Submitted on May 27, 2008
Revised on December 3, 2008
Accepted on December 4, 2008
Optokinetic and vestibular responsiveness in the macaque rostral vestibular and fastigial nuclei
Ayanna S Bryan1 and Dora E Angelaki1*
1 Washington University School of Medicine
* To whom correspondence should be addressed. E-mail: angelaki{at}pcg.wustl.edu.
We recorded from rostral vestibular and rostral fastigial nuclei neurons that did not respond to eye movements during three-dimensional (3D) vestibular and optokinetic stimulation (OKS). The majority of neurons in both areas (76% and 69% in VN and FN, respectively) responded during both rotational and translational motion. Preferred directions scattered throughout 3D space for translation but showed some preference for pitch/roll over yaw for rotation. VN/FN neurons were also tested during OKS while monkeys suppressed their optokinetic nystagmus by fixating a head-fixed target. Only a handful of cells (VN: 17%, FN: 6%) modulated during 0.5 Hz OKS-suppression, but the number of responsive cells increased (VN: 40%, FN: 48%) during 0.02 Hz OKS. Preferred directions for rotation and OKS were not matched on individual neurons and OKS gains were smaller than the respective gains during rotation. These results were generally similar for vestibular and fastigial nuclei neurons. We conclude that optokinetic-vestibular convergence might not be as prevalent as earlier studies have suggested.
