Visual extinction in relation to visuospatial neglect after right-hemispheric stroke: quantitative assessment and statistical lesion-symptom mapping

Abstract

Background Visual neglect and extinction are two common neurological syndromes in patients with righthemispheric brain damage. Whether and how these two syndromes are associated or share common neural substrates is still a matter of debate. Methods To address these issues, the authors investigated 56 patients with right-hemispheric stroke with a novel diagnostic test to detect extinction and neglect. In this computerised task, subjects had to respond to target stimuli in uni-and bilateral stimulation conditions with detection probabilities being assessed. A cluster-analytical approach identified 18 patients with neglect and 13 patients with extinction. Statistical lesion-symptom mapping analyses with measures for extinction and neglect were performed. Results Extinction and neglect co-occurred in a subset of patients but were also observed independently from each other, thereby constituting a double dissociation. Lesions within the right inferior parietal cortex were significantly associated with the severity of visual extinction. Visuospatial neglect was related to damage of fronto-parietal brain regions, with parieto-occipital areas affecting line bisection and dorsal fronto-parietal areas affecting cancellation task performance, respectively. Conclusion Quantifying lesion-induced symptoms with this novel paradigm shows that extinction and neglect are dissociable syndromes in patients with righthemispheric stroke. Furthermore, extinction and neglect can be related to differential neural substrates, with extinction being related to focal brain damage within the right inferior parietal cortex.

The hybrid model of attentional control: New insights into hemispheric asymmetries inferred from TMS research

“…The unilateral condition probes target detection in the absence of competition and potential effects are therefore conceptually closer to spatial neglect. Even though visual extinction and spatial neglect are dissociable in clinical populations, there is a large co-occurrence of the two syndromes (Vossel et al, 2011). In fact, there is hardly any evidence that TMS can induce clear-cut cases of extinction, that is, disruption of bilateral but intact unilateral stimulus detection, in healthy volunteers.…”

Apraxia and spatial inattention dissociate in left hemisphere stroke

“…To comprehensively assess (spatial) inattention, it is important to use multiple attention tests (Saj, Verdon, Vocat, & Vuilleumier, 2012;Verdon, Schwartz, Lovblad, Hauert, & Vuilleumier, 2010). Therefore, we used the line bisection test that is supposed to be sensitive to posterior lesions (at least for contralesional inattention: (Rorden, FuhrmannBerger, & Karnath, 2006;Weiss et al, 2000) as well as cancellation tests that are also affected by frontal lesions (Vossel et al, 2011). To further increase the sensitivity of our neuropsychological assessment (especially for ipsilesional and non-lateralized attention deficits), only cancellation tests with distractors were used in the current test battery (Weintraub & Mesulam, 1988).…”

Computing an Average When Part of the Population Is Not Perceived

“…Recent studies found a double dissociation between neglect and extinction, suggesting that these two conditions may reflect separate dysfunctions (Umarova et al, 2011;Vossel et al, 2011;Pavlovskaya, Soroker, & Bonneh, 2007;Bonneh, Pavlovskaya, Ring, & Soroker, 2004;Karnath, Himmelbach, & Küker, 2003; for a review, see de Haan, Karnath, & Driver, 2012).…”