**Preface to "Recent Studies of Rodent Ultrasonic Vocalizations and Their Use in Experimental Models"**

This book contains publications included in the Special Issue of *Brain Sciences* entitled "Recent Studies of Rodent Ultrasonic Vocalizations and Their Use in Experimental Models", which appeared in print in 2021. The aim of this Special Issue was to review the most recent studies of rat ultrasonic vocalizations and to demonstrate their growing importance in many rodent models of neuropsychiatric and neurodevelopmental disorders and diseases. The Special Issue has not been planned as an exhausting review of publications on this topic, but rather as a presentation of selected studies from a vast array of research topics, in which rat vocalizations offer a reliable measure of animals'emotional arousal and changes in their physiological and pathological conditions. Thus, the goal of this book is to present exemplary studies from a diverse line of research, which will further demonstrate the importance of vocalizations as key behavioral measures and inspire researchers to explore other areas of behavioral neuroscience and neuropsychiatric modelling studies.

Emissions of ultrasonic vocalizations by rodents serve as innate intraspecies communication and a physiological regulator of behavior. Ultrasonic calls, however, may also be useful for researchers and play critical role in behavioral studies as indicator of animal emotional arousal, emotional valence, motivation, behavioral strategies and choices, as well as indicator of pathological changes in the animal brain, particularly in the limbic system, which influences vocal expression.

The book consists of different types of publications, as extensive review articles, short reviews, experimental papers, and methodological presentations that are based on exhaustive literature. The contemporary field of studies of rat ultrasonic vocalizations consists of several hundreds of published papers and is steadily growing. We believe that this book will provide a useful update of the newest results, trends, and lines of research in this field and will assist in planning further studies.

The editors would like to express thanks to the MDPI Publisher, and particularly to Ms. Seal Li, Section Managing Editor, for providing extensive help, guidance, and encouragement in preparing this publication.

> **Stefan M. Brudzynski, Jeffrey Burgdorf** *Editors*
