Walt Wilczynski

 Ph.D., University of MIchigan, 1978
Neuropsychology and Behavioral Neuroscience Program
390A Kell Hall 

Research Description

Research in my laboratory is in the area of neuroethology, the study of the neural basis of natural behavior. We focus on the neural and endocrine systems underlying animal communication and the role of communication signals in aggressive interactions and reproductive behavior. Research in my lab is multidisciplinary, using combinations of neuroanatomical, neuroendocrinological, neurophysiological, or behavioral techniques to gain a more complete understanding of the neural mechanisms underlying social behavior and its evolution.

Socioendocrinology of Animal Communication

The acoustic communication system of frogs and toads is a model for investigating the neural and hormonal mechanisms of animal communication. As in many other systems, the vocal exchanges between frogs are part of the seasonal social behavior associated with breeding and have mate attraction and aggressive functions. We are engaged in studying the reciprocal interactions between communication behavior and hormonal systems mediated through hypothalamic centers of the brain. This entails understanding two interacting aspects of the system: How are features of the communication behavior (vocal production, behavioral responses to the calls) controlled by hormones; and, how does the reception of communication signals modify hormonal state? Furthermore, what are the neural systems that control, and are in turn modified by, these behavioral and hormonal processes? For this project, studies in the lab are aimed at identifying the anatomy and physiology of central nervous system pathways that link the auditory system with the limbic areas controlling endocrine release and in assessing the plasticity in those systems. These studies complement behavioral work focused on the seasonal and hormonal regulation of female mate choice behavior and male vocalization.

Neuroethology of Male Aggression

Individuals vary greatly in their aggressiveness. This is due to a variety of interacting factors, including hormonal state and past experience. We are investigating these interacting factors in order to better understand how experience and hormonal state mutually influence each other, and how both contribute to influencing the limbic centers of the brain as these centers control aggression and other types of social behavior. The green anole lizard (Anolis carolinensis) is the model animal for this project. On the behavioral side, research focuses on the plasticity in aggression displayed by males as they interact with familiar and unfamiliar challengers. Endocrinological assessments have shown that both androgens and stress hormones change during successive aggressive interactions along with the behavioral modification. Current work investigates the possibility that the hormonal changes triggered by the aggressive interactions are important for the behavioral changes that occur with aggressive experience. Research in this area also targets possible sites of neural plasticity that might underlie the behavioral plasticity that aggressive social interactions cause. For example, we have used histochemical staining for the enzyme cytochrome oxidase as an anatomical marker of functional differences in limbic system brain regions as a result of social status (dominant or subordinate) or as a result of repeated aggression interactions with another individual.

Evolution of Communication Systems

Variation in signals, receiver characteristics, and behavior occurs at many levels within a communication system: among species, among geographically distinct populations within a species, among individuals within a population, and between sexes. Studying the pattern of this variation in relation to ecological and phylogenetic factors, as well as the consequences of this variation for sexual and natural selection provides insights into the evolution of communication and social behavior. We investigate the acoustic communication system of frogs and toads from this perspective in a variety of ways. Several projects have investigated the tuning characteristics of the peripheral and central auditory systems and their relationship to male call characteristics and female mate choice patterns within and across species. Supplementing this have been morphological studies of the larynx and ear to illuminate the underlying anatomical mechanisms between call and tuning differences among populations and between sexes. Many of these projects include a strong behavioral component in the laboratory or the field in order to ground the neuroscience work in a deeper understanding of how individuals use communication signals in their social interactions.

Representative Publications

Burmeister, S., and W. Wilczynski (2000). Social signals influence hormones independently of calling behavior in the treefrog (Hyla cinerea). Horm. Behav., 38: 201-209.

Yang, E.-J., S. M. Phelps, D. Crews, and W. Wilczynski (2001) The effects of social experience on aggressive behavior in Anolis carolinensis. Ethology, 107: 777-794.

Witte, K., M. J. Ryan, and W. Wilczynski (2001) Changes in frequency structure of a mating call decreases its attractiveness to females in the cricket frog Acris crepitans blanchardi. Ethology, 107: 685-700.

Burmeister, S., C. Somes, and W. Wilczynski (2001) Behavioral and hormonal consequences of exogenous vasotocin and corticosterone in the green treefrog. Gen. Comp. Endocrinol., 122: 189-197.

Chu, J., and W. Wilczynski (2001). Social influences on androgen levels in the southern leopard frog, Rana sphenocephala. Gen. Comp. Endocrinol., 121: 66-73.

Wilczynski, W., A. S. Rand, and M. J. Ryan (2001) Evolution of calls and auditory tuning in the Physalaemus pustulosus species group. Brain Behav. Evol., 58: 137-151.

Yang, E. J., and W. Wilczynski (2002) Relationships between hormones and aggressive behavior in green anole lizards: An analysis using structural equation modeling. Horm. Behav., 42: 192-205.

Burmeister, S., A. G. Ophir, M. J. Ryan, and W. Wilczynski (2002) Information transfer during cricket frog contests. Anim. Behav., 64: 715-725.

Chu, J.C., and W. Wilczynski. (2002) Androgen effects on tyrosine hydroxylase cells in the forebrain in the Northern leopard frog. Neuroendocrinology, 76: 18-27.

Yang, E. J., and W. Wilczynski (2003) Interaction effects of corticosterone and experience on aggressive behavior in the green anole lizard. Horm. Behav., 44: 281-292.

Hoke, K. L. S. S. Burmeister, R. D. Fernald, A. S. Rand, M. J. Ryan, and W. Wilczynski (2004) Functional mapping of the auditory midbrain during mate call reception. J. Neurosci. 24:11264 –11272.

Plavicki, J., E.-J. Yang, and W. Wilczynski (2004) Dominance status predicts response to nonsocial exercise stress in the green anole lizard (Anolis carolinensis). Physiol. Behav., 80: 547-555.

Lynch, K. S., and W. Wilczynski (2005) Gonadal steroid fluctuations in a tropically breeding female anuran. Gen. Comp. Endocrinol., 143: 51-56.

Witte, K., H. E. Harris, M.J. Ryan, and W. Wilczynski (2005) How cricket frog females deal with a noisy world: evidence for environmental selection on tuning. Behav. Ecol., 16:571–579.

Burmeister, S., W. Wilczynski (2005) Social signals regulate gonadotropin-releasing hormone neurons in the green treefrog. Brain Behav. Evol. 65:26-32.

Lynch, K. S., A. S. Rand, M. J. Ryan, and W. Wilczynski (2005) The influence of reproductive stage in producing within-individual plasticity in female mate choice. Anim. Behav. 69: 689–699.

Wilczynski, W., K. S. Lynch, E. L. O’Bryant (2005) Current research in amphibians: Studies integrating endocrinology, behavior, and neurobiology. Horm. Behav., 48: 440-450.

Hoke, K.L., M. J. Ryan, W. Wilczynski (2005) Social cues shift functional connectivity in the hypothalamus. Proc. Nat. Acad. Sci. USA, 102: 10712-10717.

Walt Wilczynski Photo