When an organism exhibits a given behavior or initiates a physiological process can be as important as whether it does so at all. From daily patterns of arousal and attention to annual patterns of reproduction and illness, biological clocks impinge on the behavior and physiology of humans and other animals. The research in the Chronobiology and Neuroimmunology Laboratory focuses on biological clocks in the brain. We are conducting experiments that seek to better understand the internal representation of time by identifying neural and endocrine mechanisms by which organisms mark the passing of the seasons.
Changes in the length of the day (the "photoperiod") function as important environmental signals for cueing seasonal clocks. However, the context within which a given photoperiod is experienced exerts a profound effect on an individual's response to it. Experiments using hamsters and mice as model systems focus on how changes in photoperiod interact with internal biological clocks to generate seasonal rhythms of thermoregulation, food intake, reproduction, and immune function. A major focus of our research includes specifying the environmental variables that provide context for the interpretation of external (photoperiod) and internal (clock-like) time signals.
The lab's research is concerned with the mechanisms that underlie the temporal structure of physiology and behavior. Nearly all behaviors are organized in time. Over the course of the day, the year, or the lifespan, thresholds for the activation of ingestive behavior, sex behavior, and social interactions (to name but a few), vary markedly. Most humans are buffered from the vicissitudes of the environment, but in nature, categorically different challenges to survival exist in daytime and at night, in winter and in summer. For the vast majority of organisms (and over most of human evolution), when an individual initiates a behavior or engages a physiological process can be as important as whether it occurs at all. Some environmental events repeat in such a predictable, cyclic manner that organisms have evolved biological timekeeping mechanisms ("clocks") that permit their anticipation. These timekeeping mechanisms extract information from the environment, maintain an internal representation of time, and communicate this information to physiological and behavioral systems critical to survival and adaptation - restricting some behaviors to particular fractions of the day or year. Identifying how these biological clocks operate is fundamental to a complete understanding of the causes of behavior.
Over the past decade, the lab's research has focused on elaborating mechanisms by which daily and seasonal time information are imparted into the reproductive and immune systems.