Dendritic allometry of neocortical pyramidal neurons across mammalian brain size

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• Picked for Histology (top studies of the week, 8 November 2026): Quantitative neuronal morphology links dendritic structure with brain size

Abstract

Neuron number increases with mammalian brain size, but how the dendritic morphology of individual neocortical pyramidal neurons changes across this range remains unclear. To address this question, we examined 2,412 neocortical pyramidal neuron reconstructions from 23 mammalian species in NeuroMorpho.Org, spanning an approximately 11,000-fold range in brain weight. At the whole-neuron level, primary axis length, lateral extent, and Sholl critical radius increased with brain size but remained far below the isometric expectation, whereas total dendritic length showed no significant association. Mean remote bifurcation angle, section tortuosity, and maximum branch order decreased with brain size, suggesting that greater spatial reach was accompanied by a more streamlined arbor organization rather than by proportional increases in dendritic cable length or branching depth. Compartment-resolved analyses localized much of the spatial, cable-length, and fixed-radius Sholl signal to basal dendrites, whereas apical spatial expansion was weaker. By contrast, branch geometry associations were broadly similar between apical and basal compartments. Together, these patterns suggest that mammalian pyramidal neuron morphology varies with brain size through selective spatial expansion and basal-dominant compartmental scaling rather than through uniform enlargement of individual arbors.

Abstract as published, via PubMed.