Line bisection in simulated homonymous hemianopia

Mitra, Anish R; Abegg, Mathias; Viswanathan, Jayalakshmi; Barton, Jason J S (2010). Line bisection in simulated homonymous hemianopia. Neuropsychologia, 48(6), pp. 1742-1749. Oxford: Elsevier 10.1016/j.neuropsychologia.2010.02.023

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Hemianopic patients make a systematic error in line bisection, showing a contra-lesional bias towards their blind side, which is the opposite of that in hemineglect patients. This error has been attributed variously to the visual field defect, to long-term strategic adaptation, or to independent effects of damage to extrastriate cortex. To determine if hemianopic bisection error can occur without the latter two factors, we studied line bisection in healthy subjects with simulated homonymous hemianopia using a gaze-contingent display, with different line-lengths, and with or without markers at both ends of the lines. Simulated homonymous hemianopia did induce a contra-lesional bisection error and this was associated with increased fixations towards the blind field. This error was found with end-marked lines and was greater with very long lines. In a second experiment we showed that eccentric fixation alone produces a similar bisection error and eliminates the effect of line-end markers. We conclude that a homonymous hemianopic field defect alone is sufficient to induce both a contra-lesional line bisection error and previously described alterations in fixation distribution, and does not require long-term adaptation or extrastriate damage.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Ophthalmology
UniBE Contributor:	Abegg, Mathias
ISSN:	0028-3932
Publisher:	Elsevier
Language:	English
Submitter:	Mathias Abegg
Date Deposited:	04 Oct 2013 14:08
Last Modified:	05 Dec 2022 14:00
Publisher DOI:	10.1016/j.neuropsychologia.2010.02.023
PubMed ID:	20188749
Web of Science ID:	000278261900024
URI:	https://boris.unibe.ch/id/eprint/308 (FactScience: 197492)