In the Behavior Genetics Lab, we study individual differences in behaviors that may increase the risk for behavioral disorders such as alcohol dependence or pathological gambling. We conduct candidate gene association studies in an attempt to better characterize the role of genetic variation in neurotransmitter system genes in the etiology of behavioral disorders. And we use control system modeling to generate hypotheses and to explore the pathway from gene to behavior in silico.
Areas of Interest
Impulsivity is a risk factor for a variety of health-risk behaviors, such as gambling, substance use and risky driving. There appear to be a variety of types of impulsivity such as boredom tolerance, failure to plan, quick responding, reduced response inhibition, etc. It also appears that these aspects of impulsivity vary quantitatively and are to some extent, independent of each other. We are interested in how the serotonin system might influence impulsivity and, by extension, propensity for engaging in health-risk behaviors.
Much of the work that I did while at the University of Michigan addressed issues surrounding alcoholism, especially the influence of Family History of alcoholism on risk and the influence of the serotonin system on a specific subtype of alcoholism called antisocial alcoholism. There is a tremendous amount of evidence that alcoholism runs in families, so individuals with a family history of alcoholism are at increased risk for developing alcohol related problems. The effects of family history may be moderated by gender and socioeconomic status. The risk for developing antisocial alcoholism for women has risen in recent years and may be an effect of the increased acceptance of women drinking and being drunk in public. Genes such as MAOA appear to be involved with risk for antisocial alcoholism.
Serotonin System Genes
One of my primary interests is to understand how genetic variation in serotonin system genes is related to behaviors that are influenced by serotonin function. There are several components of the serotonin system that vary genetically including: receptors, the transporter and various enzymes. The potential number of genetically different combinations of components is quite large, especially when one considers that there are at least 14 different types of serotonin receptors. Given this complexity, I use control system modeling to enable me to examine different genotype combinations and their potential effect on indices of serotonin function.
One good source of data to use in the computer simulations is candidate gene association studies. In these studies, we genotype people for particular genes in the serotonin system (e.g. TPH2) and then examine whether groups defined by genotype differ on the behavior of interest (e.g. response inhibition). Another source of input data for simulations is research literature on the serotonin system in mice.
My first work in behavior-genetic analysis was on geotaxis (orientation and movement with respect to gravity in fruit flies (Drosophila melanogaster). My Ph.D. advisor was Jerry Hirsch, who studied under R.C. Tryon, one of E.C. Tolman's students. Hirsch also did a post doc with Theodosius Dobzhansky. Geotaxis can be measured in a maze where flies go either up or down and assort themselves based on their behavior. Our work suggested that there was a gene near Adh on the second chromosome that was likely to influence geotaxis. We also showed that the Y-chromosome influenced geotaxis in male D. melanogaster.