Speaker and Award Recipient: Astrid Deryckere
Postdoctoral Research Fellow
Columbia University
Title: Developmental programs underlying layer formation in the vertebrate forebrain
Abstract: The central nervous system is one of the most complex organs, allowing organisms to execute daily tasks with astonishing accuracy. During vertebrate evolution, new neuron types have evolved in the brain, contributing to a general expansion of nervous system complexity, and ultimately behaviors. This expansion of neuron types originates from changes in the developmental program, where progenitor cells sequentially generate distinct neuron types. In the mammalian neocortex, these different types of neurons organize into 6 characteristic layers. Historically, the dorsal telencephalon or pallium of non-mammalian vertebrates has been described as extremely simple, without evidence of heterogeneity, especially along the radial axis. However, the use of modern molecular tools established the existence of layers in the pallia of species where layers cannot be recognized by traditional histology alone. In reptiles for example, the seemingly single layer of pyramidal neurons in the cortex is organized into two sublayers of molecularly distinct neuron types (Tosches et al 2018). In amphibians, where the pallium had never been considered "layered", cell type analysis shows the existence of two layers of neurons with distinct transcriptomes (Woych et al 2022), indicating that layering of neuron types is ancestral in tetrapods.
To generate new insights on the evolution of a layered cortex in the vertebrate brain, we investigate the development of neuronal diversity in the pallium of tetrapods. By studying the salamander Pleurodeles waltl, we discovered that the two molecularly distinct layers are generated sequentially over development, similar to what has been described in reptilian and mammalian cortices. To investigate whether the diversity of salamander and mammalian pallia correlates with differences in progenitor cells, we profiled the developing telencephalon of salamanders using single-cell RNA sequencing. We found that the diversity of salamander and mammalian radial glia progenitors over developmental time could be described by gradual changes in the expression of similar gene sets, including the same temporal transcription factors. We also identified a previously unknown progenitor state with cells expressing markers of mammalian intermediate progenitors. Our data suggest that the expansion of neuronal diversity in vertebrate brains might have arisen through changes of neuronal specification programs in post-mitotic neurons rather than in progenitors.
About the Charles H. Turner Award
Monday, June 10, 2024 - 12:00pm
601 Fairchild
Host: Oliver Hobert
