Time course of eye and head deviation in spatial neglect

Spatial neglect is characterized by a deviation of the eyes and the head during active search, as well as at rest. Here the authors investigate the hitherto unknown relationship between these striking behaviors in the course of recovery. Gaze, eye-in-head, and head-on-trunk positions were recorded separately under two experimental conditions: (i) at rest (i.e., without any specific requirements, doing nothing) and (ii) during active exploratory search in a large visual array of 240 degrees x 80 degrees over a 10-month period. The authors observed a parallel decrease of eye and head (= gaze) deviation in both conditions, accompanied by a comparable decline in neglect severity. The results strengthen the view that the marked gaze deviation toward the ipsilesional side in patients with spatial neglect is due to a very elementary disturbance of human spatial information processing.