August 2010
Volume 10, Issue 7
Free
Vision Sciences Society Annual Meeting Abstract  |   August 2010
Temporal extinction in hemi-neglect patients
Author Affiliations
  • Marie de Montalembert
    Laboratoire Psychologie de la Perception, CNRS & Université Paris Descartes
  • Pascal Mamassian
    Laboratoire Psychologie de la Perception, CNRS & Université Paris Descartes
Journal of Vision August 2010, Vol.10, 1399. doi:10.1167/10.7.1399
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      Marie de Montalembert, Pascal Mamassian; Temporal extinction in hemi-neglect patients. Journal of Vision 2010;10(7):1399. doi: 10.1167/10.7.1399.

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Abstract

Recent neuroimaging and neuropsychological studies have suggested that the right temporo-parietal junction has a dominant role in visual time estimation, suggesting that it forms a core structure of a when pathway. Most of the time, neurological patients with right brain damage present extinction (i.e. when two brief near-simultaneous stimuli are presented they only report the ipsilesional item). In this experiment, we were interested in how hemi-neglect patients with visual extinction deal with the duration estimation of two simultaneous events. For this purpose, we asked participants to compare the duration of two stimuli, a standard and a test (a blue and a red circle) presented in their central visual field at different time durations (test/standard duration: 0.3 to 3.0 sec). We compared the performance of normal observers and left hemi-neglect patients who had a right temporo-parietal stroke or a hematoma and who presented visual extinction. Stimuli were shown diametrically opposed on a virtual circle (radius = 2.6 deg. of visual angle). Simultaneous events were obtained by setting the half duration of the second stimulus at the end of the first stimulus. We found that control participants were almost not impaired to estimate the duration of these two simultaneous events in comparison to sequentially presented stimuli (drop of 3.0% in their duration threshold). In contrast, hemi-neglect patients were significantly more impaired in the simultaneous versus sequential presentation (drop of 7.0% at minimum in their duration threshold). This result is in accordance with previous studies showing the crucial role of the parietal lobe for time estimation. Furthermore, our results show that hemi-neglect is probably not simply a bias in orienting attention to one side of space but a more profound deficit to process simultaneously two objects.

de Montalembert, M. Mamassian, P. (2010). Temporal extinction in hemi-neglect patients [Abstract]. Journal of Vision, 10(7):1399, 1399a, http://www.journalofvision.org/content/10/7/1399, doi:10.1167/10.7.1399. [CrossRef]
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