Book Review: The Mechanism of Vision
Yoshinori Shichida and Daisuke Kojima, Kyoritsu Shuppan, November 2023, 141 pages, 2000 yen (excluding tax)
This book is an excellent work that provides a detailed explanation of the mechanisms of vision, weaving together a wide range of perspectives from structural biology and evolution to physics and chemistry. As noted in the afterword, the book was adapted and expanded for a general audience from the author's university lecture notes. Therefore, while its content is undoubtedly useful for undergraduate and graduate students pursuing biology, it is also a very rewarding read for scientists working in fields other than biology and for the general public. Reading this book brought back fond memories of Professor Shichida's lectures on "Molecular Information Science" that I attended when I was an undergraduate in the Faculty of Science at Kyoto University.
Chapter 1 provides an overview of the history of research on visual pigments and photoreceptor cells responsible for visual function, as well as the diversity of visual systems. Chapter 2 clearly explains the structure and development of the eye and retina, incorporating interspecies comparisons. Chapter 3 provides a detailed explanation of the light-response mechanisms of vertebrate and invertebrate photoreceptor cells, focusing particularly on signal transduction pathways. Chapter 4 describes findings on visual pigments from a structural biology perspective and discusses the diversity of light-response processes. Chapter 5, titled The Mechanism of Color Vision, supports the classic theories of color vision—the Young-Helmholtz trichromatic theory and the opponent-process theory—from the perspective of visual mechanisms. Chapter 6 details how visual information is processed in the retina, starting with an explanation of concepts such as the receptive field. Chapter 7, the final chapter, explains the process by which visual information is transmitted to the brain, dividing the explanation into transmission from the retina to the primary visual cortex, and beyond the primary visual cortex.
While I was overwhelmed by the sheer depth and richness of the content, I also had some doubts regarding certain evolutionary arguments. For example, regarding these two sentences in Section 1.3: "What is interesting from the perspective of cell evolution and diversification is the order in which neurons differentiate during ontogeny. This is because the order of neuronal differentiation in ontogeny correlates to some extent with the emergence of new cell types in the evolutionary process." My understanding is that, generally speaking, although a "parallel" has been observed where ontogeny reflects the evolutionary process, it is considered difficult to directly estimate the evolutionary process solely from ontogeny. Rather, regarding how new cell types were acquired in the course of evolution, I believe it is necessary to compare which cell types are acquired in which taxonomic groups against phylogenetic relationships. That being said, given that the book provides a detailed and concise summary of the visual system, coupled with its affordable price, it can be said to be a work of extremely high value.
Kazuki Sakura (National Institute for Basic Biology, Division of Evolutionary Development)
