Week 7 Corbetta and Shulman (2011)

why is neglect unusual among lesion syndromes

severity is modulated within seconds by behaviour

recovery timeline of overt spatial symptoms

days to weeks for major improvements, smaller deficits persist

Unilateral spatial neglect definition

failure to attend/respond to contralateral stimuli

saliency meaning

sensory distinctiveness + behavioural relevance

spatial pattern about neglect even without stimulus

continuous ipsilesional gradient, gaze deviates rightward during search and at rest

evidence that ipsilesional items are focused on more

task irrelevant probes and relevant targets both attract more saccades to the ipsilesional side

egocentric vs allocentric prevalence

egocentric neglect more common, allocentric is rarer and dissociable anatomically

representational neglect

deficit in forming/manipulating left side mental images, almost always co-occurs with visual neglect

extra memory related issues that worsen neglect?

vertical VSTM deficits and trans saccadic remapping deficits (causes repeated refixations on the right)

why are line-bisection errors mostly rightward

Exploration failure of the left side + tonic oculomotor bias

best diagnostic test

Cued simple RT task

why do many lesions in right-hemi cause neglect

white matter disconnections and subcortical lesions disrupt a network not just one single node

neuromodulatory basis for right dominance

LC-norepinephrine input means stronger right-hemisphere arousal/reorienting/detection

pivot linking VAN and DAN

Inferior Frontal Junction (IFJ), connects both and lesions make strong spatial attention deficits

causal evidence for network imbalance

stimulating right fronto-parietal SLF (Superior Longitudinal Fasciculus) causes worse neglect and more rightward bias

framework of the disorder

right ventral damage leads to dorsal imbalance leads to rightward attention/eye movement bias and egocentric salience gradient