Neurobiology of behaviour Editorial overview John H Byrne and Wendy A Suzuki Current Opinion in Neurobiology 2006, 16:668–671 Available online 13th November 2006 0959-4388/$ – see front matter Published by Elsevier Ltd. DOI 10.1016/j.conb.2006.10.011 John H Byrne Department of Neurobiology and Anatomy, WM Keck Center for the Neurobiology of Learning and Memory, The University of Texas Medical School at Houston, PO Box 20708, Houston, TX 77225, USA e-mail: john.h.byrne@uth.tmc.edu John H Byrne is currently the Professor and Chairman of the Department of Neurobiology and Anatomy and Director of the Neuroscience Research Center at the University of Texas Medical School at Houston. He is also the Director of the WM Keck Center for the Neurobiology of Learning and Memory at the UT Health Science Center. His research uses a combination of experimental and computational approaches to understand the cellular and molecular mechanisms of learning and memory. Wendy A Suzuki Center for Neural Science, New York University, 4 Washington Place, Room 809, New York, NY 10003, USA e-mail: wendy@cns.nyu.edu Wendy Suzuki is an Associate Professor of Neural Science at the New York University. Her laboratory studies the patterns of neural activity seen during acquisition, consolidation and retrieval of memories dependent on the medial temporal lobe. To address this question they use a combination of carefully designed behavioral tasks and single unit electrophysiological recording techniques. Most recently, they have been developing more ethologically based behavioral tasks to study memory in non-human primates. Introduction For more than one hundred years, scientists have been developing and applying a wide range of approaches to understand the relationship between brain activity and behaviour. Indeed, this question constitutes one of the holy grails of modern neuroscience research. For this section of Current Opinion in Neurobiology, we have solicited a series of articles that represent the enormous breadth and depth of the approaches being brought to the study of behavior. These investigations range from the study of the molecular machinery that regulates circadian rhythms to the study of the cognitive control of emotional information. Throughout this wide range of articles, two clear themes are present. The first theme highlights the crucial insights we have gained from work linking molecular and gene networks to specific systems that underlie behavior. The second theme highlights the important advances that have been made in understanding the brain basis of memory and cognition through parallel studies in human and animal model systems. Cellular and molecular approaches One of the striking developments in neurobiology over the past several decades has been the identification and characterization of the biochemical and gene networks that underlie specific features of behavior and behavioral modifications such as those that occur through learning. This section includes three articles that emphasize key findings over the past several years, which have exploited the technical advantages of the marine mollusk Aplysia and of the fruit fly Drosophila. For more than thirty years, work on these two invertebrates has helped enormously to provide key insights into the neurobiology of behavior, and, as the three articles in this section highlight, they have continued to do so. Two of the articles, one by Stough, Shobe and Carew and the other by Liu and Davis, review new developments in the understanding of the different temporal domains of memory and how the different domains can be localized in different brain regions. The third article, by Hardin, provides new insights into the gene and protein network underlying the generation of circadian rhythms. Memory has been traditionally divided into short-term and long-term domains. Short-term memory lasts up to several minutes and relies on modification of pre-existing proteins, whereas long-term memory can last up to a lifetime and relies on synthesis of new proteins. In their article, Stough, Shobe and Carew review recent studies of sensitization in Aplysia, which have revealed the existence of two forms of intermediate-term memory that are distinct from short-term and long-term memory, both temporally and mechanistically. One form of intermediate-term sensitiza- tion and the synaptic facilitation associated with it lasts from 30 min to 3 h after training (depending on the training protocol), and, similar to long-term memory, it is blocked by inhibitors of protein synthesis. However, in Current Opinion in Neurobiology 2006, 16:668–671 www.sciencedirect.com