L6- Stroke & Action

Question 1

What is a stroke?

Answer 1

Cerebrovascular accident - no blood flow or ruptured vasculature resulting in the death of neurons

Question 2

Describe the blood flow in the brain

Answer 2

Provided by internal carotid arteries & vertebrobasilar system
-Meet at Circle of Willis - Provides redundancy (systems can supply other region if one cant

Question 3

What are the 2 main types of stroke?

Answer 3

Ischaemic - blockage by clot or plaque (87%)
Bleeding in the brain- intracerebral haemorrhage (10%) and suborachnoid haemorrhage (3%)

Question 4

Outline stroke statistics

Answer 4

-7.08mil globally each year
~8% die
-57% return to work within a year, 66.7% within 2

Question 5

What are the stages of stroke recovery

Answer 5

Acute - 1st week
Subacute- 1 week - 3 months
Post acute - 6-12 months
Chronic - > 1 year

Question 6

What is hemianopia?

Answer 6

Cannot see 1/2 of space

Question 7

What are the visual pathways for the LVF? (& RVF)

Answer 7

LVF projects onto the right of the retina, & right dorsal lateral geniculate nucleus, via the optic chiasm, and then the right hemisphere.
-Opposite for RVF
-Within visual fields, there are monocular portions (left/right only) and binocular ares (overlap)

Question 8

What experimental evidence is there for the visual pathways?

Answer 8

-Deoxyglucose staining in macaques (VF projections stained contralateral hemisphere)
-Human cytochrome oxidase staining

Question 9

What are the effects of poschiasmatic lesions?

Answer 9

-Stoke damage affects visual pathway after optic chiasm
-results in loss in part of either visual field
-loss for BOTH eyes in SAME visual space

Question 10

How does hemianopia affect behaviour (Warren, 2009)?

Answer 10

-Affects reading and collisions more than other behaviours
-Negatively impacts drawing, shopping, & financial management a lot

Question 11

Outline the findings of Zihl (1994; 1999; 2009)

Answer 11

1994:
-visual search task
-2 homonymous hemianopia (HH) patients searching more and frantically than controls
1999:
-11% reporting no difficulty had abnormal scanning behaviour (74% for those reporting difficulty)
2009:
-Line bisection
-Right HH deviate to the right, & vice versa
-Similar deficit regardless of how much VF lost
-Errors unrelated to primary visual lesions, likely more related to widespread brain damage from stroke

Question 12

Outline Smith et al. (2015)

Answer 12

-Visual search task
-Divided ppts by performance (adequate vs inadequate compensating)
Reaction time test:
-HH ppts good except those with affected peripheral vision & inadequately compensating
Directional judgement task:
-generally slower but more accurate than control
-Inadequate slightly worse
Driving sim task:
-Inadequate group mych worse in affected condition (slower & less accurate)

Question 13

Can people with HH compensate, and how?

Answer 13

They can, likely relying on spatial memory and changes to eye movement
-Those who can’t likely have more extensive strokes, affecting other areas
-Both subsets have deficits though (e.g. collisions)
-HH is deficit primarily of vision, not sense of space

Question 14

What is hemispatial neglect?

Answer 14

-Deficit in attending to/acting in hemispace contralateral to brain damage
-No awareness of this side of space, or even own deficit sometimes
-Attentional bias to other side
-Capable of detecting stimuli on affected side

Question 15

Is hemispatial neglect a disorder of attention or perception?

Answer 15

Attention
-Milan square study