People Detail

Faculty Biography For:

Gregg Roman
Associate Professor
Ph.D. University of Pennsylvania, 1995

Biology and Biochemistry Department
University of Houston
Houston, Texas 77204-5001

Office: SR2 421G
Phone: (713) 743-5738

Drosophila Behavioral Genetics
My laboratory is interested the molecular and cellular mechanisms of behavior. Our work focuses on three behavioral areas that share important neural processes: 1) associative memory, 2) exploration, and 3) behavioral responses to alcohol. We are currently investigating mechanisms that govern these behaviors using Drosophila melanogaster as our model system. The application of the modern genetic tools available in Drosophila allows us to finely dissect the molecular events underlying behavioral plasticity.

Associative learning
In a classical conditioning paradigm, flies are presented with an odor (CS ) paired with an electric shock (US). The flies are then presented with a second odor (CS-) that is unpaired to the US. The associative memory is then measured as the number of trained flies choosing the CS- over the CS in a T-maze. A fly that has learned to associate the electric shock with the CS odor will avoid that odor within the T-maze. The mushroom body neurons in the Drosophila brain are essential for the formation of this associative olfactory memory. Our lab uses transgenic tools and classical genetic approaches to dissect the the molecular events occurring within the mushroom body neurons that are required for the acquisition, consolidation and recall of these associative memories. Part of our work in this area uses the S1 subunit of pertussis toxin to inhibit heterotrimeric G(o) signaling. We have shown that there is an absolute requirement for G(o) activity for olfactory associative learning. By combining functional imaging, transgenic manipulation, and behavioral analysis, we demonstrated that the activation of G(o) is required to presynaptically inhibit mushroom body neurons for negatively-reinforced olfactory memory formation.

Exploration comprises the specific behaviors, elicited by novelty, which permit the collection of information about unfamiliar parts of the environment. Drosophila melanogaster respond to novelty in an open field arena with an increased movement and a directional persistence. As the fly learns the arena, the activity and persistent forward movement decay to spontaneous levels. In order to better understand the behavior and separate the directed movements involved in learning from random movements, we have developed phenomenological models of this behavior. Our goals for this project are to dissect the neurobiology of this behavior: determine which neurons and which molecular pathways are required for exploration. We are also interested in the learning process involved; understanding how the flies learn the environment and abate the novelty. Lastly, we are interested in the expression of this behavior in diverse Drosophila species.

Ethanol Neurobiology
Alcohol abuse and addiction represents one of the most serious health problems facing our country. The descent from abuse to alcohol dependence is largely a problem of altered reinforcement. Alcohol use can provide both positive reinforcement, hedonistic feelings and a reduction in anxiety, and negative reinforcement, intoxication and physical illness. Binge drinking episodes result in tolerance and reduced negative reinforcement, permitting higher levels of alcohol use. Our lab is interested in understanding the mechanisms by which alcohol use results in altered alcohol reinforcement using Drosophila melanogaster as our model system. Drosophila melanogaster likes to drink alcohol and as in humans, alcohol is positively reinforcing. Also, similar to humans, in Drosophila exposure to alcohol will lead to tolerance formation. Our lab is currently examining presynaptic mechanisms for tolerance formation and alcohol self-administration. Understanding the mechanisms underlying these processes may provide new drug targets to fight the development of alcohol dependence and to help battle recidivism.

Current Biology, 23(24):2519-27.

Roman G. (2004). The genetics of Drosophila transgenics. Bioessays, 26(11):1243-53.

Ferris, J. H. Ge, L. Liu, and G. Roman. 2006. G(o) signalling is required for Drosophila associative learning. Nature Neuroscience. 9: 11036-1040.

Ge, H., P. Krishnan, L. Liu, B. Krishnan, S.E. Dryer, R.L. Davis, P.E. Hardin, and G. Roman. 2006. Mutants of the kurtz non-visual arrestin of Drosophila have significantly blunted olfactory responsiveness. Chemical Senses 31: 49-62.

Libert S., Zwiener J., Chu X., Vanvoorhies W., Roman G., Pletcher S.D. 2007. Regulation of Drosophila life span by olfaction and food-derived odors. Science 315(5815):1133-7.

Liu, L., R.L. Davis, G. Roman. 2007. Exploratory activity in Drosophila requires the kurtz non-visual arrestin. Genetics 175: 1197-1212.

Rawashdeh, O., N.H. de Borsetti, G. Roman, G. Cahill. 2007. Melatonin suppresses nighttime memory formation in zebrafish. Science. 318: 1144-1146.

Nicholson L, Singh GK, Osterwalder T, Roman GW, Davis RL, Keshishian H. (2008). Spatial and temporal control of gene expression in Drosophila using the inducible GeneSwitch GAL4 system. I. Screen for larval nervous system drivers. Genetics, 178(1):215-34.

Benito J., J.H. Houl, G. Roman, P. Hardin. 2008. The blue light photoreceptor CRYPTOCHROME is expressed in a subset of circadian oscillator neurons in the Drosophila CNS. J. Biol. Rhythms 23(4):296-307.

Lyons L, G. Roman. Circadian Modulation of Short-Term Memory in Drosophila. 2009. Learning and Memory 16(1): 19-27.

Nature Neuroscience 16, 441448.

Poon, P., T Kuo, N. J. Linford, G. Roman, and S. D. Pletcher. 2010. Carbon dioxide sensing modulates lifespan and physiology in Drosophila. PLoS Biology. 8(4): e1000356.