Ipsilateral neglect: Reversal of bias or exaggerated cross-over phenomenon?

Academic Article

Abstract

  • When right brain injury produces contralesional neglect (CN), patients typically misbisect lines to the right. However, others demonstrate so-called 'ipsilateral neglect' (IN) with misbisection to the left of midpoint. Paradoxically, most patients with CN also demonstrate a 'cross-over' phenomenon whereby they misbisect short lines to the left. It is not known whether patients with IN actually have a contralesional bias opposite the ipsilesional bias observed with CN, or if their performance reflects an exaggerated cross-over. These alternatives can be distinguished by power function analysis which evaluates the relationship between magnitude of perception and stimulus magnitude. Using line bisection tasks to derive a power function, an IN patient showed a reduced exponent (β = 0.841), falling outside 95% confidence intervals (CI) for controls but within the CI for CN patients. The IN patient showed a greatly increased constant (K = 7.82), extending outside the CI for both controls and CN patients. The results suggest that the anomalous leftward misbisection with IN is associated with an exaggerated cross-over point and not simply reversal of spatial bias.
  • Authors

    Published In

  • Cortex  Journal
  • Digital Object Identifier (doi)

    Author List

  • Adair JC; Chatterjee A; Schwartz RL; Heilman KM
  • Start Page

  • 147
  • End Page

  • 153
  • Volume

  • 34
  • Issue

  • 1