Prefrontal white matter volume is disproportionately larger in humans than in other primates

Schoenemann, P. Thomas; Sheehan, Michael J.; Glotzer, L Daniel

doi:10.1038/nn1394

Cited by 348 publications

(301 citation statements)

References 36 publications

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“…The extensive scope of myelination is the single-most unique aspect in which the human brain differs from that of other species [1][2][3]. In this myelin model of human evolution and development, our brain's extensive myelination accounts for the high processing speeds and precise temporal coding underlying higher cognitive and behavioral functions [4,5].…”

Section: Introductionmentioning

confidence: 99%

Human brain myelination and amyloid beta deposition in Alzheimer's disease

Bartzokis

Mintz

2007

Alzheimer's & Dementia

136

138

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We hypothesized that myelin breakdown in vulnerable late-myelinating regions releases oligodendrocyte-and myelin-associated iron that promotes amyloid beta (Aβ) oligomerization, its associated toxicity, and the deposition of oligomerized Aβ and iron in neuritic plaques observed in Alzheimer's disease (AD). The model was tested by using published maps of cortical myelination from 1901 and recent in vivo imaging maps of Aβ deposits in humans. The data show that in AD, radiolabeled ligands detect Aβ deposition in a distribution that matches the map of late-myelinating regions. Furthermore, the strikingly lower ability of this imaging ligand to bind Aβ in animal models is consistent with the much lower levels of myelin and associated iron levels in rodents when compared with humans. The hypotheses derived from the "myelin model" are testable with current imaging methods and have important implications for therapeutic interventions that should be expanded to include novel targets such as oligodendrocytes, myelin, and brain iron.

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Section: Introductionmentioning

confidence: 99%

Human brain myelination and amyloid beta deposition in Alzheimer's disease

Bartzokis

Mintz

2007

Alzheimer's & Dementia

136

138

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“…specialized for frontal cortex functions, as opposed to functions mediated by more extended networks, requires scaling to be taken into account. Here we test the hypothesis that human frontal cortex and prefrontal cortex (PFC) size is larger than expected from scaling against other brain structures, an empirical issue that is still contested (4,6,(8)(9)(10).…”

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confidence: 99%

“…Early claims (1, 2) have been both cited as evidence for relative expansion (3,4) and questioned owing to small sample sizes and uncertainty about anatomical boundaries defined using older methods (5,6).…”

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confidence: 99%

“…Newer and larger data sets have not yet resolved these uncertainties but have been used as support for the claim of disproportionate expansion of frontal lobe structures and specific tissue types (4,(6)(7)(8)(9)(10), for the lack of thereof (5,10,11), or have given ambiguous results depending on factors such as which species are included in the analysis (12). In addition, there is variability among these studies as to whether and which other ape species are reported to exhibit similar relative expansion as humans (5,6,9).…”

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confidence: 99%

“…In addition, there is variability among these studies as to whether and which other ape species are reported to exhibit similar relative expansion as humans (5,6,9). Finally, among those studies reporting larger than expected values for humans and/or other apes, there is little consistency in terms of which measures show differences, with claims based variously on whole frontal cortex volume (5), volume of prefrontal area 10 (7), prefrontal vs. nonprefrontal white matter volume (6), and left (but not right) prefrontal white matter volume relative to prefrontal gray matter volume (9).…”

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confidence: 99%

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Human frontal lobes are not relatively large

Barton

Venditti

2013

Proc. Natl. Acad. Sci. U.S.A.

138

114

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One of the most pervasive assumptions about human brain evolution is that it involved relative enlargement of the frontal lobes. We show that this assumption is without foundation. Analysis of five independent data sets using correctly scaled measures and phylogenetic methods reveals that the size of human frontal lobes, and of specific frontal regions, is as expected relative to the size of other brain structures. Recent claims for relative enlargement of human frontal white matter volume, and for relative enlargement shared by all great apes, seem to be mistaken. Furthermore, using a recently developed method for detecting shifts in evolutionary rates, we find that the rate of change in relative frontal cortex volume along the phylogenetic branch leading to humans was unremarkable and that other branches showed significantly faster rates of change. Although absolute and proportional frontal region size increased rapidly in humans, this change was tightly correlated with corresponding size increases in other areas and whole brain size, and with decreases in frontal neuron densities. The search for the neural basis of human cognitive uniqueness should therefore focus less on the frontal lobes in isolation and more on distributed neural networks.

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