Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled‐up primate brain

  title={Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled‐up primate brain},
  author={Frederico A. C. Azevedo and Ludmila R.B. Carvalho and Lea Tenenholz Grinberg and Jos{\'e} Marcelo Farfel and Renata E. L. Ferretti and Renata Elaine Paraizo Leite and Wilson Jacob Filho and Roberto Lent and Suzana Herculano‐Houzel},
  journal={Journal of Comparative Neurology},
The human brain is often considered to be the most cognitively capable among mammalian brains and to be much larger than expected for a mammal of our body size. [] Key Method Here we determine these numbers by using the isotropic fractionator and compare them with the expected values for a human-sized primate. We find that the adult male human brain contains on average 86.1 +/- 8.1 billion NeuN-positive cells ("neurons") and 84.6 +/- 9.8 billion NeuN-negative ("nonneuronal") cells. With only 19% of all…
The Human Brain in Numbers: A Linearly Scaled-up Primate Brain
These studies showed that the human brain is not exceptional in its cellular composition, as it was found to contain as many neuronal and non-neuronal cells as would be expected of a primate brain of its size, and argue in favor of a view of cognitive abilities that is centered on absolute numbers of neurons.
The remarkable, yet not extraordinary, human brain as a scaled-up primate brain and its associated cost
It is argued that the human brain is a scaled-up primate brain in its cellular composition and metabolic cost, with a relatively enlarged cerebral cortex that does not have a relatively larger number of brain neurons yet is remarkable in its cognitive abilities and metabolism simply because of its extremely large number of neurons.
What Makes the Human Brain Special: Key Features of Brain and Neocortex
It is suggested that cognitive functions are largely mediated by the neocortex, and because the human brain scales like a typical primate brain, the large neocortex of humans contains more neurons than any other mammal, even those with larger brains such as elephants.
All brains are made of this: a fundamental building block of brain matter with matching neuronal and glial masses
It is proposed that there is a fundamental building block of brain tissue: the glial mass that accompanies a unit of neuronal mass, which is a consequence of a universal mechanism whereby numbers of glial cells are added to the neuronal parenchyma during development, irrespective of whether the neurons composing it are large or small.
The elephant brain in numbers
The hypothesis that the larger absolute number of neurons in the human cerebral cortex (but not in the whole brain) is correlated with the superior cognitive abilities of humans compared to elephants and other large-brained mammals is supported.
The search for true numbers of neurons and glial cells in the human brain: A review of 150 years of cell counting
A survey of original evidence shows that histological data always supported a 1:1 ratio of glia to neurons in the entire human brain, and a range of 40–130 billion glial cells, and the current status of knowledge about the number of cells is reviewed.
Faster Scaling of Auditory Neurons in Cortical Areas Relative to Subcortical Structures in Primate Brains
The scaling of brain structures in the auditory pathway of six primate species and the closely related tree shrew is investigated and each auditory structure scales in mass as a linear function of its number of neurons, with no significant changes in neuronal density across species.
Brains matter, bodies maybe not: the case for examining neuron numbers irrespective of body size
It is proposed that the absolute number of neurons, irrespective of brain or body size, is a better predictor of cognitive ability—in which case, the cognitive superiority of humans would come as no paradox, surprise, or exception to evolutionary rules.
Cellular Scaling Rules for the Brains of an Extended Number of Primate Species
It is described that the cellular composition of the same brain structures of 5 other primate species, as well as humans, conform to the scaling rules identified previously, and that the updated power functions for the extended sample are similar to those determined earlier.
Stereological estimation of total cell numbers in the human cerebral and cerebellar cortex
Normal brain development in humans and age related changes in terms of cell numbers are focused on, and for comparative purposes a few examples of neocortical neuron number in other mammals are presented.


Cellular scaling rules for rodent brains
It is proposed that the faster increase in average neuronal size in the cerebral cortex than in the cerebellum as these structures gain neurons and the rapidly increasing glial numbers that generate glial mass to match total neuronal mass at a fixed glia/neuron total mass ratio are fundamental cellular constraints that lead to the relative expansion of cerebral cortical volume across species.
Neocortical neuron number in humans: Effect of sex and age
Sex and age were the main determinants of the total number of neurons in the human neocortex, whereas body size, per se, had no influence on neuron number.
Evolution of increased glia–neuron ratios in the human frontal cortex
Analysis of glia–neuron ratios across frontal areas 4, 9L, 32, and 44 in a sample of humans, chimpanzees, and macaque monkeys showed that regions involved in specialized human cognitive functions have not evolved differentially higher requirements for metabolic support.
Cellular scaling rules for primate brains
The cellular scaling rules for primate brains are examined and it is shown that brain size increases approximately isometrically as a function of cell numbers, such that an 11× larger brain is built with 10× more neurons and ≈12× more nonneuronal cells of relatively constant average size.
Isotropic Fractionator: A Simple, Rapid Method for the Quantification of Total Cell and Neuron Numbers in the Brain
A novel, fast, and inexpensive method to quantify total numbers of neuronal and non-neuronal cells in the brain or any dissectable regions thereof, which consists of transforming highly anisotropic brain structures into homogeneous, isotropic suspensions of cell nuclei, which can be counted and identified immunocytochemically as neuronal or non-NEuronal.
Neocortical glial cell numbers in human brains
A quantitative study of the human cerebellum with unbiased stereological techniques
Estimates of total number of different neuron and glial cell types in the dentate nuclei and the four major regions of the human cerebellum were obtained by new stereological methods. With the
Humans and great apes share a large frontal cortex
It is suggested that the special cognitive abilities attributed to a frontal advantage may be due to differences in individual cortical areas and to a richer interconnectivity, none of which required an increase in the overall relative size of the frontal lobe during hominid evolution.
Evolution of the brain and intelligence
Prefrontal cortex in humans and apes: a comparative study of area 10.
The human brain is larger relative to the rest of the brain than it is in the apes, and its supragranular layers have more space available for connections with other higher-order association areas, which suggests that the neural substrates supporting cognitive functions associated with this part of the cortex enlarged and became specialized during hominid evolution.