Search patterns using the line bisection test for neglect

Neglect has been attributed to sensory-attentional, motor-intentional, and representational disorders. Although patients with neglect may have defective visual exploration, the nature of this exploration deficit has not been entirely elucidated. The purpose of this study is to learn how, compared with control subjects, a patient with neglect performs visual exploration.

The line bisection test is commonly used to detect and evaluate the performance of patients with unilateral or hemispatial spatial neglect. We tested an experimental subject with left premotor-intentional neglect using an infrared eye monitoring instrument. Thirteen right-handed healthy volunteers served as control subjects. From different starting ocular positions, we assessed the direction of eye movements when the subjects initially oriented to the line, scanned the line, and then attempted to look at the center of the line.

Independent of starting ocular position, normal subjects most often initially orient to the left end of the line, scan rightward, then look leftward to the center. However, the eye movements in our experimental subject with neglect were directed to the right end of the line without any scanning or leftward eye movement back to the center of the line.

Our subject with neglect had defective line exploration that may be attributed to a directional ocular motor intentional deficit.