Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we will assume that you are happy to receive all cookies and you will not see this message again. Click 'Find out more' for information on how to change your cookie settings.

According to Fernando García-Moreno and Zoltán Molnár understanding development and evolution of the neocortex has important implications. Differential timing of developmental events sculpts the brains of different species into distinct organs. The latest investigations on the development of the dorsal forebrain in chick and mouse embryos showed a major difference between vertebrate brains. A delay in the neurogenic properties of a subset of progenitors is specific to mammals and could be responsible for the evolutionary origin of the corpus callosum...

PNAS Publication 1

Fernando García-Moreno and Zoltán Molnár publish a paper in PNAS, Subset of early radial glial progenitors that contribute to the development of callosal neurons is absent from avian brain, showing an interesting divergence of the embryonic development of the forebrain of vertebrate species.

The classical view of mammalian cortical development suggests that pyramidal neurons are generated in a temporal sequence, with all radial glial cells (RGCs) contributing to both lower and upper neocortical layers. A recent opposing proposal suggests there is a subgroup of fate-restricted RGCs in the early neocortex, which generates only upper-layer neurons. Little is known about the existence of fate restriction of homologous progenitors in other vertebrate species. We investigated the lineage of selected Emx2+ [vertebrate homeobox gene related to Drosophila empty spiracles (ems)] RGCs in mouse neocortex and chick forebrain and found evidence for both sequential and fate-restricted programs only in mouse, indicating that these complementary populations coexist in the developing mammalian but not avian brain. Among a large population of sequentially programmed RGCs in the mouse brain, a subset of self-renewing progenitors lack neurogenic potential during the earliest phase of corticogenesis. After a considerable delay, these progenitors generate callosal upper-layer neurons and glia. On the other hand, we found no homologous delayed population in any sectors of the chick forebrain. This finding suggests that neurogenic delay of selected RGCs may be unique to mammals and possibly associated with the evolution of the corpus callosum.

 

FIGURE: Mammalian but not avian forebrain stem/progenitor cells labelled through Emx2 promoter sequence show delayed neurogenesis.
Top row - Examples of the distribution of the cortical neurons in mouse E14, 2 days after electroporation with general and Emx2 promoter construct at E12.
Bottom row - Chick cases at E6, 2 days after electroporation at E4.
Left column - Labelled with EGFP, early progenitors of the forebrain generated neurons that migrated to the postmitotic areas (CP: cortical plate; MZ: mantle zone).
Right column - Also labelled with EGFP, early progenitors selected by their expression of Emx2 did not generate neurons in mouse (observe the absence of green cells in CP) but were neurogenic in chick (green cells were present in MZ).

 

More info on the PNAS website.

Stem cells with delayed neurogenesis and the evolution of callosal interhemispheric connections in the mammalian brain, Article on the Human Frontier Science Program website.

Similar stories

Continued ethical animal research needed to advance treatment of brain disease, researchers argue

More research is needed to improve the treatment of brain diseases such as depression, Alzheimer’s or ADHD. A widely held view within the scientific community is that this cannot be done without ethically conducted animal research. A team of seventy international neuroscientists, including DPAG’s Associate Professor Vladyslav Vyazovskiy, have now published a warning that animal research is under pressure, which endangers the further development of treatments.

Cortex may regulate the need for sleep

Why we sleep, and the processes behind sleep, are amongst the most interesting questions in modern neuroscience. Researchers at the University of Oxford, including DPAG's Molnár and Vyazovskiy group scientists, have now uncovered a new target for sleep investigations within the mammalian brain – the cerebral cortex. The paper, first authored by Dr Lukas Krone, was published today in Nature Neuroscience.

Reducing fat in the diabetic heart could improve recovery from heart attack

New research from the Heather Group has shown that in type 2 diabetes an overload of lipids reduces the heart’s ability to generate energy during a heart attack, decreasing chances of recovery.

The brain’s one-sided teaching signals

A new study by the Lak group reveals a novel facet of dopamine signalling during visual decision making.

Fellowship awarded to Huriye Atilgan to enhance our understanding of value-based decision-making

Congratulations are in order for Postdoctoral Research Scientist Dr Huriye Atilgan who has been awarded a prestigious Sir Henry Wellcome Postdoctoral Fellowship funded by the Wellcome Trust.