Human and Rat Neocortical Development
The Development of the Human Neocortex
This new book deals exclusively with humans and may be considered a sequel to our 1991 book on neocortical development in the rat (presented below). We used our extensive photographic library of human embryonic, fetal, and some neonate specimens along with the sparse classical literature on human neocortical development. Some important developmental events, like the partitioning of the stratified transitional field (STF, the old intermediate zone) into distinctive lamination patterns of interacting migrating neurons and incoming and outgoing axons, are presented in an expanded set of diagrams and illustrations. The STF was discovered in rats, and it is much more pronounced in humans. Please see the link below for a 2002 paper on the human STF that appeared in the Journal of Neurocytology. STF documentation photographs were illustrated in our 5-volume series, Atlas of Human Central Nervous System Development. This new book treats that topic, and many other new observations in a concentrated look at only the human neocortex. The greatest part of the book is a series of annotated illustrations showing early to late developmental events, beginning with the appearance of the neocortical neuroepithelium and ending with an extensive documentation of myelination sequences and the appearance of cortical gyri. The book concludes with a discussion of hypotheses and interpretations of neocortical circuitry development and introduces a novel concept about an anchoring system that establishes the depths of early fissures and gyri in the initially smooth cortex as it becomes transformed into the intricately folded mature cortex. For example, the illustrations below explain our hypothesis of an anchoring system (modified from Figure 80B, top and Figure 81, bottom) in the final part of the book.
The link below is the pdf file of the entire book containing over 200 pages; the file is nearly 25 MB because of the extensive photographs included. The Laboratory of Developmental Neurobiology is offering this as a free book to anyone who wishes to learn more about human neocortical development. Enjoy reading! Please use the contact page to let us know what you think of our interpretations.
The Development of the Rat Neocortex
We used a variety of methods to investigate neuronal birthdays, embryonic development and cell migration in the rat neocortex. All that was published in 1991 by Raven Press, Neocortical Development. That book is out of print and we have obtained permission to reproduce it on this website. Each chapter is available for PDF download. For some chapters, we have included larger copies of figures, and we have written reviews of post-1991 literature; these chapters have a long download time because of the larger graphic files (files 4, 7, 10 and 12 in the bottom list).
The photo series above shows the different levels we used to determine the time of origin of neurons in different parts of the neocortex with 3H-thymidine autoradiography (Chapter 3, Figure 3-6; pdf file #5, bottom list). L1-L5 are the levels from most anterior (1) to most posterior (5). The straight black bars separate different areas of the cortex: Ai-agranular insular, CG- cingulate, FR-frontal, GU-gustatory, OCL-lateral occipital, OCM-medial occipital, PAR-parietal, PR-perirhinal, RS-retrosplenial, TE-temporal. The dashed lines indicate dorsomedial (DM), dorsolateral (DL) and ventrolateral (VL) strips of cortex that are reproduced at high magnification in Chapter 3, Figure 3-7 (pdf file #5, bottom list).
We think that the concepts presented in this book are relevant today, and this developmental treatise remains the most comprehensive study of neocortical development in any mammal. The recent research on gene expression studies confirms some of our observations and speculations about the mechanisms at work during neocortical development.