final exam essay points Flashcards
Briefly what are the motor control theories of the absence of immediate bodily experience of movement failure?
- Dysfunction of the predicted state and actual state comparator
- Lack of motor intention compilation process
- No actual state signal despite intact predictor signal
- Proprioceptive loss accompanied by severe unilateral neglect
Describe the dysfunction of the predicted state and actual state comparator theory for motor impairment anosognosia
The brain is normally able to send a signal to alert a disconnect between actual state of movement and predicted movement within the motor control system through a comparator mechanism. If there is an impairment to that comparator in the motor system as a result of brain damage, the individual may not receive the signal to indicate motor failure
Describe the lack of motor intention compilation process theory of motor impairment anosognosia
If the brain damage that caused the paralysis extended to the motor system, then there could be an impairment in production of motor intention. No motor intention is actually compiled, meaning there is also no prediction of movement. Without this process occurring, there is no experience of trying and failing
Describe the no actual state signal/intact predictor signal theory of motor impairment anosognosia
A motor intention program is compiled and the predictor mechanism predicts a successful movement. However, there is no proprioceptive signal from the actual state of movement meaning that the comparator mechanisms cannot compare the two and only receives the predicted state.
What are the three reasons patients who do not have immediate bodily experience of movement failure might not be able to update knowledge of motor impairment?
- Unable to remember the evidence
- Unable to recognise that the evidence calls for evaluation of current beliefs
- Unable to carry out the task of belief evaluation
What are the tests that indicate that delusional beliefs about motor movement are not being updated or rejected?
Riddle Task: patient instructed to guess a word based five increasingly obvious clues. Patients with anosognosia performed worse than controls and non-anosognosics despite rating themselves as more confident. Indicates a problem in conceptualisation of hypotheses and error detection (experience of doubt).
D-KEFS: other researchers concluded that the riddle task is conceptually the same as the D-KEFS task, which is test battery to assess executive functioning where the main task is to discover the meaning of mystery words based on clues given in sentences
Wisconsin Card Sorting (WCST): battery that tests set-shifting, working memory, error detection and feedback utilisation. Patients with anosognosia achieved zero categories and had a 68% perseverative rate, indicating they are not taking in evidence to update their beliefs
Describe the shift in clinical neuropsychology to identify dementia diseases at asymptomatic stages
The detection of types of dementia is only effective if there is a significant gap before diagnosis for intervention. Levels of amyloid plaque and tau tangles proteins within the brain have been used as biomarkers to indicate risk of progression to AD. However, many people with these markers do not go on to develop the disease. Further, 40% of the risk factors for dementia are potentially modifiable, which calls for potential interventions to be made on both an individual and public policy level. Addressing lifestyle factors in all stages of life may prevent or delay the onset of dementia disorders in the population, as well as improve care for individuals post diagnosis.
Newer methods of earlier detection involve spatial navigation tasks (over episodic memory tasks) as brain regions that support spatial navigation are effected earlier in disease progression.
What are the risk factors throughout the life-span that can predispose an individual for dementia diseases?
A number of risk factors can predispose an individual to dementia well before its clinical onset:
Early life: less education (< 45 years)
Mid-life: hypertension, hearing loss, TBI, obesity, excessive alcohol
Later life: smoking, depression, air pollution, diabetes
Describe the three stages of clinical Alzheimer’s before diagnosis
It takes 15-20 years from the point of changes beginning in the brain to the onset of impairment of the abilities to think and function. This significant gap indicates the there is a potential to intervene.
Pre-clinical AD: neuronal and metabolic changes; reduced connectivity
Prodromal AD: increased neuronal loss, particularly in the hippocampal region
Early AD: additional neuronal changes in key brain areas
How would a life-course approach influence care of individuals who already have dementia?
For those with dementia, leading dementia research emphasises holistic and individualised care. Carpentier et al. (2008) define four factors for dementia care:
1. Family history -> ability to cope, past experience, support systems
2. Linked lives: everyone is interrelated and influenced by social and individual experiences -> family dynamics
3. Human agency -> freedom to act, make choice, autonomy
4. Organisational factors -> community level, institutional practices/policies
Describe the bedside tests in clinical neuropsychology and why they are helpful/limited
Bedside cognitive screening tasks are used in clinical/research neuropsychology to assess the presence and severity of a cognitive impairment. These tests have the advantage of easy interpretability, lack of pressure or distress for the patient and quick/easy administration
However, these test do not provide the breadth and depth required for further neuropsychological assessment. They are purely starting points that allow the neuropsychologist to develop hypotheses and narrow the field of potential diagnoses
What are the relevant bedside tests (with examples)?
- Tests of everyday attention: battery that assess concentration through simulation of everyday tasks ->ecologically viable.
4 subtypes:
- Visual selective attention/speed: map search
- Sustained attention: elevator counting
- Auditory Verbal Working memory: elevator task with distraction
- Attentional Switching: visual elevator - Visual Object and Space Perception:
- incomplete letters, silhouettes, progressive silhouettes - WM Index: tests an individual’s ability to take in/hold info and perform mental operation or manipulate that info
- Digit span backwards, Corsi block tapping backwards - Memory and Learning
- Doors and people
Describe the use of brain imaging tools in neuropsychology
Braining imaging tools and methodological advancements in computational modelling of the brain have extensively benefited neuropsychological assessment. The generation of functional maps of brain activity based on changes in cerebral metabolism, blood flow or electrical activity are now commonplace tools for assessment. One such neural imaging tool is MRI.
Describe MRI procedures
Conventional MRI machines measure structural and physiological abnormalities by acquiring slices of the brain and combining them into a 3D image. MRI can differentiate between grey matter, white matter and cerebrospinal fluid. Imaging is increasingly being used to aid in diagnosis of neuropsychological conditions. This paradigms allows for real-time detection and localisation of brain injuries such as stroke, infarctions, tumours, as well as cerebral dysfunction.
Describe dMRI
MRI can be manipulated on different levels to investigate specific areas or mechanisms of interest. One of these methods is diffusional MRI, which is an added contrast that measure the diffusion of water molecules within the brain from a number of different directions. This type of contrast provides insight into the microscopic details of tissue within the brain, including obstacles to connectivity and anisotropy
Describe T1-weighted and T2-weighted MRI scans
Varying factors such as magnetic pulse repetition time (TR) and echo time (TE) produces different kinds of image. T1 and T2-weights are the most common variables added to MRI scan procedures. T1-weighted scans have a shorter TE and TR, whereas T2-weighted scans have a longer TR and TE.
