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Following parietal damage most patients with visual neglect bisect horizontal lines significantly away from the true centre. Neurologically intact individuals also misbisect lines; a phenomenon referred to as ‘pseudoneglect’. In this study we examined the relationship between neglect and pseudoneglect by testing how patterns of pre-existing visuospatial asymmetry predict asymmetry caused by parietal interference. Twenty-four participants completed line bisection and Landmark tasks before receiving continuous theta burst stimulation to the left or right angular gyrus. Results showed that a pre-existing pattern of left pseudoneglect (i.e. right bias), but not right pseudoneglect, predicts left neglect-like behaviour during line bisection following right parietal cTBS. This correlation is consistent with the view that neglect and pseudoneglect arise via a common or linked neural mechanism. [ABSTRACT FROM AUTHOR]

Abstract: Line bisection is widely used to diagnose and quantify hemispatial neglect, yet there is little consensus as to the cognitive mechanisms used to perform this simple task. Current cognitive accounts have been deduced solely from behavioural measures. The aim of this study was to discover if subject''s own knowledge of the mental strategies used to perform the task actually informs behavioural performance. One hundred and forty healthy volunteers bisected a set of lines and were asked to describe the mental strategies used. Three distinct strategies were identified. These were (1) comparing two segments, (2) computing the centre of mass, and (3) externally centred strategies. Strategies 1 and 2 have previously been described but externally centred strategies have not been reported as a distinct strategy in bisection. Although none of the three strategies predicted performance this may have been due to the fact that 44% of subjects failed to describe any strategy. Men and women bisected lines equally well, however more men than women reported use of externally centred strategies. [Copyright &y& Elsevier]