Benchmarking of tools for axon length measurement in individually-labeled projection neurons

Projection neurons are the commonest neuronal type in the mammalian forebrain and their individual characterization is a crucial step to understand how neural circuitry operates. These cells have an axon whose arborizations extend over long distances, branching in complex patterns and/or in multiple brain regions. Axon length is a principal estimate of the functional impact of the neuron, as it directly correlates with the number of synapses formed by the axon in its target regions; however, its measurement by direct 3D axonal tracing is a slow and labor-intensive method. On the contrary, axon length estimations have been recently proposed as an effective and accessible alternative, allowing a fast approach to the functional significance of the single neuron. Here, we analyze the accuracy and efficiency of the most used length estimation tools—design-based stereology by virtual planes or spheres, and mathematical correction of the 2D projected-axon length—in contrast with direct measurement, to quantify individual axon length. To this end, we computationally simulated each tool, applied them over a dataset of 951 3D-reconstructed axons (from NeuroMorpho.org), and compared the generated length values with their 3D reconstruction counterparts. The evaluated reliability of each axon length estimation method was then balanced with the required human effort, experience and know-how, and economic affordability. Subsequently, computational results were contrasted with measurements performed on actual brain tissue sections. We show that the plane-based stereological method balances acceptable errors (~5%) with robustness to biases, whereas the projection-based method, despite its accuracy, is prone to inherent biases when implemented in the laboratory. This work, therefore, aims to provide a constructive benchmark to help guide the selection of the most efficient method for measuring specific axonal morphologies according to the particular circumstances of the conducted research.

The Impact of the Image Resolution on the Value of Measured Geometric Parameters on the Example of Ductile Iron Structure

Paper presents the influence of the image resolution on measurement geometric parameters of the objects. Employing as test images the ductile iron structure images allow to analyze the effect of resolution distortion on a model of objects with regular shape. Authors showed on the example images, how decreasing resolution of digital images distorts the value of the parameters describing the shape of the objects, its perimeter and its quantity. The analysis was performed by an automatic algorithm applying image analysis and stereological method.

The effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on mice myocardial morphology

ABSTRACT: Studies have demonstrated sympathetic cardiac denervation in the MPTP mouse model. MPTP toxicity causes sympathetic nerve damage and depletion of heart norepinephrine. Previous evaluations of impairments in heart innervation have been based on imaging, electrophysiological and biochemical methods. However, these studies lacked information that can be obtained from morphoquantitative analyses. Thus, this study aimed to apply a design-based stereological method for evaluating the morphoquantitative alterations of myocardium following treatment with the neurotoxin MPTP in the C57/BL mouse. Our results showed that MPTP reduced the number of cardiomyocytes in the left ventricle.

Cerebellar volume in early-onset schizophrenia and its association with severity of symptoms

Objectives This study aimed to investigate whether early-onset schizophrenia (EOS) cases differ from controls regarding volumes of the total cerebellum and the right and left cerebellar hemispheres, and volumetric asymmetry. Correlations of cerebellar volumes and asymmetry indices with severity of symptoms and general functioning in cases of EOS were also assessed. Methods Adolescents with EOS (n = 23) were compared with controls (n = 23). Sociodemographic and clinical data, and magnetic resonance imaging scans that were acquired for routine clinical purposes were collected retrospectively. Cerebellar volumes were evaluated using the stereological method. Asymmetry indices were subsequently calculated. Scores of the Positive and Negative Syndrome Scale and the Children’s Global Assessment Scale were used to assess the severity of symptoms and general functionality. Results There were no significant differences in any of the cerebellar volumes and asymmetry indices between the two groups. Neither cerebellar volumes nor asymmetry indices were correlated with the severity of symptoms and general functionality in EOS. Conclusions Our findings suggest that the early-onset form of schizophrenia does not show apparent volumetric changes of the cerebellum. Additionally, the neural circuits involved in formation of symptomatology may not reflect any correlation with cerebellar volumes at mid-adolescence.

Method for the simulation and reconstruction of 3D particle size distributions in metal structures

The stereological method for studying grain structures is presented, it determines the interrelation between the size distributions of three-dimensional grains and their planar and linear sections. Method is applicable for both reconstruction and simulation of the 3D structures. The polyhedral shape of the grains is taken into account by means of the shape factors established for them. An original method to determine the distribution of plane sections from the certain grain-polyhedron to calculate the shape factors is presented. This method can be used to describe the shape of different structural components in many materials: steels, cast irons, concretes, rocks, ceramics, open-porosity materials, biofilms, foams, etc. The stereological method is also applicable to structures with spherical particles, for which the shape factors are equal to unity. The method makes it possible to create the standards of plane sections of grain structures and other structures with a previously known size distribution of 3D grains or particles.