1. Unilateral neglect major theoretical accounts

2. What could go wrong after RH damage explaining the contralesional neglect?
Attentional disorders
Spatial representation disorders
Pre-motor representation disorders

3. Attention theories: Heilman
Reduced arousal of right hemisphere
Asymmetry of attention control
Attention to the left side of space is provided exclusively by the right hemisphere whereas Attention to the right side of space is provided by both hemispheres.

4. Asymmetric Attention Control

5. Attention Control in Neglect

6. Attention theories: Kinsborne
Hemispheric rivalry predicts:
Gradients rather then hemifield effects
‘Hyperattention’ on the right (‘magnetism’)
Extinction in the ipsi-lesional side

7. Unilateral Neglect

8. “Starry Night” test

9. Reaction Time - neglect patients
110 6 -3 -2 -1 | 1 2 3
0.5
1.5
2.5
RT/midline-RT 8
Deouell et al., 2000

10. Anderson (1996) Salience model
According to Anderson, the line is bisected where the saliency of the left and right sides are equal. After the lesion, the saliency map is distorted in a way that short lines actually have more saliency in their left side and are therefore bisected to the left of the midline.

11. Attention theories: Posner
Covert shifts of attention
Parietal - Disengage
Sup. Colliculus - Move
Thalamus - Engage

12. Controlling spatial attention beam: Posner
Disengage
TPJ
Superior Colliculus
Move
Pulvinar
Engage

13. Posner’s cueing paradigm* *

14. Posner’s paradigm - valid cue
Fixation
Valid cue *
Target

15. Posner’s paradigm - invalid cue
Fixation
Invalid cue *
Target

16. 07.42
7.42 Fig. 2, Posner et al., “Effects of parietal injury on covert orienting of attention,” The Journal of Neuroscience 4: 1863–1874, (1984). Adapted with permission of The Society for Neuroscience.

17. 07.09
Cost
Benefit
Posner, M.I., Snyder, C.R.R., and Davidson, J., Attention and the detection of signals, Journal of Experimental Psychology: General 109 (1980): 160–174. Copyright © 1980 by the American Psychological Association. Adapted with permission.

18. Attentional systems (Posner)
Anterior Att. System (Target Detection)
Posterior Attentional System (Orienting)
Vigilance/Alerting System

19. New formulation (Corbetta)
Stimulus + Response Selection
Alerting, Sensory Reorienting
Cingulate – Response monitoring, not selection …

20. Functions of parietal lobes
Dror – Breakdown of connectivity
Adi – IPL and attention theories of neglect
Ronen – The role of the parietal lobes in timing events.

21. Representational Theories
Bisiach - Neglect is a disorder of space representation
Neglect is demonstrated in imagery (Piazza effect)
If attention is shifted, it is shifted over an internal representation of space (rather than space itself)
Damage to circuits representing segments of space precludes action towards these segments

22. Representational Theories
Piazza del Duomo effect

23. Piazza del Duomo effect

25. הזנחת צד - ייצוג מנטלי

26. Is the number larger than…
Increase in RT just to the left of the target number
Vuilleumier et al., 2004

27. Gradient of Neglect and Parietal Neurons
Pouget and Driver 2000

28. Reaction Time Accuracy RHS LHS Control Deouell et al., 2005 Top Bottom
1000
100%
600
80%
Top
Bottom
LEFT
Right
LHS
600
100%
500
80%
Control
450
100%
400
80%
1000
100
Control
RHS 96
LHS
RT (msec)
800
Hits (percent) 92
600
LHS 88
Control
RHS
400 84 -3 -2 -1 | 1 2 3 -3 -2 -1 | 1 2 3
Deouell et al., 2005

29. Subtypes of neglect?
Buxbaum et al., 2004

30. Role of non-spatial effects
TOJ task:
Figure 1 The sequence of events for a single trial, with time running from bottom left to top right. The trial began with the patient fixating the central cross for 600 ms. After a delay, a salient tone of unpredictable pitch sounded in warned trials (as indicated by the musical notation, which was not presented visually, in the second frame); there was silence in the intermingled, and more common, unwarned trials. After a variable, random delay, a visual bar appeared on one side (left in the figure), followed by a bar on the other side at a variable SOA. Both bars then remained until the patient judged verbally whether the left or the right bar had appeared first. In the main experiment, the occasional alerting sounds were always central. In the follow-up study, they were always to the far right of the visual screen.
Robertson et al., 1998, Nature

31. Staircase procedure from one subject
Staircase procedure from one subject. W/o the warning, the reversals (=judgment of simultaneity) start with a significant left lead. When warned, the reversals occur more around 0 (as normal).
Robertson et al., 1998