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We study the distribution of brain and cortical area sizes [parcellation units (PUs)] obtained for three species: mouse, macaque, and human. We find that the distribution of PU sizes is close to lognormal. We propose the mathematical model of evolution of brain parcellation based on iterative fragmentation and specialization. In this model, each existing PU has a probability to be split that depends on PU size only. This model suggests that the same evolutionary process may have led to brain parcellation in these three species. Within our model, region-to-region (macro) connectivity is given by the outer product form. We show that most experimental data on non-zero macaque cortex macroscopic-level connections can be explained by the outer product power-law form suggested by our model (62% for area V1). We propose a multiplicative Hebbian learning rule for the macroconnectome that could yield the correct scaling of connection strengths between areas. We thus propose an evolutionary model that may have contributed to both brain parcellation and mesoscopic level connectivity in mammals.
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http://dx.doi.org/10.3389/fncir.2016.00043 | DOI Listing |
Background Neurocognitive impairment (NCI) is a common comorbidity among aging people with HIV (PWH), despite effective antiretroviral therapy (ART). Processing speed is often the earliest affected cognitive domain and may be linked to disrupted functional brain network organization. This study investigated whether the balance of segregation and integration in large-scale functional networks is associated with processing speed in middle-aged and older PWH.
View Article and Find Full Text PDFUnlabelled: In magnetic resonance imaging, graph signal processing (GSP) is an analytical framework that enables to express regional functional activity time courses in terms of the underlying structural connectivity backbone. To this end, several parameters must be set during the processing of structural and functional data, and a variety of output features have been proposed. While emerging applications of the GSP framework have shown clear merits to reveal the neural underpinnings of brain disorders, behavioural facets or individuality, at present, the optimal parameter choices and feature types for an outcome of interest remain unknown.
View Article and Find Full Text PDFDev Cogn Neurosci
August 2025
Université Paris Cité, Inserm, NeuroDiderot, Paris F-75019, France; Université Paris-Saclay, CEA, NeuroSpin, UNIACT, Gif-sur-Yvette F-91191, France.
The sensorimotor system develops early in utero and supports the emergence of body representations critical for perception, action, and interaction with environment. While somatotopic protomaps are already developed in the primary somatosensory and motor cortices in late pregnancy, little is known about the anatomical substrates of this functional specialization. In this study, we aimed to decipher the microstructural properties of these regions in the developing brain.
View Article and Find Full Text PDFNeuroimage
September 2025
University of Electronic Science and Technology of China, Chengdu, China. Electronic address:
Brain nuclei are clusters of anatomically distinct neurons that serve as important hubs for processing and relaying information in various neural circuits. Fine-scale parcellation of the brain nuclei is vital for a comprehensive understanding of their anatomico-functional correlations. Diffusion MRI tractography is an advanced imaging technique that can estimate the brain's white matter structural connectivity to potentially reveal the topography of the nuclei of interest for studying their subdivisions.
View Article and Find Full Text PDFArXiv
August 2025
University of California Irvine, Department of Radiological Sciences, Irvine, CA 92617, USA.
Accurate characterization of in-utero brain development is essential for understanding typical and atypical neurodevelopment. Building upon previous efforts to construct spatiotemporal fetal brain MRI atlases, we present the CRL-2025 fetal brain atlas, which is a spatiotemporal (4D) atlas of the developing fetal brain between 21 and 37 gestational weeks. This atlas is constructed from carefully processed MRI scans of 160 fetuses with typically-developing brains using a diffeomorphic deformable registration framework integrated with kernel regression on age.
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