Differential processing of semicircular canal signals in the vestibulo- ocular reflex

Abstract

Selective semicircular canal inactivation and three-dimensional eye movement recordings have been used to investigate the spatial organization of vestibular signals in the vestibulo-ocular reflex (VOR) of rhesus monkeys. In animals with one pair of semicircular canals inactivated, afferent activity no longer codes all spatial components of head angular velocity. if it were the activation pattern of semicircular canal afferents alone that determines VOR slow phase eye velocity, the head velocity components along the sensitivity vectors of the remaining intact semicircular canals would determine the orientation of slow phase eye velocity. Thus, angular head velocity and slow phase eye velocity would not necessarily always align. Alternatively, if vestibulo-ocular signals coded absolute angular head motion in space based on both semicircular canal and otolith afferent information, one might expect a spatial transformation of the encoded head angular velocity signals such that slow phase eye velocity and angular head velocity continue to spatially align. Examination of the VOR at different frequencies between 0.01 Hz and 1 Hz revealed a frequency-specific spatial organization of vestibulo-ocular signals. Mid and high frequency vestibulo-ocular responses were determined exclusively by the orientation of the sensitivity vectors of the remaining intact semicircular canals. In contrasts, low frequency vestibulo-ocular responses were largely determined by the orientation of the head relative to gravity. These low frequency responses after selective semicircular canal inactivation could be predicted and simulated by a simple model where semicircular canal signals are spatially transformed from a head-fixed to a space-fixed (inertial) representation of angular head velocity. These findings suggest that low frequency vestibulo-ocular responses are dominated by inertial vestibular signals that detect absolute head motion in space based on both semicircular canal and otolith afferent information. Inertial vestibular signals are likely to contribute to head control and motor coordination of gaze, head and body posture.

Reflex control of the spine and posture: a review of the literature from a chiropractic perspective

“…The visual and vestibular systems interact primarily through a series of reflexes and tracts, namely the vestibulo-ocular reflex [56-62], the vestibulospinal tract [50,63], and the dorsal and ventral spinocerebellar tracts [64-69]. …”

“…The vestibulo-ocular reflex may be subdivided into three major components: 1) the rotational vestibulo-ocular reflex, which detects head rotation through the semicircular canals, 2) the translational vestibulo-ocular reflex, which detects linear acceleration of the head via the utricle and saccule, and 3) the ocular counter-rolling response, or optokinetic reflex, which adapts eye position during head tilting and rotation [50]. Through detection of head orientation in space, the vestibular apparatus transmits this information to the vestibular nuclei, where connections with the visual field aid in the correction and coordination of head and body posture via the vestibulo-ocular reflex [56]. The cerebellar flocculus may ultimately be responsible for integrating and executing the efferent corrections of the vestibulo-ocular reflex.…”

Retinoic Acid Deficiency Impairs the Vestibular Function

“…4). Semicircular canals are responsible for angular acceleration detection (Adrian, 1943;Goldberg and Fernandez, 1971;Angelaki et al, 1995). A normal morphology of the three cristae was observed in both wild-type and mutant mice ( Fig.…”

“…In these otolithic organs, sensory hair cells in the neuroepithelial maculae detect gravity and linear acceleration. Above the maculae, embedded in a layer of acellular matrices, lie the otoconia, crystalline structures that act as inertial masses subject to the effects of gravity and shifting in response to linear acceleration (Adrian, 1943;Fernández et al, 1972;Fernández and Goldberg, 1976;Lim, 1984;Angelaki et al, 1995;Jones et al, 2005).…”

What Peripheral Vestibular Manipulations Reveal about the Function and Plasticity in the Primate Oculomotor System

“…Theory predicts that there would be a 1 90% attenuation of rotational vestibulo-ocular reflex (RVOR) in rhesus monkeys at frequencies below 1 Hz but that attenuation above 1 Hz would be less. These predictions have been proven experimentally [11,[13][14][15] .…”