Week 4: Remembering and forgetting, examples of critical sense in clinical practice. Flashcards
2x2 issue with double dissociations - what does this assume?
Assumes the system has only 2 working componants
Other types of neglect that have been reported (other than visual /// perceptual neglect)? There are 4 types
- near vs far space neglect
- personal vs near space neglect
- implicit vs explicit neglect (not aware of deficit vs aware of defecit)
- object-based (half of object attended to) vs space based neglect
(Marshall and Halligan, 1988) - demonstration of implicit vs explicit neglect
- subject has implicit visuo-spatial neglect
- when shown 2 pictures of a house either side of each other, one of houses on fire
- asked if 2 houses are different - they reply no
- but when asked which of the houses they would rather live in, they pick the house that is not on fire (implied awareness that house is on fire)
Features of PERSONAL neglect
- More common with lesion to RHS
- hemispheric asymmetry with regards to directing proprioception
- LHS is more used for EGOCENTRIC ATTENTION (eg evaluating the strength of a tactile stimulus
- neglect associated with many cortical and subcortical lesion sites
- double dissociation with EXTRAPERSONAL neglect seen –> the two are underpinned by different anatomical or functional modules
What does hemispheric asymmetry with regards to directing proprioception mean
RHS of the brain has a more significant role than the left in directing and encoding spatial information surrounding objects relative to other objects (in the case of personal neglect, the limb)
Why may personal neglect go beyond attention and include defecits of body representation?
Somatosensation is a highly integrated cognitive and proprioceptive system
What sub cortical/subcortical structures have personal neglect been associated with?
Thalamus
Internal capsule
Basal ganglia
What is Anosognosia?
Unawareness of having a motor or cognitive impairment
Causes, common symptoms and problems with diagnosis of Anosognosia?
Common anasognosia is visuospatial neglect
Causes: lesions or damage to the R hemisphere, aspects of personality (Weinstein & Kahn, 1955), specific cognitive damage
Diagnostic issue: L brain anosognosia = underdiagnosed!
‘Assessing Anosognosia: a critical review’ (Cocchini, Beschin, Della Sala, 2010) - 3 types of assessing Anosongnosia?
Strucutred interviews –> assess patient awareness of their own defecits
Self rated questionnaires –> ask patients about their ability to carry out tasks and level of self awareness
VATAm (Della Sala, 2009) –> a visual analogue test which demonstrates certain tasks with pictures
‘Assessing Anosognosia: a critical review’ (Cocchini, Beschin, Della Sala, 2010) - problems with assessing Anosognosia?
2 of The methods rely too much on verbal competency People with language or reading defecits may not be diagnosed Unreliable methods (hence VATAm was developed)
(Cocchini et al., 2009) inflated RHS diagnosis of Anosognosia –> outline study
Used structured interview on 1 group of patients and VATAm on 1 group of patients, both groups with lesions to the LHS of the brain.
Using the VATAm, 40% of patients with LH lesions diagnosed with Anosognosia. only 10% with structured interview
(Cocchini et al., 2009) inflated RHS diagnosis of Anosognosia –> conclusions and implications of study
VATAm = 60% more reliable method of diagnosis
Lower diagnosis of LHS could be due to multi-faceted nature of Anosognosia –> RHS and LHS play different roles, but LHS does process awareness of defecits too
(Beschin et al., 2012) Neglect and Anosognosia –> dissociation of treatment effects – OUTLINE STUDY
5 patients with both neglect and Anosognosia (both have been demonstrated separately in the past).
Test patients with TECHNIQUES found to alleviate Anosognosia
What 3 techniques have been found to alleviate Anosognosia?
Optokinetic stimulation
Prismatic shift of the visual field
Transcutaneous nerve stimulation