Neuroscience weeks 2-5

• Overt orienting


  Fixation which requires eye movement towards target
• Covert orienting


  Fixation on cross & not moving eyes towards target
• Posner Cueing tasks (Covert attention)


  1. Sometimes target is present, sometimes not

  2. Arrow points towards direction of target
• Endogenous Cue


  Central Cue, Voluntary Shift, top-down, goal directed
• Exogenous Cue


  Peripheral Cue, Automatic Shift, bottom-up, Stimulus driven
• Experiment: No 99, each participant did 360 trials
• Trial probabilities


  • Centre: 0.6
  • Left: 0.1
  • Right: 0.6
  • Catch: 0.2
• Left + right valid (valid) or invalid (invalid), 6 diff cue-target intervals, measures inhibition of return
• Spatial neglect


  An inability to report, respond or orient to stimuli presented on the side opposite a brain lesion not due to primary sensory or motor defects
• Experiment overlap condition


  1. O gap condition

  2. + 100 g gap condition
• La frabion cross + target on left side, cross disappings when target comes off
• The more interesting something is in the middle, the less likely people are to spot the targets
• Selective filtering


  Putting on headphones and playing different things in each ear
• Selective set experiments


  Flanker task, cueing, more constrained, brief visual display, small stimulus set, response from small no. of possibilities, reaction time
• If you get rid of stuff on the right side it's easier as the right side was distracting to patients with neglect
• Posner et al's (1984) 3 components of visual attention


  • Engage attention on target
  • Disengage attention from target
  • Shift attention to new target
• When 2 stimuli come up together in competition, patients tend to miss the one on left. Patients more likely to say right comes up before left even if left comes up way before right
• or invalid (unand), 6 diff cue-target intervals, measures inhibition
• Attention


  The taking possession by mind, in clear and vivid form, of one out of what seem several simultaneous possible object or trains of thought. It implies withdrawal from some things in order to deal effectively with others.
• Attention has: Limited Capacity, Competition → Something louder or more interesting will steal your attention, and bias
• When paper is turned around, left side becomes right. Patients can follow with fingers but if they look up they can't find it again
• A normal person might start crossing out on left corner and go across, but people with neglect start on right, it gets messy as time goes on
• Up to 80% strokes lead to spatial neglect
• Spatial neglect can affect parietal lobe
• Comes following damage of a range of areas
• 58% of stroke survivors regain independence
• 82% walk independently (with or without aid) -> most recovery in first 2 months, loss recovery at 4-5 months, little further recovery expected at 6 months
• Neglect leads to increased levels of disability, poorer outcome, longer stays in hospital, increased chance of needing long-term care
• Someone with neglect might have difficulty following obstacle courses - can't plan routes, make same mistakes each time, have trouble avoiding obstacles
• To test for neglect: Star Cancellation task - often only right side crossed out
• Copying tasks - devoid of left side in copy
• Judgements (line bisections) -> bisected 3/4 towards the right (lesion on right so can't see left side)
• Rehabbing wheelchair navigation in patients with neglect


  • The critically driven intervention shows promise and may be useful in training sessions
  • They limit normal top-down requirement of cueing approaches
  • Not for everybody - can't predict who will respond
• Motor neglect


  Favourable use of right hand, left hand not used
• Anosognosia


  • Woman ties undoing a belt as if left hand is holding it, but it isn't, so she can't open it
• Doorway accuracy test


  Go towards one side
• Caloric stimulation


  Can help them become more oriented to the left side
• Prism adaptation


  1. Practice moving hand from dot to dot when visual field shifted right, body recalibrates vision over time

  2. When visual field is reset, right side is missed because body still calibrated to left

  3. Crosses more targets on the right than before adaptation

  4. Person misses right side of target, adaptation occurs, person reaches further to the left
• Cognitive testing in real world


  Line bisections get smaller, Crossover effect, guessing occurs
• Normal situation with left neglect


  Right joystick operated with right hand