Callosal disconnection neglect: reassessment after 34 years

In 1984, Watson and Heilman reported a patient with a partial callosal disconnection following an infarction of the anterior portion of her corpus callosum. This woman's performance on line-bisection tasks revealed "callosal disconnection neglect." The objective of this research is to reexamine this woman 34 years after her callosal disconnection to gain information about her recovery. The patient completed visual line-bisection tasks in which horizontal lines were placed in the right, left, and center hemispaces and she performed these bisections using her right or left hand. Unlike her performance 34 years ago in which each hand deviated to its ipsilateral hemispace, with greater deviation when lines were placed in the contralateral rather than ipsilateral hemispace, currently, there were no significant main effects for hand or spatial position. Thus, there were notable differences between this woman's most recent performance on the line bisection and her previous performance 34 years ago. Unlike her prior testing 34 years back, this woman's most recent performance resembled the performance of a previous tested healthy control group for whom differences in hand and hemispace were not found. It remains unclear whether her callosal disconnection neglect improved because each hemisphere learned to allocate ipsilateral spatial attention or because she learned a compensatory strategy in which she turned her body so that the lines placed in her right or left hemispace were now toward her midline.