Dendritic architecture of rat somatosensory thalamocortical projection neurons

Abstract

This study examines dendrites from physiologically characterized and intracellularly labelled thalamocortical projection (TCP) neurons from the rat ventrobasal complex (VB) and posterior nucleus (POm). The goals were to provide quantitative descriptions of TCP neuron dendrites, examine underlying design principles of dendritic morphology, and determine correlations between dendritic size parameters. Forty-four dendrites from seven VB neurons and 21 dendrites from three POm TCP neurons that responded to low-threshold mechanical stimuli were reconstructed and quantitatively analyzed at the light microscopic level. The dendritic architecture of the neurons was remarkably similar in most parameters studied, including the percentage of dichotomous branching, contribution of terminal branches to total dendritic length, and branching symmetry. There was a positive correlation between stem dendrite diameter and the length of the entire dendrite arbor, making it possible to estimate the total length of a dendritic arbor by measuring the stem dendrite diameter. The correlations of the VB and POm dendrites had different slopes. The path distance (the distance from the soma to a dendritic end point) of individual dendrites showed only a small variation with large differences in the total dendritic length of an arbor. The constant diameter of distal dendrites shows that dendrite diameter is a poor predictor of synaptic location on the dendritic tree. Although the morphology of neurons and their individual dendrites varied considerably in overall size and qualitative appearance, when examined qualitatively, many aspects of dendritic structure were similar within and between groups. We suggest that the rat somatosensory TCP neurons have a stereotyped dendritic architecture and present data which provide a base for future comparative, developmental, and plasticity studies.

Effects of GSM 1800 MHz on dendritic development of cultured hippo-campal neurons

“…The alterations of dendritic growth and development induced by GSM microwave treatment may be associated with the changes in cytoskeleton-related molecules, such as actin and microtubule-associated protein-2 (MAP-2). Mobile phone radiation was found to affect the stability of F-actin stress fibers [37] and increase the expression of the F-actin in human endothelial cells [38,39] . The expression of MAP-2 in hippocampal neurons was reported to decrease after sustained exposure to static magnetic fields [40] .…”

NMDA Receptor-Dependent Regulation of Axonal and Dendritic Branching

“…Images of neurons were then scanned at 300 dots per inch and standardized and stored in Adobe Photoshop 7.0 (Adobe Systems, San Jose, CA). In this study, we adopted the terminology used by Ohara and Havton (1994). The dendrite derived directly from the soma is the first-order branch or primary dendrite.…”

Dendroarchitecture and Lateral Inhibition in Thalamic Barreloids

“…Thus, within the range of background discharges used to test inhibition (15-25 Hz), data points are best fitted by linear regression with R 2 ϭ 0.86 ( p Ͻ 0.0001). Because distal dendrites exhibit little tapering (Ohara and Havton, 1994;Varga et al, 2002), using dendritic surface areas instead of dendritic lengths did not significantly alter the linear relationship.…”

“…Only in the ventral posterior medial nucleus (VPM) of the thalamus do we know which neurons are involved and their connections. The VPM of rodents contains a single class of neurons, the relay cells (Barbaresi et al, 1986;Harris, 1986;Ohara and Havton, 1994), which are clustered within whisker-related aggregates termed barreloids. Each barreloid contains neurons that respond strongly to the motion of one vibrissa, the principal whisker (PW), and more weakly to that of one to four adjacent whiskers (AWs) (Simons and Carvell, 1989;Armstrong-James and Callahan, 1991;Chiaia et al, 1991;Diamond et al, 1992;Friedberg et al, 1999;.…”