Contralesional distractors enhance ipsilesional target processing after right-hemispheric stroke

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neurology

Background:

• Stroke, particularly right-hemispheric stroke, often leads to significant deficits in processing information from the contralesional space.
• Understanding how attentional processing is disrupted is crucial for rehabilitation and managing post-stroke cognitive impairments.

Purpose of the Study:

• To investigate the impact of a contralesional distractor on ipsilesional perception in patients with right-hemispheric stroke.
• To compare distractor effects in stroke patients versus healthy elderly controls.
• To correlate behavioral distractor effects with lesion locations using voxel-based lesion-symptom mapping (VLSM).

Main Methods:

• A prospective study involving patients with right-hemispheric stroke and healthy elderly controls.
• A simple target detection task measuring reaction times (RTs) with and without a contralesional distractor.
• Regression analysis relating distractor interference to neglect and extinction measures.
• Voxel-based lesion-symptom mapping (VLSM) to identify lesion correlates of altered distractor processing.

Main Results:

• Healthy controls showed slowed RTs with a contralesional distractor for both left and right targets.
• Right-hemispheric stroke patients only showed slowed RTs for contralesional left targets.
• Crucially, a contralesional distractor significantly expedited ipsilesional (right-sided) target detection in stroke patients.
• This facilitation was linked to lesions in the anterior middle temporal and temporoparietal cortex, internal/external capsule, and superior longitudinal fascicle (SLF).

Conclusions:

• Right-hemispheric stroke disrupts normal attentional processing, altering how contralesional stimuli are prioritized.
• Damage to specific temporal, temporoparietal regions, and white matter tracts may convert contralesional stimuli into non-specific saliency signals.
• This transformation may lead to facilitated information processing in the ipsilesional space following right-hemispheric stroke.