[Abstract Title]. - Society for Neuroscience

FNRS (Belgium), ESA (EU)
Title: Compensation for smooth eye and head movements by gaze saccades during headunrestrained
tracking
Authors: *P. M. DAYE 1 , G. BLOHM 2 , P. LEFÈVRE 2 ;
1 CESAME-UCL, Univ. Catholique Louvain, Louvain-la-Neuve, Belgium; 2 CESAME, Univ.
Catholique de Louvain, Louvain-la-Neuve, Belgium
Abstract: Gaze saccades are generally composed of a combination of eye and head movements.
In head fixed conditions, smooth eye movements that occur during the saccade latency period are
taken into account by the saccade if the nervous system has enough time to integrate eye
velocity. In the present study we investigate this compensatory mechanism when the head was
unrestrained in order to possibly differentiate the compensation for eye movements from the
compensation for head movements occurring during the saccade latency period. Subjects sat in
front of a 1-m distant tangential screen. They were instructed to pursue with their eyes and head
a sinusoidal target (Frequency [0.6 to 1.2 Hz]) moving along a straight line in 2D (Orientation [0
to 360°] and amplitude [20 to 25°] randomly chosen). 1.2-1.8s after target motion onset, a second
target was briefly flashed at a random position on the screen. The position of both eyes was
recorded by a video-based recording device (200 Hz), head position was recorded by active
infrared marker tracking cameras (200 Hz) and gaze orientation was reconstructed (Ronsse & al.,
2007). We analyzed how the orienting gaze shift towards the flash was programmed and how
these saccades compensated for the smooth eye (SED) and head (SHD) displacements during the
latency period. Multiple regression analysis (R=0.94, N=899, p