Quantitative analysis of the Golgi impregnated human (neo)striatal neurons: Observation of the morphological characteristics followed by an emphasis on the functional diversity of cells.

BACKGROUND: The (neo)striatum is the major input structure of the basal nuclei, which is involved in the execution of voluntary movements, but also in controlling the processes that lead to the movement, such as motivation and cognition. The striatum provides its function through an interaction between projection neurons and interneurons. The aim of this study was to quantify the morphological properties of neurons in the precommissural putamen and precommissural caudate nucleus head and to evaluate whether there is a difference in cell morphology between different cell groups within one part and between the same cell groups within different parts of the striatum. METHODS: A total of 652 neuronal images of human striatum were observed. The features of the neuronal morphology (soma size, dendritic field size, shape of neuronal image, dendritic curviness, dendritic branching complexity) were observed by determining appropriate parameters of digital images of neurons. RESULTS: According to the presence of spines on the soma and/or dendrites, neurons were qualitatively classified into 446 spiny and 206 aspiny cells. The analysis of the distribution of the dendritic field area shows that spiny and aspiny neurons from both parts of the neostriatum can be decomposed into two distributions, which means that they can be classified into subgroups. A quantitative analysis of the spiny/aspiny neurons in the human putamen or caudate nucleus head has shown that there is a statistically significant difference between them. By comparing the morphology of neurons of the same group between different parts of the human neostriatum (putamen and caudate nucleus), it was also determined that there is a statistically significant difference. CONCLUSION: Since the morphology and function of neurons are in close correlation, it can be assumed that different groups of neurons in the human striatum might support functional diversity of the studied area.

Mathematical modelling of transformations of asymmetrically distributed biological data: an application to a quantitative classification of spiny neurons of the human putamen.

Many measurements in biology follow distributions that can be approximated well by the normal distribution. The normal distribution plays an extremely important role in probability theory. However, some of the experimental data in biology are distributed asymmetrically. In order to transform such an asymmetrical distribution into a normal distribution, for which the standard statistical tables can be used for probability analysis of the available data, one must choose suitable transformation functions. We have met this problem when we qualitatively classified the spiny neurons in the adult human putamen. But, if one tries to test a qualitative classification of neurons quantitatively, a considerable class overlap between cells occurs as well as asymmetry often appears in the distributions of the data. We have already offered a method to overcome the overlapping problem when the data distributions are normal. In order to resolve the asymmetry problem in data distribution, we transformed our asymmetrically distributed data into an approximately normal distribution using a family of simple power functions and on a basis of appropriate probability analysis we propose a more acceptable classification scheme for the spiny neurons. The significance of our results in terms of current classifications of neurons in the adult human putamen is discussed.

Application of fractal analysis to neuronal dendritic arborisation patterns of the monkey dentate nucleus.

The deep nuclei of the cerebellar cortex have not yet received adequate exploratory attention. An exception is represented by the pioneering work of Chan-Palay, published in 1977, on the dentate nucleus morphology. She has classified each individual cell in the dentatus of the monkey into one of six types. Although fractal analysis is presently the most prominent quantitative method for morphometric neuronal studies, no article referring to applications of this method to the analysis of cell types of the dentate nucleus has so far been published. In the present study we apply fractal analysis to this unsolved problem and calculate the fractal dimension for each dendritic arbour of a neuron. We will hereby prove that by application of fractal analysis to the dendritic arbours of these cells whilst ignoring other neuronal attributes allows for clear discrimination of only three cell types.

Neuronal images of the putamen in the adult human neostriatum: a revised classification supported by a qualitative and quantitative analysis.

A qualitative analysis of the morphology of human putamen nerve cells involves a detailed description of the structure and features of neurons and, accordingly, their classification into already defined classes and types. In our sample of 301 neurons, 64.78 % (195) were spiny and 35.22 % (106) aspiny cells. By analyzing cell bodies and dendritic trees, we subdivided spiny cells into two types (I and II) and aspiny cells into three types (III, IV and V). Our sample of neurons, classified according to the previously described scheme, consisted of 80 type I, 115 type II, 16 type III, 42 type IV and 48 type V nerve cells. In the present study, after qualitative analysis of microscopic images of the Golgi impregnated neurons of the putamen, we measured/quantified five morphological properties, i.e., the sizes of the soma and dendritic field, shape of the neuron, straightness of individual dendrites and the branching complexity of the dendritic tree, using eight morphometric parameters. Hence, we identify five types of nerve cells in the human putamen: type I-small spiny neurons; type II-large spiny neurons; type III-large aspiny neurons; type IV-neurons with a large soma and a medium dendritic field; and type V-small aspiny neurons. By performing an adequate statistical analysis on these parameters, we point out that the proposed types differ enough in their morphology to warrant our qualitative classification.

[Quantitative analysis of the change in neuronal numerical density of the human nucleus dentatus within development].

BACKGROUND/AIM: The role of the dentate nucleus is to coordinate input information coming from the lower olivary complex and various parts of the brainstem of the spinal marrow with the output information from the cerebellar cortex. To better understand functions and relations of the dentate nucleus it is highly important to study its development process. The aim of this study was to determine a possible mathematical model of decrease in neuronal numerical density of the human nucleus dentatus at different stages of development. METHODS: This study included 25 fetal brains of different age (12.5-31 weeks of gestational age and one brain of a 6-day-old newborn). The brains were fixed in 10% formalin-alcohol solution and embedded in paraffin. Sections were cut at a thickness of 6, 15, and 30 microm and stained with cresyl violet. Each fifth section was analyzed using a light microscope, and numerical density of dentate nucleus neurons was established using the M42 Weibel's grid system. RESULTS: The obtained results revealed a constant decrease in numerical density value. The changes of numerical densities at different stages of development correspond with Boltzmann function principles. The first, almost perpendicular part of Boltzmann function corresponds with the development of the dorsomedial lamina and the appearance of ventrolateral lamina primordium. The second, more or less horizontal part of Boltzmann function corresponds with the development of both laminae. CONCLUSION. The obtained results indicate that Boltzmann function can be considered a mathematical model of change in neuronal numerical density of dentate nucleus at different stage of development.

[Quantitative analysis of dendritic branching pattern of large neurons in human cerebellum].

BACKGROUND/AIM: Dentate nucleus (nucleus dentatus) is the most distant of the cerebellar nuclei and the major system for information transfer in the cerebellum. So far, dendritic branches of four different kinds of large neurons of dentate nucleus, have been considered mainly qualitatively with no quantification of their morphological features. The aim of the study was to test the qualitative hypothesis that the human dentate nucleus is composed of various types of the large neurons by quantitative analysis of their dendritic branching patterns. METHODS: Series of horizontal sections of the dentate nuclei were taken from 15 adult human brains, free of diagnosed neurological disorders. The 189 Golgi-impregnated images of large neurons were recorded by a digital camera connected to a light microscope. Dendritic branching patterns of digitized neuronal images were analyzed by modified Sholl and fractal analyses. RESULTS: The number of intersections (N(m)), critical radius (r(c)) and fractal dimension (D) of dendritic branching pattern for four types of the large neurons were calculated, statistically evaluated and analyzed. The results show that there is a significant difference between four neuronal types in one morphometric parameter at least. CONCLUSION: The present study is the first attempt to analyze quantitatively the dendritic branching pattern of neurons from the dentate nucleus in the human. The hypothesis that the four types of the large neurons exist in this part of human cerebellum is successfully supported.

[Critical periods during development of the dentate nucleus and their clinical significance].

INTRODUCTION: The aim of this study was to identify the critical periods in the development of the human dentate nucleus in fetuses of different gestational ages and in one newborn brain. MATERIAL AND METHODS: The fetal brains were fixed in alcohol-formalin-acetic acid, embedded in paraffin, cut into 30 micro sections, and stained with cresyl violet. The sections were examined by light microscopy. In order to identify vulnerable periods, histological and stereological analyses were done. FORMATION OF THE DENTATE NUCLEUS: The first appearance of the dentate nucleus was noticed in fetus of 12.5 weeks of gestation (wg), and its cells corresponded to the first and second stage of maturation. Formation of the dorsomedial lamina begins at the end of the 13th wg, and it starts to fold at 19.5 wg. At this time, cells correspond to the third stage of maturation, and formation of the ventromedial lamina begins. The first folds of the ventromedial lamina are noticed at 23.5 wg. Fourth stage maturity cells are noticed at 23.5 wg. remaining conspicuous up to birth. The numerical density of the nerve cell nuclei shows a constant decrease. CONCLUSION: Based on our results, we can conclude that during development of the dentate nucleus, there are two vulnerable periods. The first one corresponds to the fourth month of intrauterine life, and the second to the intensive growth of the dorsomedial and ventrolateral lamina (20.0 - 24.5 wg).