neglect

Question 1

background

Answer 1

• ” A failure to report, respond or orient to novel or meaningful contralesional stimuli” - Heilman et al, 1985.
  
  • Patients may often:
  • Shave/make up only one side of their face
  • Eat off one side of plate
  • Read text on one half of the page
  • Bump into walls/ignore people on their left
• Be unaware of their difficulties “anosognosia”

Question 2

causes

Answer 2

· The most common cause of neglect is a stroke affecting the right-side of the brain.
- The area most associated with neglect in 20 patients - the parietal lobe on the right.

Question 3

line bisection

Answer 3

· Mark the midpoint of a line
- They’ve marked nearer to the right side of the line, and missed some of the left side lines.

Question 4

cancellation tasks

Answer 4

· Most sensitive - a lot of information to process
- Made harder by using a more “crowded” array

Question 5

is neglect just a problem with vision/visual perception?

Answer 5

· If it is, then a patient who is blind on one side will act in the same way.
- The next patient had a stroke that damaged visual areas on the right side of her brain.

Question 6

visual problems do not explain neglect

Answer 6

• They have difficulty seeing it but they know the left side of the face is there, so they move their face.

Question 7

recovery from neglect

Answer 7

Neglect usually recovers spontaneously within a few weeks/months.

Question 8

what frames of references does neglect operate on

Answer 8

· Examples so far have been in an egocentric reference frame (things to the left of oneself).
· Neglect also operates in “object-centred” reference frames.
- This tells us something about how objects are processed in the absence of awareness.

Question 9

object-centred neglect

Answer 9

· Many objects have an intrinsic axis - arrow or house
· Neglect patients appear to extract this dominant axis and neglect what is on the left of it - even if it is not on their “egocentric” left.
- This is regardless of how the picture is laid.

Question 10

task

Answer 10

· Patients had to respond to the presence of a gap in the central triangle.
· The gap was always in the centre of fixation.
· Examples D and F were harder for patients with neglect - they are on the left side of the axis.
- They subconsciously know its there so they know to neglect it.

Question 11

“blind-side” in neglect

Answer 11

· Task:
· Are the houses the same or different?
· Which house would you prefer to live in?
· Suggests unconscious processing can influence action/decision making.
- Consciously it can still affect bias in the decision.

Question 12

does neglect affect mental representations

Answer 12

Often assessed by asking patients to draw things from memory (e.g., a clock or a flower).

Question 13

neglect for visual imagery

Answer 13

· Bisach’s “Milan Square” experiment.
· Asked people to imagine it facing in one direction or the other.
- People would report more of the buildings on the right depending on which way they were facing.

Question 14

extinction

Answer 14

Only occurs when two or more objects are presented at the same time.

Question 15

rees et al 2000

Answer 15

· Patient correctly reported 58/60 stimuli presented in left visual field when these were presented alone.
- But only identified 2/60 when presented along with a stimulus in right visual field.

Question 16

non-spatial deficits in attention

Answer 16

· Neglect patients often have poor working memory (e.g., touchscreen cancellation).
· Show a larger and longer “attentional blink”.
- Also have problems with sustained attention.

Question 17

summary

Answer 17

· Neglect - inattention to (usually) left side of space.
· Usually caused by stroke affecting right parietal lobe.
· Test used to assess neglect - cancellation tasks, line bisection tasks, copying/drawing tasks.
· What neglect tells us about visual processing and attention:
1. It operates in multiple spatial and object reference frames.
2. High degree of processing occur in absence of awareness.
3. Visual imagery is processed similarly to incoming sensory information.
- Extinction - a milder form of neglect only revealed when stimuli “compete” for attention.