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Frederico A. C. Azevedo

Bio: Frederico A. C. Azevedo is an academic researcher from Max Planck Society. The author has contributed to research in topics: Auditory cortex & Auditory area. The author has an hindex of 6, co-authored 7 publications receiving 2080 citations. Previous affiliations of Frederico A. C. Azevedo include University of Tübingen & Federal University of Rio de Janeiro.

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Journal ArticleDOI
TL;DR: The findings challenge the common view that humans stand out from other primates in their brain composition and indicate that, with regard to numbers of neuronal and nonneuronal cells, the human brain is an isometrically scaled‐up primate brain.
Abstract: 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. Although the number of neurons is generally assumed to be a determinant of computational power, and despite the widespread quotes that the human brain contains 100 billion neurons and ten times more glial cells, the absolute number of neurons and glial cells in the human brain remains unknown. 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 neurons located in the cerebral cortex, greater cortical size (representing 82% of total brain mass) in humans compared with other primates does not reflect an increased relative number of cortical neurons. The ratios between glial cells and neurons in the human brain structures are similar to those found in other primates, and their numbers of cells match those expected for a primate of human proportions. These findings challenge the common view that humans stand out from other primates in their brain composition and indicate that, with regard to numbers of neuronal and nonneuronal cells, the human brain is an isometrically scaled-up primate brain.

1,818 citations

Journal ArticleDOI
TL;DR: It is demonstrated that species-specific vocalizations in rhesus monkeys activate preferentially the auditory ventral stream, and in particular areas of the antero-lateral belt and parabelt.
Abstract: Using functional magnetic resonance imaging in awake behaving monkeys we investigated how species-specific vocalizations are represented in auditory and auditory-related regions of the macaque brain. We found clusters of active voxels along the ascending auditory pathway that responded to various types of complex sounds: inferior colliculus (IC), medial geniculate nucleus (MGN), auditory core, belt, and parabelt cortex, and other parts of the superior temporal gyrus (STG) and sulcus (STS). Regions sensitive to monkey calls were most prevalent in the anterior STG, but some clusters were also found in frontal and parietal cortex on the basis of comparisons between responses to calls and environmental sounds. Surprisingly, we found that spectrotemporal control sounds derived from the monkey calls (“scrambled calls”) also activated the parietal and frontal regions. Taken together, our results demonstrate that species-specific vocalizations in rhesus monkeys activate preferentially the auditory ventral stream, and in particular areas of the antero-lateral belt and parabelt.

304 citations

Journal ArticleDOI
TL;DR: These four dogmas, which claim that the cerebral cortex is the pinnacle of brain evolution, are examined and challenged, and other interpretations or simply their replacement with alternative views are proposed.
Abstract: Owing to methodological shortcomings and a certain conservatism that consolidates wrong assumptions in the literature, some dogmas have become established and reproduced in papers and textbooks, derived from quantitative features of the brain. The first dogma states that the cerebral cortex is the pinnacle of brain evolution – based on the observations that its volume is greater in more ‘intelligent’ species, and that cortical surface area grows more than any other brain region, to reach the largest proportion in higher primates and humans. The second dogma claims that the human brain contains 100 billion neurons, plus 10-fold more glial cells. These round numbers have become widely adopted, although data provided by different authors have led to a broad range of 75–125 billion neurons in the whole brain. The third dogma derives from the second, and states that our brain is structurally special, an outlier as compared with other primates. Being so large and convoluted, it is a special construct of nature, unrelated to evolutionary scaling. Finally, the fourth dogma appeared as a tentative explanation for the considerable growth of the brain throughout development and evolution – being modular in structure, the brain (and particularly the cerebral cortex) grows by tangential addition of modules that are uniform in neuronal composition. In this review, we sought to examine and challenge these four dogmas, and propose other interpretations or simply their replacement with alternative views.

157 citations

Journal ArticleDOI
22 Feb 2017-Neuron
TL;DR: FMRI data indicates that space is predominantly represented by a distributed hemifield code rather than by a local spatial topography, and suggests that enhanced posterior-dorsal spatial specificity in primates might emerge from this form of coding.

51 citations

Journal ArticleDOI
TL;DR: A machine to automateIsotropic fractionation is developed, and its efficiency, consistency, and reliability as compared with manual processing are tested, concluding that the machine is more efficient because it utilizes many homogenizers simultaneously, equally consistent in producing high quality material for counting, and quantitatively reliable.

13 citations


Cited by
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06 Jun 1986-JAMA
TL;DR: The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or her own research.
Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

7,563 citations

Journal ArticleDOI
TL;DR: Progress made during the first half of the Human Connectome Project project in refining the methods for data acquisition and analysis provides grounds for optimism that the HCP datasets and associated methods and software will become increasingly valuable resources for characterizing human brain connectivity and function, their relationship to behavior, and their heritability and genetic underpinnings.

4,388 citations

Journal ArticleDOI
TL;DR: This analysis updates the widely-cited 10:1 ratio, showing that the number of bacteria in the body is actually of the same order as the numberof human cells, and their total mass is about 0.2 kg.
Abstract: Reported values in the literature on the number of cells in the body differ by orders of magnitude and are very seldom supported by any measurements or calculations. Here, we integrate the most up-to-date information on the number of human and bacterial cells in the body. We estimate the total number of bacteria in the 70 kg "reference man" to be 3.8·1013. For human cells, we identify the dominant role of the hematopoietic lineage to the total count (≈90%) and revise past estimates to 3.0·1013 human cells. Our analysis also updates the widely-cited 10:1 ratio, showing that the number of bacteria in the body is actually of the same order as the number of human cells, and their total mass is about 0.2 kg.

3,166 citations

01 Jan 2006

3,012 citations