The importance of spatial learning and the growth of the hippocampal cells within an otoconia defici

A vestibular patient with oscillopsia continual oscillation of the visual field might be expected to have difficulty with this. Nevertheless postnatally flown rats showed impaired maturation in the acquisition of adult tactics of surface righting, and the pups flown until PND30 were definitely unable to perform adult tactics for surface righting Walton et al.

Importantly, because tasks of this type are administered via a computer program and interface experimental conditions can be controlled precisely, and can also be easily coupled with measures of functional brain activity Cornwell et al.

Thus these neurons provide a coordinate reference frame for navigation.

Vestibular system function

The comparative development of guinea pig and rat shows a typical example of the difference in the level of maturity at birth. During locomotion in an open field, hippocampal responses in a given place are the same regardless of the orientation of the head, and hence the view perceived by the rat, which is a form of abstraction Wiener, Except for the exposure of peri-adolescent mice to short episodes of acute centrifugation Francia et al. Yoder and Taube studied HD cells in a mouse strain with nearly complete absence of otoconia and hence minimal otolith function. At E11 the endolymphatic canal forms, and anterior and posterior semi-circular canals appear at E These then are associated with psychiatric problems such as agoraphobia such environments provide troubling cue conflicts , excessive fatigue, depression, and anxiety. Even rats exposed to microgravity only during their postnatal development from PND8 to PND24 showed markedly smaller vestibular cell bodies and less growth of dendritic cell branching with a lack of development, paucity of cerebellar projections to vestibular nuclei Raymond et al. General movements emerge between E24 and E34 in guinea pig fetuses. Development as adaptation: a paradigm for gravitational and space biology, in Experimentation with Animal Models in Space.

For example, the gaze and fixation problems associated with vestibular dysfunction can lead to reading problems requiring specific therapy Braswell and Rine, The development in hypergravity also provoked a substantial delay of the development and strong perturbations of monoaminergic projections to the spinal cord in newborn rats centrifuged 1.

Due to the competition of sensory entries for neural targets during the critical periods, the overstimulated otolith structures should be overrepresented in vestibular nuclei and brain targets, at the detriment of the canalar afferences.

Hippocampal place responses were recorded under light conditions, and they persisted in complete darkness.

vestibular sense

Giedd et al. Information was more easily obtained from ground experiments using centrifuges to produce hypergravity. Newcombe et al. These studies suggested that altering gravity perturb the connectivity of vestibulo-spinal pathways. At the age of 2 months they were not impaired in vestibular response, but showed a tendency to react slower during free fall that was supposed to result from a perturbation of the connections between vestibular, cerebellar and motor structures Bojados and Jamon, The peripheral sensory organ adapts to the level of gravity by adjusting the mass of otoconia and the innervation of sensory epithelium.

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The development of vestibular system and related functions in mammals: impact of gravity