The Dendritic Density Field of a Cortical Pyramidal Cell

Hermann Cuntz

doi:10.3389/fnana.2012.00002

Abstract

Much is known about the computation in individual neurons in the cortical column. Also, the selective connectivity between many cortical neuron types has been studied in great detail. However, due to the complexity of this microcircuitry its functional role within the cortical column remains a mystery. Some of the wiring behavior between neurons can be interpreted directly from their particular dendritic and axonal shapes. Here, I describe the dendritic density field (DDF) as one key element that remains to be better understood. I sketch an approach to relate DDFs in general to their underlying potential connectivity schemes. As an example, I show how the characteristic shape of a cortical pyramidal cell appears as a direct consequence of connecting inputs arranged in two separate parallel layers.

Highlights

The laws of time, space, and material conservation, which must be considered the final cause of all variations in the shape of neurons, should in our view be immediately obvious to anyone thinking about or trying to verify them, and ought to constitute the final proof of our axopetal polarity theory
Physiological analyses in combination with anatomical characterizations of the individual neurons involved were successful in unraveling many details of local cortical connectivity (e.g., Szentágothai, 1975; Douglas and Martin, 2004; Lübke and Feldmeyer, 2007)
Evidence exists that neurons send out their dendrites to allow potential connections to the axons of all neurons of their particular target neuron types within their column (Lübke et al, 2003; Douglas and Martin, 2004; Kalisman et al, 2005)

Summary

The dendritic density field of a cortical pyramidal cell

Reviewed by: Armen Stepanyants, Northeastern University, USA Guy Elston, International Brain Research Organization, Switzerland. Evidence exists that neurons send out their dendrites to allow potential connections (points of anatomical proximity; Stepanyants and Chklovskii, 2005) to the axons of all neurons of their particular target neuron types within their column (Lübke et al, 2003; Douglas and Martin, 2004; Kalisman et al, 2005). In order to simulate anatomical connections between neurons, model assumptions for both dendrite and axon morphologies are required. One approach is to estimate synaptic connectivity based on anatomical neuron models obtained from neuron reconstructions (Lübke et al, 2003; Douglas and Martin, 2004; Fares and Stepanyants, 2009) or by simulating the mechanisms of dendrite and axon growth (Koene et al, 2009; van Pelt et al, 2010). THE DENDRITIC DENSITY FIELD AND MORPHOLOGICAL MODELING We have shown previously that by extending the minimum spanning tree (MST) algorithm it is possible to connect a set of point

Dendritic density fields

METHODS