A Fast And Accurate Procedure For Deriving The Sholl Profile Neuroonal Morphology

Journal of Neuroscience Methods 163 (2007) 24–30

A fast and accurate procedure for deriving the Sholl profile in quantitative studies of neuronal morphology
Humberto Gutierrez ∗ , Alun M. Davies
School of Biosciences, Cardiff University, Museum Avenue, P.O. Box 911, Cardiff CF10 3US, Wales, United Kingdom Received 16 November 2006; received in revised form 3 February 2007; accepted 6 February2007

Abstract The growth and elaboration of neural processes underpins the establishment of neural architecture during development and is a key facet of neural plasticity throughout life. Sholl analysis is a valuable and widely used method for quantifying the extent and complexity of neural processes in the vicinity of the neuronal soma, such as the dendritic arbors of individual neurons invivo and neuritic arbors of individual neurons in vitro. It consists of tracing a series of concentric rings with regular radial increments centred in the neuronal soma and counting the number Xi of processes intersecting each ring. This is a laborious and time-consuming procedure that consequently can only be applied to relatively small numbers of neurons. We propose a simpler and accurate methodfor deriving exactly the same information based only on the relative position, with respect to the cell soma, of the bifurcation (Bi ) and terminal points (Ti ) of processes. By means of the iterative equation Xi = Xi−1 + Bi − Ti, it is possible to automatically reconstruct the complete pattern of intersections between neurites and the concentric rings. We compared our method with the conventionalSholl analysis and found that our simplified procedure is approximately five times faster permitting numerically larger samples to be analyzed. We further tested the sensitivity of our method of analysis by looking at the effect of preventing NF- B signaling on BDNF-dependent neuritic growth in sensory neurons. © 2007 Elsevier B.V. All rights reserved.
Keywords: Sholl analysis; Morphology;Dendritic arbor; Pyramidal neurons; Sensory neuron

1. Introduction The pattern of growth and elaboration of neural processes is critical for the establishment of a functional nervous system during development and is an integral feature of the changes in neural architecture that contribute to plasticity in the mature nervous system. Sholl analysis (Sholl, 1953) is a widely used method for quantifyingand graphically representing the characteristic morphology of neuritic arbors (Caserta et al., 1995; Duan et al., 2003; Pante et al., 2005; Gutierrez et al., 2004, 2005; Haas et al., 2006; Ip et al., 2002; Isaacs et al., 1998; Kheirandish et al., 2005; Libersat and Duch, 2002; Lowndes et al., 1990; Mizrah and Libersat, 2002; Neale et al., 1993; Ristanovic et al., 2006; Shi et al., 2004; Robinson andKolb, 1997; Spires et al., 2004; Wood et al., 2004; Zagrebelsky et al., 2005). In the basic procedure, the number of intersections of neuritic processes with rings of increasing radii centred in the cell soma are counted.

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Corresponding author. Tel.: +44 29 2087 51 76. E-mail address: gutierrezh@cf.ac.uk (H. Gutierrez).

The Sholl profile is obtained by plotting the number ofintersections versus the radial distance from the cell soma (Sholl, 1953; Fig. 1B). Whether manually or computer assisted, this is a timeconsuming procedure that consequently can only be applied to relatively small numerical samples of neurons. In the case of computer-assisted systems, this is due to strict requirements in the image quality needed for their automatic processing. This in turn requiresextensive editing or laborious separate tracing of neural processes in order to obtain the well-segmented, noisefree images needed. Here we describe a simpler method for deriving the same information based on fewer input data: the number of processes emerging from the cell soma and relative positions, with respect to the cell soma, of bifurcation points and process terminals (Fig. 1B). This results in a...