I have broad research interests that overlap and combine the fields of neuroendocrinology, chemoreceptive sciences and behavioral neuroscience.  My research program addresses fundamental questions about the neural control of social behavior at cellular, systems and behavioral levels. One aspect of my research addresses the relative roles of different chemosensory systems or subsystems for the processing and perception of chemosensory cues that influence social behavior.

I utilize mice with targeted deletions of genes critical for signal transduction in chemosensory neurons. For example mice with a deletion of the transient receptor potential channel subunit 2 (TRP2) have strongly impaired pheromone responses in the vomeronasal organ, while mice with a targeted deletion of the cyclic nucleotide gated channel subunit 2 (CNGA2) exhibit no odor responses in olfactory receptor neurons. Using these two lines of mice as models, I am examining how the two olfactory systems interact to control social behavior. One of the unique features of my behavioral research program is that I use a combination of both preference and operant discrimination behavioral tasks. Using both of these types of tasks makes it possible to differentiate between discrimination of and motivation for biologically relevant chemosensory stimuli.  Differentiating discrimination from motivation is of critical since understanding motivation is the key to revealing how chemosensory cues control social behavior.  In addition to various behavioral tasks, I will use anatomical markers of neuronal activation such as c-fos immunocytochemistry to explore functional activation of each of these sensory systems in the absence of its counterpart.

Another aspect of my research includes the study of major histocompatibility complex (MHC) related odors, and how these odors may pass along information of genetic individuality using both the main and accessory olfactory systems. MHC genes, which in the immune system are responsible for signaling self vs. non-self recognition of cells, also convey genetic individuality through chemosignals present in biological fluids. I am investigating MHC class I peptides ligands, which can be excreted in urine, by analyzing the mechanisms that underlie detection of these chemical cues.  To accomplish this, we are using a combination of electrophysiological techniques, recording field potentials in the main olfactory epithelium, and behavioral tasks, such as recognition and preference tests. Additionally, we are using both CNGA2-KO and TRPC2-KO mice to understand which olfactory system (main vs. accessory) is necessary for detection and processing of MHC related odors in the context of each behavior. Interestingly, it appears that both the main and accessory olfactory systems are capable of detecting MHC related odors but may be responsible for mediating different aspects of individual recognition.

Recent Publications

Zufall F, Kelliher KR, Leinders-Zufall T (2002) Pheromone detection by mammalian vomeronasal neurons. Microsc. Res.  Tech. 58: 251-260.

Kelliher KR, Ziesmann J, Munger SD, Reed RR, Zufall F (2003) Importance of the CNGA4 channel gene for odor discrimination and adaptation in behaving mice.  Proc. Nat. Acad. Sci. 100:4299-4304.

Wersinger, SR*, Kelliher KR*,  Zufall F, Lolait SJ, O'Carroll A-M, Young WS  (2004) Social motivation is reduced in vasopressin 1b receptor null mice despite normal performance in an olfactory discrimination task.  Horm. Behav.  46:638-645.

Spehr M, Kelliher KR, Li X-H, Boehm T, Lienders-Zufall T, Zufall F  (2006) CNGA2 mutant mice reveal an essential role of the main olfactory system in social recognition of MHC peptide ligands. J. Neurosci.  26:1961-1970

Kelliher KR, Spehr M, Li X-H, Zufall F, Lienders-Zufall T  (2006) Pheromonal recognition memory induced by TRPC2-independent vomeronasal sensing. Eur. J. Neurosci 23:3385-9

Spehr M, Spehr J, Ukhanov K, Kelliher KR, Leinders-Zufall T, Zufall F (2006)  Parallel processing of social signals by the mammalian main and accessory olfactory systems Cell Mol. Life Sci. 63:1476-84