Parietal Lobe Lesions Disrupt Saccadic Remapping of Inhibitory Location Tagging

Sapir, Ayelet; Hayes, Amy; Henik, Avishai; Danziger, Shai; Rafal, Robert · 2004 · Crossref

DOI: 10.1162/089892904323057245

archive: archived pipeline: cataloged verified

Get this paper ↗ (DOI — opens at the source; we link to it, we don't host it)

Summary

This study investigates the neural mechanisms underlying saccadic remapping, specifically how the visual system maintains a coherent percept of the environment despite continuous eye movements. The authors focus on Inhibition of Return (IOR), an inhibitory tag that slows responses to previously cued locations to facilitate efficient visual search. While previous research established that IOR is generated via retinotectal pathways to the superior colliculus, it remains unclear how this tag is updated from retinal to environmental coordinates during eye movements. The paper tests the hypothesis that the intraparietal sulcus (IPS) is critical for remapping this inhibitory tag into an environmentally based reference frame. The researchers compared five patients with chronic, unilateral lesions in the IPS region against twelve healthy controls. The experimental paradigm required participants to detect a target appearing in one of four boxes after a non-informative precue. Two conditions were tested: a fixation condition where eyes remained static, and an eye movement condition where participants made a saccade between the cue and target presentation. In the eye movement condition, targets appeared either at the environmental location of the cue (lateralized relative to the new fixation) or the retinal location (projected to the same retinal spot as the cue). Reaction times were measured to determine whether IOR persisted in environmental or retinal coordinates. Results showed that healthy controls exhibited IOR in both environmental and retinal reference frames, confirming that normal subjects successfully remap the inhibitory tag. In contrast, patients with IPS lesions demonstrated IOR only at the retinal location of the cue, failing to show environmental IOR in either the contralesional or ipsilesional visual fields. This deficit was consistent across patients regardless of lesion side, although individual variability was noted. The findings indicate that while the superior colliculus generates the inhibitory tag, the IPS is necessary for updating this information into a stable, environmentally based coordinate system. The study concludes that the intraparietal sulcus serves as the neural substrate for encoding inhibitory spatial tags in environmental coordinates. This suggests that the IPS is not only involved in remapping the visual field during saccades but also in integrating remapped information to guide visual search. The bilateral nature of the deficit in unilateral patients implies that the IPS is required to encode the tag itself, rather than merely remapping it for the contralateral field. These results clarify the division of labor between subcortical structures, which generate the tag, and cortical areas, which maintain its spatial stability across eye movements.

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed.

Summary generated by qwen3.6-27b-prismaquant on 2026-06-25; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• eye movements scanning