Impaired cognition Flashcards
What are some syndromes/disorders that involve an impairment of memory?
Amnesia
Korsakoff’s syndrome
What is amnesia?
When registration/storage processes are impaired by a disease/injury/stroke/alcohol
What types of amnesia are there?
Retrograde amnesia
Anterograde amnesia
Which type of amnesia is associated with an inability to form new memories after the injury/disease?
Anterograde amnesia
What is retrograde amnesia?
A loss of memory about events that occurred before the injury/disease
Which area of the brain is retrograde amnesia associated with?
Diencephalic lesions in the mammillary bodies/thalamus
Which area of the brain is anterograde amnesia associated with?
Hippocampal damage
What type of amnesia did Patient HM have?
Anterograde amnesia (had hippocampus removed to cue epilepsy)
What are the symptoms of Korsakoff’s syndrome?
- memory impairment (retrograde & anterograde)
- confusion (confabulation)
- disordered eye & limb movements
- learning deficits
What are some causes/biomarkers of Korsakoff’s syndrome?
- thiamine deficiency
- haemorrhagic lesions in mammillary bodies & other structures of the limbic system
- enlarged ventricles
- damage in the thalamus & other diencephalic structures (Jernigan et al., 1991)
What effect does a thiamine deficiency have on the brain?
Absorption of thiamine is impaired by malnutrition/alcohol
Brain regions dependent on thiamine suffer from impaired neuronal function
What is the primary source of recent-memory impairment in patients with Korsakoff’s?
Neuronal loss in the medial anterior thalamic nuclei
Which area of the brain is involved in the formation of episodic memories?
Thalamus
What disorder is an impairment of attention?
Hemispatial neglect
What do patients with hemispatial neglect do?
Don’t respond to stimuli on the contralateral side
Can’t disengage from items on the ipsilesional side (orientation bias)
What is hemispatial neglect NOT?
Not a visual deficit/hemianopia (= blindness over half of the visual field)
Which side of the brain is most often affected in hemispatial neglect?
Right hemisphere (principle in modulating attention) –> ignore the left side of the visual field
What are the symptoms of hemispatial neglect?
- deficits in body representation
- don’t incorporate the part of their world that they don’t perceive
- anosognosia (= unaware of their disorder)
- representational neglect
Behrmann et al. (1994) analysed eye movements in neglect patients. What did they find neglect patients did that healthy controls didn’t?
- made fewer fixations
- shorter inspection time on the contralesional left side
- started their search on the right side of the midline
- made more & longer fixations to the ipsilesional side
- more omissions of targets
What tests can we use to detect hemispatial neglect?
- Line bisection - bisect a horizontal line (estimate the centre)
- Clock-drawing test
How do neglect patients perform on the line bisection test?
They usually estimate the centre further away from the side that is neglected (more towards the right)
What skills does the clock-drawing test require?
Verbal understanding, memory, spatially-coded knowledge & construction skills
What methods can we use to treat hemispatial neglect?
Cognitive training Scanning training Repeated neck muscle vibrations Mental imagery training Video feedback training Prism adaptation
What is the process of prism adaptation treatment?
- The patient points at visual targets whilst wearing goggles. The initial points are off-target because their visual field is shifted in one direction.
- The ‘direct effect of prism adaptation’ occurs - the patient detects that they are making pointing errors and makes a conscious effort to try to fix the error via strategic recalibration.
- The goggles are removed; the direct effect adaptation observed as a result of prism exposure persists & results in the ‘prism adaptation negative after-effect’ - causes initial attempts in pointing to the visual target during the post-test to be in the direction opposite to the visual shift
