, whilst they could sequence photographs representing these same tasks. They could still recognise the objects involved (non visual agnosia), and they still knew about the objects (no loss of knowledge). 1 x control subject (brain damage w executive function deficits) could still perform actions, but had faulty sequencing of photographs of actions. She could still sequence stimuli other than actions (i.e. numbers and stimuli), and still displayed knowledge and could perform actions about the task. DOUBLE DISSOCIATION. THUS apraxia deficits NOT caused by degraded action sequence representations.
What is ideational apraxia?
deficits in performing everyday tasks not attributable to motor deficits.
What were some flaws in early studies of MOT to explain ideational apraxia?
Studies testing ‘amnesia of usage’ found object misuse and mislocations of actions, however, they did not measure visual recognition abilities, so could not rule that out as a cause.
Other studies showed deficits in performance of actions as well as sequencing errors of photographs, thus postulating errors due to deficits in sequential organisation of actions.. However, visual recognition far from perfect (65%), and no knowledge of objects was tested.
Frontal Apraxia posits that IA is due to deficits in top down processing and enhanced bottom up (contention scheduling) - stimulated by environment.
What was the concept of ‘amnesia of usage’?
deficits in accessing semantic repertoire - specifically those that have to do with the way an object must be used
What are some unresolved issues posited by Rumiati?
What is the relationship between semantics and carrying out actions? Semantics not necessary or sufficient for routine task performance - patients with poor semantic perform fine on single object tasks.
failure on MOT and action sequencing tasks have been allocated to both IA by some and to ADS by others.
Name the double dissociation between ideational apraxia and ideomotor apraxia
Ideational = deficit in using objects (MOT) sequencing photograph ability fine Idemotor = mimicry
Name the INTACT abilities of IA patients
Accurate identification of objects, accurate matching of objects to function, accurate identification of objects when given its function, accurate recognition of actions depicted in sequence of photographs. THUS, defective performances on MOT IS NOT dependent on a lack of knowledge for object functions.
Accurate sequencing of functions is intact, thus performance is not limited by deficits in sequential organisation.
When are inappropriate object representation most common?
During schema selection occurs at the lowest level of the hierarchy
Name some error types typical of a parameter in which the activation of higher-level schemas would not be at their greatest
Step omissions, action anticipations, subtask omissions, perseveration, object substitutions, action additions
Is knowledge that subserves recognition and execution of actions involving objects the one concept?
No - IA subjects can recognise pantomimes and own mistakes when reproduced by the experimenter, but cannot correctly perform actions. Concludes that contention scheduling system does not need to be called upon when recognition of actions needs to be recognised.
Explain the notion of contention scheduling
It is the mechanism by which simple routine actions can be produced without conflicts occurring in the performance of tasks - accomplished by activation and inhibition of schemas at the appropriate times. Triggers of activation and inhibition can be environmental.
