Neural Correlates of Modality-specific Spatial Extinction

Abstract

Sites of lesions responsible for visual, tactile, and/or motor extinction have not been clearly identified. We sought to determine the frequency of extinction in various modalities immediately after acute ischemic stroke, the rate of co-occurrence of extinction across modalities, and areas of infarct and/or hypoperfusion associated with each modality of extinction. A total of 148 patients with right supratentorial stroke were studied. In Study 1, 88 patients without hemiplegia, hemianesthesia, or visual field cuts were tested within 24 hours of onset for visual, tactile, and motor extinction, and underwent magnetic resonance diffusion and perfusion imaging. Associations between modality of extinction and areas of neural dysfunction (hypoperfusion/infarct) were identified. Of the 88 patients, 19 had only tactile extinction, 8 had only visual extinction, 12 had only motor extinction, 14 had extinction in two or more modalities, and 35 had no extinction. Tactile extinction was associated with neural dysfunction in the inferior parietal lobule; visual extinction was associated with dysfunction in the visual association cortex; and motor extinction was associated with neural dysfunction in the superior temporal gyrus. In Study 2, data from 60 patients who were excluded from Study 1 because of motor deficits were analyzed in the same way to determine whether frontal lesions contributed to visual or tactile extinction. Results again demonstrated that tactile extinction is associated with inferior parietal dysfunction, and visual extinction is associated with dysfunction of the visual association cortex. Potential accounts of the results, based on the "hemisphere rivalry" model of extinction and the limited attentional capacity model, are considered.

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

“…Also, in the present study, frontal damage was associated with neglect, as assessed with cancellation tasks rather than with the presence of extinction. However, damage to many different brain regions has been related to neglect,34 35 and studies aiming at isolating brain lesions causing extinction show a comparable variability 9 10 36. Recent methodological lesion-mapping advancements, such as VLSM, now provide a more sensitive approach for relating lesion sites to neurological syndromes and additionally eliminate the appliance of cut-off scores for the definition of patient subgroups which may vary across different studies.…”

Selective Cerebral Volume Reduction in Rett Syndrome: A Multiple-Approach MR Imaging Study

“…Although considerable emphasis has been placed on the association between frontal dysfunction and cognitive and motor deficits, parietal reductions are consistent with deficits in sequential movements and tactile information processing (including pain) that typify RTT. 14,15 The role of the posterior dorsal parietal cortex in the regulation of ocular and limb movement via connections with the premotor cortex is relatively well established, 52,53 and the adjacent inferior parietal lobule is implicated in tactile processing and sensorimotor integration, 54 including hand proprioception for functional object use. 55 Selective anterior frontal reductions in girls with more severe phenotypes may underlie greater cognitive and motor involvement in these individuals.…”

Visuotactile Representation of Peripersonal Space: A Neural Network Study

“…Finally, the strength of the inhibitory synapses (parameter 0 ) has been set small enough to allow a right-hand stimulus and a left-hand stimulus, applied simultaneously, to be perceived as in healthy subjects (Hillis et al, 2006).…”