Integration Of Vestibular Information Research Articles

Widespread Vestibular Activation of the Rodent Cortex

Much of our understanding of the neuronal mechanisms of spatial navigation is derived from chronic recordings in rodents in which head-direction, place, and grid cells have all been described. However, despite the proposed importance of self-reference information to these internal representations of space, their congruence with vestibular signaling remains unclear. Here we have undertaken brain-wide functional mapping using both fMRI and electrophysiological methods to directly determine the spatial extent, strength, and time course of vestibular signaling across the rat forebrain. We find distributed activity throughout thalamic, limbic, and particularly primary sensory cortical areas in addition to known head-direction pathways. We also observe activation of frontal regions, including infralimbic and cingulate cortices, indicating integration of vestibular information throughout functionally diverse cortical regions. These whole-brain activity maps therefore suggest a widespread contribution of vestibular signaling to a self-centered framework for multimodal sensorimotor integration in support of movement planning, execution, spatial navigation, and autonomic responses to gravito-inertial changes.

Interaction between Cortical Control of Vestibular Function and Spatial Representation in Man

An asymmetry of the vestibulo-ocular reflex is observed after unilateral posterior cortical lesions in human. The co-occurrence of vestibular deficits and visuo-spatial disorders suggests a functional link between the representation and update of space and the integration of vestibular information in the occipito-parieto-temporal cortex of the right hemisphere.

The Role of Attention in Vestibular Processing

This study investigated the hypothesis that vestibular processing is facilitated by attention, and that suppression of the vestibule-ocular reflex will lead to dual-task interference in a secondary information processing task. Twelve patients with surgically confirmed absent unilateral vestibular function and twelve healthy age-matched controls participated in this study. All subjects underwent vestibular stimulation through two different types of rotational conditions, one a semicircular canal stimulus and the other an otolith stimulus, two different visual conditions (darkness and fixation of a laser point) and pursuit tracking of a moving laser point. Subjects also performed one of three different secondary information processing tasks (IPT) while undergoing the vestibular condition. The results of this study showed that dual-task interference occurs during vestibular stimulation in both patients and healthy controls, and this interference was more pronounced in patients during more complex IPTs. The results also found no overall difference in performance of a secondary cognitive task when subjects suppressed the vestibule-ocular reflex by fixating during rotation. These results may suggest that cognitive processing is a necessary component for integration of vestibular information, and this requirement may be greater in patients with unilateral vestibular loss.