Modulation by horizontal eye position of the vestibulo-collic reflex induced by tilting in the frontal plane in the alert cat.

In alert cats, during sinusoidal rotations of head and trunk en bloc around a longitudinal axis, in darkness or in light, the vestibulo-collic reflex induces neck muscle contractions. The phase and gain diagrams are consistent, in the frequency range 0.2 to 1.2 Hz, with previous results from anesthetized or decerebrate cats. In addition, neck muscle contractions are modulated by horizontal eye position, as is the case for rotations in the horizontal plane, around the vertical (Z) axis. Neck muscle contraction is consequently under control of both eye position and head tilt angle. This synergy of eye and head could suppress the effects of vestibulo-collic reflex during orienting reactions.