Adult Neurogenesis, by Kempermann, is a comprehensive volume which aims to synthesise decades of research in this evolving field. This third edition of this landmark book aims to introduce the provocative and rapidly advancing concept of adult neurogenesis to a broad spectrum of readers. This heavy white book stands at 765 pages and it aims to serves as an essential guide through the explosion of literature in this subject.
The book defines adult neurogenesis as production of new, functional neurons in an adult brain. Adulthood in this book is defined as the earliest age a mammal can reproduce, therefore will correspond with the beginning of puberty.
The volume is split into 12 chapters. The first chapters describe the history of the initial discovery of adult neurogenesis, starting with the first research publications of adult neurogenesis in the 1960s by Joseph Altman, described as the undisputed father of adult neurogenesis who first discovered evidence of this process in the hippocampus. Then guides the reader through further studies into the 1990s lauding the discovery of neural stem cells and evidence of adult neurogenesis in the olfactory bulb.
In the next few chapters, the book delves into the definition and function of neuronal stem cells within neurogenesis, this leads into neuronal development which steers the reader through embryonic brain development in order to understand the foundations of neurogenesis.
This is followed by detailed reviews of the two areas in the brain identified as neurogenic areas: the olfactory bulb and the adult subventricular zone (SVZ) within the olfactory system, and the dentate gyrus in the hippocampus. The first of these chapters describes the lesser studied process of neurogenesis within the SVZ, describing the process of interneuron and oligodendrocyte formation from precursor cells via migratory mechanisms. This dentate gyrus has been more intensely studied with the author noting there is four times the amount of literature compared to the olfactory system within this field. The structure and function of the hippocampus is clearly explained with overview of its function including cognition. The process of neurogenesis within the dentate gyrus is described through four phases; the precursor phase, with expansion of the precursor cell pool with a distinct astrocytic population, the early survival phase, the maturation phase, and the late survival phase following functional integration.
Given the complexity of this research field, this book dedicates the next chapter to research methods in adult neurogenesis, describing immunohistological tools such as cell cultures, neuronal markers and also genetic tools and molecular approaches.
The next sections cover the neurogenic and non-neurogenic regions of the brain, acknowledging reports of exceptional neurogenesis in the non-neurogenic region – however, the evidence for this process outside of the two described regions of the brain is controversial and not well accepted. The author acknowledges emerging research on evidence of adult neurogenesis in the hypothalamus, but this requires further investigation. Other regions of the brain such as the neocortex, other structures in the hippocampus, the piriform cortex and the amygdala are also discussed, however the evidence for adult neurogenesis in these regions is low.
The next section of the book covers the regulation of adult neurogenesis. At this point the book discusses the ageing process, and previous notions that the strongest negative regulator of neurogenesis is age. However, this does not seem to be the linear deterioration previously described. The author reports that the highest level of neurogenesis is in early adulthood and during puberty, then quickly decreases; ageing then does not exert a further strong influence and even in old age adult neurogenesis can be detected. The models of regulation and immune cells involved are described in detail. This is followed by an overview of the function of the new neurons and functional relevance of neurogenesis, primarily studies in the rodent brain.
The final chapter is possibly the most relevant to practising clinicians working within neurology and neurorehabilitation. This focuses on the medical relevance of adult neurogenesis. The author notes the popularity of this concept within the media which can lead to the concept being misused, for example production of self help books with the aim of ‘boosting neurogenesis’.
This book takes the reader through a variety of medical conditions and shows the impact adult neurogenesis may have. For example, the author discusses brain tumours, and how the control of proliferation and development may fail and lead to development of tumours. It gives insights into how chemotherapy and radiotherapy, viral infections and seizures can impact on adult neurogenesis. The author expands on research in neurodegenerative conditions which has focused on Alzheimer’s disease (AD) and Parkinson’s disease (PD). The author considers whether the process of adult neurogenesis might contribute to building of a ‘cognitive reserve’ that helps explain the inconsistency between the amount of neuropathological alteration and the level of cognitive impairment. This chapter also covers neurogenesis in stroke, trauma and spinal cord injury and describes evidence of a neurogenic response after injury and increase in neurogenesis in the adult hippocampus after stroke.
The conclusions state that currently adult neurogenesis is a fundamental, albeit exceptional, mechanism of brain plasticity. It does not seem to be a tool for brain repair, instead contributes to basic function. Currently the medical applications are limited, but this book happily states that the relevance of this advancing research field is to develop deeper understanding of the mechanisms by which the brain works and how this contributes to who we are as individuals.
One limitation of this book is the high level of technical complexity, however the author breaks down the concepts to be mostly understood by someone new to this field. It is a rigorous and comprehensive volume with inclusion of the most up to date research. There were some sections which a casual reader, who is not a neuroscientist or researcher, would find very difficult to follow. The aim of this book is to bring this concept to a broader range of readers, and I think it is successful. The author follows a logical order to breaking down the concept, concluding with its application to clinical practice. The book addresses its limitations and acknowledges the unanswered questions which require ongoing research. This field will likely develop further over time and may become more relevant to working clinicians. This book would be recommended for anyone with an interest in this concept as it gives a broad overview of the subject and directs the reader to specific studies if further information is required.
