Much of my published research concerns the hormonal and neural regulation of pheromonal and ultrasonic communication in house mice (Mus musculus). For example, male mice emit ultrasonic calls at around 70 kHz when courting and copulating with female mice. These ultrasounds are, in turn, elicited by female pheromones.
Ethological, genetic, endocrine, neurological, sound-spectrographic, and perceptual findings by myself and others all point to male calling conveying important information to the female during sexual encounters. Female mice emit few or no calls in this context (although they are quite capable of doing so). It is telling that female hearing is selectively tuned to the frequency at which males call and presumably this auditory information would be important in timing aspects of mouse reproductive physiology and behavior.
Male calling to females begins at puberty and is androgen regulated, with androgens acting primarily in the preoptic area of the brain (an area important for male-typical motivation and behavior). Female calling can be enhanced by androgen treatment in adulthood suggesting that the sex difference is regulated more by the activational, than the organizational, effects of hormones.
My lab found that female urine contains at least 2 nonvolatile pheromones that stimulate male calling: a highly salient, but ephemeral, pheromone to which males innately respond, which degrades within 24 hours by oxidation; and a less salient, but longer lasting, pheromone in which male learning plays a significant role in responsiveness. The principal sensory system by which the male detects these pheromones is the vomeronasal organ although the main olfactory system can also mediate responsiveness in sexually experienced males. Somewhat unexpectedly, female pheromone activity doesn’t vary much across the female’s estrus cycle but rather appears regulated by the pituitary.
More details on my research on pheromonal and ultrasonic communication in mice can be found in several reviews (Nyby, 2001, 2010).
My lab also has investigated the quick, possibly nongenomic, effects of testosterone on male behavior. Complementing the quick rewarding effects of testosterone demonstrated by others, male mice engage more quickly in copulatory behavior and also show evidence of reduced anxiety immediately following androgen treatment (Nyby, 2008).
Recently we found that ghrelin, an orexigenic hormone released by the stomach, inhibits male mouse calling to females (and intermale aggression) quicker than predicted from its known suppression of the HPG axis (Shah & Nyby, 2010,). We hypothesize that ghrelin inhibits some male-typical reproductive behaviors through its actions in integrative brain areas and may provide yet another important tool for dissecting the neuroanatomy of male reproduction.
I also have performed research on territorial scent marking and food hoarding in gerbils, field work on reproductive and parental behavior cichlids in Texas and Costa Rica, the sociobiology of child custody law suits in humans, and recently have become interested in the behavioral ecology of fence lizards in Northern California.
I am also the founder and director of the undergraduate program in Behavioral Neuroscience and for 5 years served as the undergraduate coordinator in the Dept. of Biological Sciences for our major programs in biology, molecular biology, behavioral neuroscience, and our interdisciplinary program with the Chemistry Department in biochemistry.
Thiessen, D.D., Lindzey, G.L. & Nyby, J. The effects of olfactory deprivation and hormones on territorial marking in the male Mongolian gerbil (Meriones unguiculatus). Hormones and Behavior, 1970, 1, 315-325.
Nyby, J., Thiessen, D.D. & Wallace, P. Social inhibition of territorial marking in the Mongolian gerbil (Meriones unguiculatus) Psychonomic Science, 1970, 21, 310-312.
Nyby, J. & Thiessen, D.D. Singular and interactive effects of testosterone and estrogen on territorial marking in the castrated male Mongolian gerbil (Meriones unguiculatus). Hormones and Behavior, 1971, 2, 279-285.
Nyby, J., Wallace, P., Owen, K. & Thiessen, D.D. An influence of hormones on hoarding behavior in the Mongolian gerbil (Meriones unguiculatus). Hormones and Behavior, 1973, 4, 283-288.
Nyby, J., Belknap, J. & Thiessen, D.D. The effects of d- and 1-amphetamine upon hoarding behavior and feeding in the Mongolian gerbil (Meriones unguiculatus). Physiological Psychology, 1974, 2, 297-499.
Nyby, J., Dizinno, G., Whitney, G. Social status and ultrasonic vocalizations of male mice. Behavioral Biology, 1976, 18, 285-289.
Nyby, J., Wysocki, C.J., Whitney, G., and Dizinno, G. Pheromonal regulation of male mouse courtship. Animal Behaviour, 1977, 25, 333-341.
Nyby, J., Dizinno, G. & Whitney, G. Sexual dimorphism in ultrasonic vocalizations of mice (Mus musculus): Gonadal hormone regulation. Journal of Comparative and Physiological Psychology, 1977, 91, 1424-1431.
Nyby, J., Whitney, G., Schmitz, S. & Dizinno, G. Postpubertal experience establishes signal value of mammalian sex odor. Behavioral Biology, 1978, 22, 545-552.
Dizinno, G., Whitney, G. & Nyby, J. Ultrasonic vocalizations by male mice (Mus musculus) in response to female sex pheromone: Effects of experience. Behavioral Biology, 1978, 22, 104-113.
Schneider, J., Wysocki, C., Nyby, J. & Whitney, G. Determining the sex of neonatal mice. Behavioral Research Methods and Instrumentation, 1978, 10, 105.
Nunez, A., Nyby, J. & Whitney, G. The effects of testosterone, estradiol, and dihydrotestosterone on male mouse (Mus musculus) ultrasonic vocalizations. Hormones and Behavior, 1978, 11, 264-272.
Nyby, J., Wysocki, C.J., Whitney, G., Dizinno, G. & Schneider, J. Elicitation of male mouse (Mus musculus) ultrasonic vocalizations I. Urinary cues. Journal of Comparative and Physiological Psychology, 1979, 93, 957-975.
Nyby, J. & Zakeski, D. Elicitation of male mouse ultrasounds: bladder urine and aged urine from females. Physiology and Behavior, 1980, 24, 737-740.
Nyby, J. & Thiessen, D.D. Food hoarding in the Mongolian gerbil (Meriones unguiculatus): Effects of food deprivation. Behavioral and Neural Biology, 1980, 30, 39-48.
Nyby, J., Wysocki, C.J., Whitney, G., Dizinno, G., Schneider, J. & Nunez, A. Stimuli for male mouse (Mus musculus) ultrasonic courtship vocalizations: presence of female chemosignals and/or absence of male chemosignals. Journal of Comparative and Physiological Psychology, 1981, 95, 623-629.
Itzkowitz, M. & Nyby, J. A parental sex difference in child custody suits. Ethology and Sociobiology, 1981, 2, 147-149.
Wysocki, C.J., Nyby, J., Whitney, G., Beauchamp, G.K. & Katz, Y. The vomeronasal organ: primary role in mouse chemosensory gender recognition. Physiology and Behavior, 1982, 29, 315-327.
Itzkowitz, M. & Nyby, J. Field observations of parental behavior of the Texas cichlid, Cichlasoma cyanoguttatum. The American Midland Naturalist, 108, 1982, 364-368
Nyby, J., Bigelow, J., Kerchner, M. & Barbehenn, F. Male mouse (Mus musculus) ultrasonic vocalizations to female urine. Why is heterosexual experience necessary? Behavioral and Neural Biology, 1983, 38, 32-46.
Nyby, J. Ultrasonic vocalizations during courtship and sex behavior in mice. Behavioral and Neural Biology, 1983, 39, 128-134.
Nyby, J., Bean, N.J., Kerchner, M. & Dahinden, Z. Male mouse attraction to airborne urinary odors of conspecifics and to food odors: effects of food deprivation. Journal of Comparative Psychology, 1985, 99, 479-490.
Byatt, S. & J. Nyby. Hormonal regulation of chemosignals that elicit ultrasonic vocalizations from males. Hormones and Behavior, 1986, 20, 60-72.
Bean, N.J., Nyby, J., Dahinden, Z. & Kerchner, M. Hormonal regulation of male mouse attraction to female urine. Hormones and Behavior, 1986, 20, 390-404.
Kerchner, M., Vatza, E., & Nyby, J. Ultrasonic vocalizations by male housemice (Mus musculus) to novel odors. The roles of infant and adult experience. Journal of Comparative Psychology, 1986, 100, 253-261.
Nyby, J. G. & N. G. Simon. Nonaromatizable androgens may stimulate a male mouse reproductive behavior by binding estrogen receptors. Physiology and Behavior, 1987, 39, 147-151.
Nyby, J., Matochik, J. A., & Barfield, RJ. Intracranial androgenic and estrogenic stimulation of male-typical behaviors in house mice (Mus domesticus). Hormones and Behavior, 1992, 26, 24-45.
Jubilan, B. & Nyby, J. The intrauterine position phenomenon and precopulatory behaviors of house mice. Physiology and Behavior, 1992, 15, 857-872.
Kay, E. & Nyby, J. LiCl aversive conditioning has transitory effects on pheromonal responsiveness in male house mice (Mus domesticus). Physiology and Behavior, 1992, 52, 105-113.
Sipos, M. & Nyby, J. An ephemeral sex pheromone in the urine of female house mice. Behavioral and Neural Biology, 1992, 58, 138-143
Matochik, J. A., Barfield, R. J., and Nyby, J. Regulation of sociosexual communication in female Long-Evans rats by ovarian hormones. Hormones and Behavior, 1992, 26, 545-555.
Sipos, M. L., Nyby, J. G., & Serran, M. F. An ephemeral sex pheromone of female house mice (Mus domesticus): Pheromone fade-out time. Physiology and Behavior, 1993, 54, 171-174
Matochik, J. A., Sipos, M.L., Nyby, J. G. & Barfield, R. J. Intracranial androgenic activation of male-typical behaviors in house mice: motivation versus performance. Behavioural Brain Research, 1994, 141-149.
Sipos, M. L., Alterman, L., Perry, B., Nyby, J.G., Vandenbergh, J.G. An ephemeral pheromone of female house mice: Degradation by oxidation. Animal Behaviour, 1995, 50, 113-120.
Sipos, M. L., Wysocki, C. J., Nyby, J. G., Wysocki, L., & Nemura, T. A. An ephemeral pheromone of female house mice: Perception via the main and accessory olfactory systems. Physiology and Behavior, 58, 1995, 529-534.
Sipos, M. L. and Nyby, J. G. Concurrent androgenic stimulation of the ventral tegmental area and medial preoptic area: Synergistic effects on male-typical reproductive behaviors in house mice. Brain Research, 729, 1996, 29-44
White, N. R., Prasad, M., Barfield, R. J., and Nyby J. G. 40 kHz and 70 kHz vocalizations of mice (Mus musculus) during copulation. Physiology and Behavior, 1998, 63, 467-73
Sipos, M. L. & Nyby, J. G. Intracranial androgenic activation of male-typical behaviors in house mice: Concurrent stimulation of the medial preoptic area and the medial nucleus of the amygdala. Journal of Neuroendocrinology, 1998, 10, 577-586
James, P. J. and Nyby, J. G., Testosterone rapidly affects the expression of copulatory behavior in house mice (Mus musculus), Physiology and Behavior, 2002, 75, 287-294.
Aikey, J,L., Nyby, J. G., Anmuth, D. M., James P. J. Testosterone rapidly reduces anxiety in house mice (Mus musculus), Hormones and Behavior, 2002, 42, 448-460.
Shah, S. N. & Nyby, J. G. Ghrelin’s quick inhibition of androgen-dependent behaviors of male house mice (Mus musculus). Hormones and Behavior, 2010 57,291-296
Snekser, J. L., Santangelo, N., Nyby, J. & Itzkowitz, M. Sex differences in biparental care as offspring develop: a field study of convict cichlids (Amatitlania siquia). Environmental Biology of Fishes, 2011, 91, 15-25.