Contents



Preface

It has been more than 400 years since the hippocampus was first described. As early as 1578, Arantius described the processes at the bottom of the temporal angle as the hippocampus. Based on the ventricular morphology, in 1732 Winslow suggested using the noun "ram horn" for the structure. In the same period, De Garengeot used the term Cornu Ammonis for the hippocampus, referring to the Egyptian god Amun, who has the head of a ram. Research has made the structure and function of the hippocampus clearer and clearer, but there are still many unknown secrets.

The hippocampus is a bicortical structure composed of the Cornu Ammonis and dentate gyrus. They are interlaced with each other, and separated from each other, bounded by the hippocampal sulcus. The hippocampus belongs to the oldest part of the evolution of the brain, namely, the paleocortex. The Cornu Ammonis has three layers: the molecular, pyramidal, and pleomorphic layers. The cortex of the dentate gyrus is also divided into three layers: the molecular, granular, and pleomorphic layers. In the granular cell layer, the marginal area near the hilus is called the subgranular layer, where in the 1960s and 1970s it was found that there are neural stem cells with self-renewal and multi-differentiation potential in adult mammals. The subgranular layer is one of the few areas of the nervous system where postnatal neurogenesis occurs. Studies have shown that the dentate gyrus of primates still retains proliferative precursor cells in adulthood, but few in the aged. Therefore, the hippocampus has the ability of neurogenesis, and the existence of neural stem cells

also provides a basis for hippocampal structure and functional plasticity.

depends on the neocortex.

There are extensive fiber connections between the hippocampus and other brain regions. The afferent fibers of the hippocampus mainly include perforating fibers from the entorhinal cortex and septal-hippocampal fibers from the septal nucleus. The fimbria fornix is the main efferent pathway of the hippocampus. In addition to terminating the mammillary body, there are fibers ending in the cingulate gyrus, septal nucleus, preoptic area, lateral hypothalamic area, anterior thalamic nucleus, and so on. Because of these connections, the hippocampus is involved in a variety of functions, such as learning, memory, attention, emotion, sensory information processing, and motor function. The hippocampus plays a crucial role in learning and memory, involving all aspects of narrative memory. Information from the neocortex converges to the entorhinal region and then further reaches the hippocampus. Therefore, the newly acquired information is filtered through the hippocampus before reaching the neocortex. The hippocampus can judge whether it is new or recent information, and the identification of old information mainly

The first part of this book consists of four chapters that introduce the cytoarchitecture and functions of the hippocampus. Chapter 1 by Jing et al. describes the learning and memory-related circuits and fiber connections of the hippocampus. Chapter 2 by Bastos et al. states the correlation between fiber autofluorescence and postsynaptic zinc dynamics of pyramidal CA3 neurons. Chapter 3 by Luo et al. focuses on the pattern formation process of entorhinal cortex grid cells. Chapter 4
