About this Research Topic
Cajal’s seminal work launched the exploration of the brain using distinct morphological characters to categorize neurons and relate morphology to function. Since then, our definition of distinct cell types has deepened, including different features that we now have access to. A) The developmental history of different neuronal types and their lineage relationships offered the possibility to link developmental programs with neuronal circuits and the functions they support, providing a biological basis for classification. B) The evolutionary history of different neuronal types has also been used to define the boundaries of a cell type. C) Lately, the explosion in single-cell analyses have allowed us to incorporate high-throughput transcriptional, epigenetic, proteomic, and physiological signatures in a cell type’s repertoire and expand the parameter space in feature-function correspondence.
Classification of cells into types serves the important need to categorize information. With the detailed description of molecular identity added on top of morphology, function, development and evolution, the boundaries between cell types can be either more defined or more blurred: different perspectives do not necessarily converge in their classification. Recent advances in single cell profiling have expanded the number of axes by which cellular identities can be defined. How can this diverse information be reconciled to define a cell type? Importantly, is there such a thing as a discrete cell type or does such a classification partition arbitrarily what is in fact a biological continuum?
By addressing the importance of molecular features, development, evolution and physiology in neural categorization in different neuronal tissues and organisms, we can recommend a biologically justified definition of a cell type, establishing a fundamental conceptual framework for future studies.
The goal of this Research Topic is to study how neuronal types can be defined in different neuronal systems under distinct perspectives, ranging from morphology to molecular identity and physiology. We will collect Original Research, Review, Brief Research Report, Mini-Review articles that cover, but are not limited to the following subtopics:
- Neurogenesis and neural fate: neuronal fate specification, developmental trajectory, and neural identity.
- Lineage and neural identity/circuit: what is the relationship between lineage, neuronal identity and circuit formation?
- Evolution of cell types: how can we use evolutionary history to define cell types and understand the constraints limiting neuronal and circuit formation?
- Maintenance of neuronal identity: once a neuron commits to a specific neuronal identity, can it change? If not, how is neuronal identity maintained?
- Forced induction of neuronal identity: is there sufficient knowledge of key drivers of neuronal identity which can be used for direct lineage reprogramming into induced neurons?
- Determinism and randomness in cell type specification: what is the role of deterministic and stochastic events in the development and definition of neuronal identities?
- Cell types: discrete entities or continuum? How is plasticity contemplated in the definition of a cell type?
Keywords: Neuronal cell type, neural development, evolution, single-cell genomics, neuronal reprogramming
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.