Background and aims: The subjective straight ahead (SSA), a measure of the representation of body orientation, has been shown to be shifted to the lesion side in neglect patients, and to be influenced by stimulation of sensory systems involved in postural control.
Method: Here, we investigated the influence of changing body orientation in the sagittal plane on the SSA in 21 patients with right hemispheric lesion, of whom 12 had neglect, in comparison with 6 healthy control subjects. In order to quantify both horizontal components of SSA error, i.e. yaw rotation and lateral shift, we used a method requiring the alignment of a luminous rod with SSA.
Results: Neglect patients showed a significant rightward shift in sitting position, which was greatly reduced in supine position. No shift occurred in patients without neglect and controls. Yaw rotation did not reach significance in any group.
Conclusion: The data showed that the body-centred frame of reference, mostly translated in neglect, is strongly improved in supine position. Changing body orientation seems to be a convenient tool to correct the representation of body midline.
- body position
- spatial neglect
- subjective straight ahead