Line bisection in the split brain.
The authors examined line bisection in 4 patients with resection of the corpus callosum and in 22 control participants. The control participants showed a leftward bias, especially with the left hand, implying right-hemispheric dominance in spatial attention. Two patients with anterior callosotomy showed similar biases, suggesting that the anterior callosum plays only a small role. A patient with complete callosotomy showed a strong right bias, regardless of hand use. A patient with posterior callosotomy showed the opposite pattern: a strong left bias, regardless of hand use. These data suggest that the posterior corpus callosum normally plays a role in line bisection and that the resection of the posterior corpus callosum produces consistent bias. The direction of the bias depends on which hemisphere assumes control.
Hausmann
Markus
M
Department of Psychology, University of Auckland, Auckland, New Zealand. markus.hausmann@ruhr-uni-bochum.de
Corballis
Michael C
MC
Farbi
Mara
M
D000328:Adult; D003337:Corpus Callosum / Q000502:physiology*; D004827:Epilepsy / Q000601:surgery; D005556:Form Perception / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D019635:Neurosurgical Procedures; D012727:Sex Characteristics; D014794:Visual Fields / Q000502:physiology