ArticleProceedings of the National Academy of Sciences of the United States of America2018
A pan-mammalian map of interhemispheric brain connections predates the evolution of the corpus callosum.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 42 papers.
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42 citing papers in PubMed, 83 citations in OpenAlex.
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- A population of Insula neurons encodes for social preference only after acute social isolation in mice.Nature communications · 2024Article
- Direct interhemispheric cortical communication via thalamic commissures: a new white matter pathway in the primate brain.Cerebral cortex (New York, N.Y. : 1991) · 2024Article
- Development and Evolution of Thalamocortical Connectivity.Cold Spring Harbor perspectives in biology · 2024Review
- Variation and convergence in the morpho-functional properties of the mammalian neocortex.Frontiers in systems neuroscience · 2024Review
- Brain asymmetry is globally different in males and females: exploring cortical volume, area, thickness, and mean curvature.Cerebral cortex (New York, N.Y. : 1991) · 2023Article
- Non-uniform temporal scaling of developmental processes in the mammalian cortex.Nature communications · 2023Article
- Clade-specific forebrain cytoarchitectures of the extinct Tasmanian tiger.Proceedings of the National Academy of Sciences of the United States of America · 2023Article
- Cortical activity emerges in region-specific patterns during early brain development.Proceedings of the National Academy of Sciences of the United States of America · 2023Article
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- Expression of SATB1 and SATB2 in the brain of bony fishes: what fish reveal about evolution.Brain structure & function · 2023Article
- Cortical activity emerges in region-specific patterns during early brain development.bioRxiv : the preprint server for biology · 2023Article
- The relevance of heterotopic callosal fibers to interhemispheric connectivity of the mammalian brain.Cerebral cortex (New York, N.Y. : 1991) · 2023Article
- Regional and cell-type-specific afferent and efferent projections of the mouse claustrum.Cell reports · 2023Article
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7 authors at 1 institution in 1 country.
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No grant is acknowledged in the PubMed record.
Abstract
The brain of mammals differs from that of all other vertebrates, in having a six-layered neocortex that is extensively interconnected within and between hemispheres. Interhemispheric connections are conveyed through the anterior commissure in egg-laying monotremes and marsupials, whereas eutherians evolved a separate commissural tract, the corpus callosum. Although the pattern of interhemispheric connectivity via the corpus callosum is broadly shared across eutherian species, it is not known whether this pattern arose as a consequence of callosal evolution or instead corresponds to a more ancient feature of mammalian brain organization. Here we show that, despite cortical axons using an ancestral commissural route, monotremes and marsupials share features of interhemispheric connectivity with eutherians that likely predate the origin of the corpus callosum. Based on ex vivo magnetic resonance imaging and tractography, we found that connections through the anterior commissure in both fat-tailed dunnarts (Marsupialia) and duck-billed platypus (Monotremata) are spatially segregated according to cortical area topography. Moreover, cell-resolution retrograde and anterograde interhemispheric circuit mapping in dunnarts revealed several features shared with callosal circuits of eutherians. These include the layered organization of commissural neurons and terminals, a broad map of connections between similar (homotopic) regions of each hemisphere, and regions connected to different areas (heterotopic), including hyperconnected hubs along the medial and lateral borders of the cortex, such as the cingulate/motor cortex and claustrum/insula. We therefore propose that an interhemispheric connectome originated in early mammalian ancestors, predating the evolution of the corpus callosum. Because these features have been conserved throughout mammalian evolution, they likely represent key aspects of neocortical organization.
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