Synaptogenesis in the adult CNS-Hippocampus

Abstract

It has long been known that the hippocampus plays essential roles in declarative memory, and it is crucial for the constructionof spatial maps (Johnston and Amaral, 2005). These well-established functions rely on a fundamental characteristicof hippocampal circuits: plasticity. Plasticity is the capacity of networks to modify its basic characteristics ofinformation flow by altering synaptic weights and intrinsic neuronal properties in a manner that changes the input/outputequation (Poo et al., 2016). Synapses undergo different forms of activity-dependent modification that may persistentlyenhance or reduce transmission between circuits. Long-lasting changes in synaptic strength are thought to be essential forlearning and information storage. In the hippocampus, generation and integration of new neuronsdadultneurogenesisdrepresents an additional and exclusive form of plasticity that is also present in the olfactory bulb. Neurogenesisis perhaps the most striking form of structural remodeling in the adult mammalian brain, and it relies onconcerted mechanisms of development, synapse formation, plasticity, and network homeostasis. It plays a critical role incognitive functions including spatial memory encoding and retention, retrieval, context discrimination, and clearance ofmemory traces. Impaired adult neurogenesis has been associated with cognitive dysfunctions that are commonly found inpatients with psychiatric disorders such as schizophrenia, depression, and anxiety. During aging, hippocampal neurogenesisdisplays substantial alterations in regard to maturation and integration of new GCs.