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Karmen K Yoder Ph.D.
Assistant Professor, Department of Radiology, Psychology
Primary Appointment: IU School of Medicine
B.A., Psychology, University of North Carolina, Chapel Hill (1991)
Ph.D., Neurobiology, Indiana University School of Medicine (2002)
In Vivo Neurochemistry of CNS Disorders and Cognition using PET
Dr. Yoder's work focuses on using quantitative PET techniques to study in vivo neurochemical processes in humans and in animal models of abnormal brain function. Tracers of interest include [11C]raclopride (dopamine D2 antagonist used to study striatal dopamine function), [18F]fallypride (DA D2 antagonist, permits study of extrastriatal DA systems), [11C]PIB (marker for amyloid deposition), and [11C]DAA1106 (binds to the peripheral benzodiazepine receptor, a marker of neuroinflammation).
Dr. Yoder and her collaborators were the first to directly demonstrate that human striatal dopamine (DA) levels change during positive and negative prediction error conditions, confirming previous electrophysiology studies in animals. They have also shown that cognitive state affects striatal DA D2 receptor availability. Recently published work described a method for quantitating alchohol-induced changes in DA levels that does not require subjects to have anatomically identical responses. Dr. Yoder has extramural and intramural funding for several projects, which include: determination of the test-retest reliability of a spatially independent method for quantitating human striatal DA responses to alcohol; evaluating the extrastriatal DA system in alcoholics; and assessing the extrastriatal DA response to motor and cognitive tasks in healthy humans. Additional pilot studies will compare striatal DA tone between chronic cannabis users and healthy controls, and will examine if naltrexone (a drug used to treat alcoholism) affects the DA system in alcoholics. Upcoming studies will characterize the DA response to negative prediction error in social drinkers and alcoholics, test the effects of naltrexone on DA prediction error response in alcoholics, and assess the DA system in fibromyalgia. Dr. Yoder works closely with Dr. E. Morris on development of methods that will recover the temporal dynamics of neurotransmitter release using PET (ntPET), and with Dr. D. Kareken, who studies DA with respect to sensory cues involved in addictive processes. Dr. Yoder is also helping to develop several collaborative projects within the Center for Neuroimaging, including: determining the role of DA in metacognition in schizotypal syndromes; discerning the roles of neuroinflammation and amyloid deposition in traumatic brain injury (TBI) in humans and in animal models of TBI; and development of small animal PET imaging paradigms to longitudinally assess neuroinflammation and amyloid deposition in transgenic mouse models of neurodegenerative disorders.
Yoder KK, Kareken DA, Morris ED (2008). What were they thinking? Cognitive states may influence baseline [11C]raclopride binding potential in the striatum. Neuroscience Lett 430:38-42.
Constantinescu CC, Yoder KK, Kareken DA, Bouman CA, O'Connor SJ, Normandin MD, Morris ED. (2008) Estimation from PET data of transient changes in dopamine concentration induced by alcohol: Support for a non-parametric signal estimation method. Physics in Medicine and Biology [in press].
Yoder KK, Constantinescu CC, Kareken DA, Normandin MD, Cheng T-E, O'Connor S, Morris ED. (2007) Heterogeneous effects of alcohol on dopamine release in the striatum: A PET Study. Alcoholism: Clin Exp Res 31(6):965-973.
Morris ED, Yoder KK. (2006) PET Displacement Sensitivity: Predicting Binding Potential Change for PET Tracers Based on their Kinetic Characteristics. Journal of Cereb Blood Flow Metab 27(3):606-17.
Yoder KK, Kareken DA, Seyoum RA, O'Connor SJ, Wang C, Zheng Q-H, Mock B, Morris ED. (2005) Dopamine D2 receptor availability is associated with subjective responses to alcohol. Alcoholism: Clin Exp Res 29(6):965-970.
Morris ED, Yoder KK, Wang C, Normandin MD, Zheng QH, Mock B, Muzic RF, Jr., Froehlich JC. (2005) ntPET: A new application of PET imaging for characterizing the kinetics of endogenous neurotransmitter release. Molecular Imaging 4(4):473-489.
Yoder KK, Wang C, Morris ED. (2004) Change in binding potential as a quantitative index of neurotransmitter release is highly sensitive to relative timing and kinetics of both the tracer and the endogenous ligand. J Nucl Med 45:903-911.