Analysis of morphological features of thalamocortical neurons from the ventroposterolateral nucleus of the cat

Abstract

Morphological features of the dendritic arborization can affect neuronal responses and thus the input-output function of a particular neuron. In this study, morphological data of eight fully reconstructed thalamocortical (TC) neurons from the ventroposterolateral (VPL) nucleus of adult cats have been analyzed. We examined several geometrical and topological parameters, which have been previously shown to have a high impact on the neuron firing pattern and propagation of signals in the dendritic tree. In addition to well-known morphological parameters such as number of dendritic trees (8.3 +/- 1.5) and number of branching points (80-120), we investigated the distribution of dendritic membrane area, branching points, geometrical ratio, asymmetry index, and mean path length for all subtrees of the TC neurons. We demonstrate that due to extensive branching in proximal and middle dendritic sections, the maximum value of the dendritic area distribution is reached at 120-160 mum from the soma. Our analysis reveals that TC neurons are highly branched cells and their dendritic branching pattern does not follow Rall's 3/2 power rule; average values at proximal vs. distal dendritic sections were different. We also found that the dendritic branching pattern of each subtree of the cell had a wide range in symmetry index, whereas the mean path length did not show a large variation through the dendritic arborizations.

Conserved properties of dendritic trees in four cortical interneuron subtypes

“…While some attempts have been made to measure the diameter of parent and daughter branches using light microscopy, it is still controversial whether branch points in real neurons follow precise rules, such as Rall's 3/2 power law21222324. We analyzed EM 3D-reconstructions of dendritic branch points (Fig.…”

Brain Lateralization: A Comparative Perspective

“…As briefly mentioned in section II, both the optic tectum, the nucleus rotundus, and the associated nucleus subpretectalis have larger somata at the visual input level on the left (145,180,304,305). Soma size correlates with the extent of the dendritic arbor (212,363,528). Thus structural asymmetries that occur at brain stem and thalamic level of a sensory system make it likely that bottom-up signals are processed in a lateralized manner.…”

A Topological Representation of Branching Neuronal Morphologies

“…The analysis of complex branching structures, such as branched polymers (Alexandrowicz 1985 ), viscous fingering (Agam et al 2002 ), and fractal trees (Mandelbrot and Freeman 1983 ), is essential for understanding a great variety of physical and biological processes. For example, the fundamental units of the nervous system, neurons, possess highly ramified arborizations (Jan and Jan 2010 ) that are thought to reflect their involvement in different computational tasks (Cuntz et al 2007 ; Zomorrodi et al 2010 ; Van Elburg and Van Ooyen 2010 ; Ferrante et al 2013 ). In order to understand the properties of branching morphologies we must study the differences between distinct arbor types.…”