Pyramidal cells in prefrontal cortex of primates: marked differences in neuronal structure among species.

Alejandra Elston Elston

doi:10.3389/fnana.2011.00002

Abstract

The most ubiquitous neuron in the cerebral cortex, the pyramidal cell, is characterized by markedly different dendritic structure among different cortical areas. The complex pyramidal cell phenotype in granular prefrontal cortex (gPFC) of higher primates endows specific biophysical properties and patterns of connectivity, which differ from those in other cortical regions. However, within the gPFC, data have been sampled from only a select few cortical areas. The gPFC of species such as human and macaque monkey includes more than 10 cortical areas. It remains unknown as to what degree pyramidal cell structure may vary among these cortical areas. Here we undertook a survey of pyramidal cells in the dorsolateral, medial, and orbital gPFC of cercopithecid primates. We found marked heterogeneity in pyramidal cell structure within and between these regions. Moreover, trends for gradients in neuronal complexity varied among species. As the structure of neurons determines their computational abilities, memory storage capacity and connectivity, we propose that these specializations in the pyramidal cell phenotype are an important determinant of species-specific executive cortical functions in primates.

Highlights

Pyramidal cell structure is remarkably heterogeneous in the primate cerebral cortex
Estimates of the total number of spines in the dendritic trees of pyramidal cells reveal more than a 30-fold difference between populations of cells sampled in different cortical areas (Elston et al, 2001, 2005c)
The basal dendrites have a diameter smaller than the neck length of many spines, and any possible error that may arise because some populations of cells have thicker basal dendrites than others would only reduce the extent of differences we report for cells among cortical areas

Summary

Introduction

Pyramidal cell structure is remarkably heterogeneous in the primate cerebral cortex. Estimates of the total number of spines (putative excitatory inputs) in the dendritic trees of pyramidal cells reveal more than a 30-fold difference between populations of cells sampled in different cortical areas (Elston et al, 2001, 2005c). Complexity in dendritic structure determines their biophysical properties influencing their functional capacity and potential for plastic changes (Koch, 1999; Mel, 1999; Jan and Jan, 2001; Chklovskii et al, 2004; London and Häusser, 2005) These specializations in neuron structure in the gPFC are thought to subserve executive functions (Funahashi and Kubota, 1994; Courtney et al, 1998; Duncan and Owen, 2000; Goldman-Rakic, 2000; Miller, 2000; Rolls, 2000; Fuster, 2001; Wang, 2001; Treves, 2005); pyramidal cell structure has been quantified in only few of the many cortical areas within gPFC

Objectives

Methods

Results

Discussion

Conclusion