Abnormally speeded saccades to ipsilesional targets in patients with spatial neglect

Natale, E., Marzi, C. A., Bricolo, E., Johannsen, L. and Karnath, H.-O. (2007) Abnormally speeded saccades to ipsilesional targets in patients with spatial neglect. Neuropsychologia, 45 (2). pp. 263-272. ISSN 0028-3932

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Abstract

We mapped the distribution of saccadic reaction times (SRTs) in the visual field of patients with spatial neglect in order to characterise the topography of the bias in spatial orientation peculiar to this disorder. LED-generated stimuli were lit randomly in one of four positions (±5°, ±10°, ±20°, ±30°) along the horizontal meridian in blocks of either ipsilesional or contralesional presentations. Patients were asked to move the gaze as quickly as possible from central fixation to target upon its appearance. Unlike control subjects, patients with neglect showed an asymmetric distribution of visuo-motor performance in the two hemifields with an increasing impairment in target detection and saccadic reaction at increasing eccentricities in the contralesional field. In contrast, in the ipsilesional field they showed abnormally speeded SRTs at 5° and 10°, outperforming even healthy subjects. Latency of saccades increased again at more peripheral ipsilesional locations (20° and 30°) where there was also a tendency for a higher omission rate as compared to control groups. These results indicate that in neglect patients the spatial orientation bias, as witnessed by saccadic performance, specifically affects an off-centred sector of the ipsilesional space, and this is in keeping with evidence from a previous study using a manual RT paradigm. The generality of this phenomenon across different types of motor response suggests that it depends upon abnormal mechanisms of spatial coding interfering with perceptual processing and orienting behaviour.

Item Type: Article
Uncontrolled Keywords: right hemisphere,saccadic execution,saccadic reaction time,spatial neglect,visual orienting,behavioral neuroscience,neuropsychology and physiological psychology ,/dk/atira/pure/subjectarea/asjc/2800/2802
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Depositing User: LivePure Connector
Date Deposited: 23 Jul 2018 09:30
Last Modified: 22 Apr 2020 06:52
URI: https://ueaeprints.uea.ac.uk/id/eprint/67765
DOI: 10.1016/j.neuropsychologia.2006.07.008

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