Navigation strategies in patients with vestibular loss tested in a virtual reality T-maze.

During navigation, humans mainly rely on egocentric and allocentric spatial strategies, two different frames of reference working together to build a coherent representation of the environment. Spatial memory deficits during navigation have been repeatedly reported in patients with vestibular disorders. However, little is known about how vestibular disorders can change the use of spatial navigation strategies.

Impaired Attentional Processing During Parabolic Flight.

Previous studies suggest that altered gravity levels during parabolic flight maneuvers affect spatial updating. Little is known about the impact of the experimental setting and psychological stressors associated with parabolic flight experiments on attentional processes. To address this gap, we investigated the level of alertness, selective and sustained attention in 1 and 0 g using a Go/No-Go Continuous Performance Task.

Critical Flicker Fusion Frequency: A Marker of Cerebral Arousal During Modified Gravitational Conditions Related to Parabolic Flights.

evaluation of human brain performance and arousal remains challenging during operational circumstances, hence the need for a rapid, reliable and reproducible tool. Here we hypothesized that the Critical flicker fusion frequency (CFFF) reflecting/requiring visual integration, visuo-motor skills and decision-taking process might be a powerful, fast and simple tool in modified gravity environments. Therefore 11 male healthy volunteers were assessed for higher cognitive functions with CFFF during parabolic flights.

The balance of sleep: Role of the vestibular sensory system.

The vestibular system encodes linear and angular head motion supporting numerous functions from gaze stabilization and postural control, to high-level cortical functions involving spatial cognition, including self-body perception, verticality perception, orientation, navigation and spatial memory. At the brainstem and mesencephalic levels, the vestibular organs also influence postural blood pressure regulation, bone density and muscle composition via specific vestibulo-sympathetic efferences and have been shown to act as a powerful synchronizer of circadian rhythms. Here, we review the evidence that sleep deprivation and sleep apnea syndrome alter vestibular-related oculo-motor and postural control, and that, in turn, vestibular pathologies induce sleep disturbances.

Cooperation of the vestibular and cerebellar networks in anxiety disorders and depression.

The discipline of affective neuroscience is concerned with the neural bases of emotion and mood. The past decades have witnessed an explosion of research in affective neuroscience, increasing our knowledge of the brain areas involved in fear and anxiety. Besides the brain areas that are classically associated with emotional reactivity, accumulating evidence indicates that both the vestibular and cerebellar systems are involved not only in motor coordination but also influence both cognition and emotional regulation in humans and animal models.

Differential regulation of NMDA receptor-expressing neurons in the rat hippocampus and striatum following bilateral vestibular loss demonstrated using flow cytometry.

There is substantial evidence that loss of vestibular function impairs spatial learning and memory related to hippocampal (HPC) function, as well as increasing evidence that striatal (Str) plasticity is also implicated. Since the N-methyl-d-aspartate (NMDA) subtype of glutamate receptor is considered essential to spatial memory, previous studies have investigated whether the expression of HPC NMDA receptors changes following vestibular loss; however, the results have been contradictory. Here we used a novel flow cytometric method to quantify the number of neurons expressing NMDA receptors in the HPC and Str following bilateral vestibular loss (BVL) in rats.

Effects of acute altered gravity during parabolic flight and/or vestibular loss on cell proliferation in the rat dentate gyrus.

Both parabolic flight, i.e. a condition of altered gravity, and loss of vestibular function, have been suggested to affect spatial learning and memory, which is known to be influenced by neurogenesis in the hippocampus.

Vestibular loss promotes procedural response during a spatial task in rats.

Declarative memory refers to a spatial strategy using numerous sources of sensory input information in which visual and vestibular inputs are assimilated in the hippocampus. In contrast, procedural memory refers to a response strategy based on motor skills and familiar gestures and involves the striatum. Even if vestibular loss impairs hippocampal activity and spatial memory, vestibular-lesioned rats remain able to find food rewards during complex spatial memory task.