Neuronal loss in human medial vestibular nucleus

Abstract

The data concerning the effects of age on the brainstem are inconsistent, and few works are devoted to the human vestibular nuclear complex. The medial vestibular nucleus (MVN) is the largest nucleus of the vestibular nuclear complex, and it seems to be related mainly to vestibular compensation and vestibulo-ocular reflexes. Eight human brainstems have been used in this work. The specimens were embedded in paraffin, sectioned, and stained by the formaldehyde-thionin technique. Neuron profiles were drawn with a camera lucida at x330. Abercrombie's method was used to estimate the total number of neurons. We used the test of Kolmogorov-Smirnov with the correction of Lilliefors to evaluate the fit of our data to a normal distribution, and a regression analysis was performed to determine if the variation of our data with age was statistically significant. The present study clearly shows that neuronal loss occurs with aging. The total number of neurons decreases with age, from 122,241 +/- 651 cells in a 35-year-old individual to 75,915 +/- 453 cells in an 89-year-old individual. Neuron loss was significant in the caudal and intermediate thirds of the nucleus, whereas the changes in the rostral third were not significant. The nuclear diameter of surviving neurons decreased significantly with age. There is a neuron loss in the MVN that seems to be age-related. It could help explain why elderly people find it hard to compensate for unilateral vestibular deficits. The preservation of neurons in the rostral third could be related to the fact that this area primarily innervates the oculolmotor nuclei; these latter neurons do not decrease in number in other species studied.

Postural reactions following forward platform perturbation in young, middle-age, and old adults

“…We hypothesized that aging would affect EMG and kinematic patterns of postural responses following forward platform perturbation prior to the sixth decade of life. Structural and functional changes in motor and sensory systems that occur during adulthood (Alvarez et al, 1998(Alvarez et al, , 2000Hakkinen and Hakkinen, 1991;Kido et al, 2004;Low Choy et al, 2007;Rauch et al, 2001;Vandervoort, 1992) support the idea that changes in the postural control system and, specifically, in the ability to react to an unpredictable perturbation would be already apparent even before the beginning of senescence.…”

A multivariate analysis of the effects of aging on glutamate, GABA and arginine metabolites in the rat vestibular nucleus

“…The vestibular sensory hair cells and their afferent connections decrease with age (Gleeson and Felix, 1987;Anniko, 1983;Alidina and Lyon, 1990;Fujii et al, 1990;Lyon and King, 1997;Merchant et al, 2000;Park et al, 2001;Rauch et al, 2001;Kevetter and Leonard, 2002;Lopez et al, 2005;Leonard and Kevetter, 2007). However, neuronal loss has also been reported in the human VNC (Lopez et al, 1997;Alvarez et al, 1998Alvarez et al, , 2000Tang et al, 2001) and in the VNC of some animal species (Sturrock, 1989; see Fernandez et al, 2007 andKevetter et al, 2005 for conflicting evidence in the golden hamster and gerbil, respectively).…”

Immunocytochemical and stereological studies of the rat vestibular nucleus: optimal research methods using glucocorticoid receptors as an example

“…In the study of Alvarez et al (1998), neuronal profiles were drawn with a camera lucida and Abercrombies's method was used to estimate the total number of neurons in the human MVN. There was an assumption in this density study that the neurons were the same size, orientation, and that neuronal distributions were the same in all three dimensions.…”