Christopher D. Kroenke
In the normally-developing human brain, neurons begin to form functional circuits during the second half of gestation. This process can be disrupted by exposure to environmental insults such as alcohol, by premature birth, or as an effect of a genetically-based neurodevelopmental disorder. In many cases, resulting behavioral and cognitive deficits are not detected until childhood – a time that is too late to offer effective therapeutic intervention. In order to successfully combat disorders associated with abnormal brain maturation, it is essential to develop methodology that can closely monitor anatomical changes throughout gestation, can be used to detect abnormal patterns of development as early as possible, and can provide opportunities to assess responsiveness to therapy.
Research in the Kroenke lab utilizes magnetic resonance imaging (MRI) techniques to characterize cellular-scale anatomy. Neurons of the early-developing cerebral cortex transform from simple, elongated structures to complex, interconnected and structurally interdigitated irregular structures. An MRI technique termed diffusion tensor imaging (DTI) is sensitive to this anatomical transition. Specifically, anisotropy in water diffusion within the cerebral cortex decreases with maturation. The Kroenke lab has characterized a highly consistent temporal and regional pattern in the loss of diffusion anisotropy with age within several species (the pattern observed in baboon is shown at the left). These observations suggest that an evolutionarily conserved sequence for microstructural organization of the developing cerebral cortex underlies observed DTI patterns. Ongoing research is directed toward developing a theoretical framework to understand the relationship between DTI measurements and morphological properties of neurons. Experiments are also underway to determine how environmental factors, such as exposure to an altered maternal intrauterine environment, or alterations in experience, influence DTI measurements through perturbations to normal anatomical development. In order to make this non-invasive approach feasible for characterizing human brain development, research is also being conducted to optimize measurements of fetal brain development in utero.
Members of the Kroenke lab are also utilizing the non-invasive nature of MRI research to investigate neuroanatomical changes associated with aging, and neuroadaptive changes in adult brain following chronic exposure to alcohol. The long-term goals of these studies are to relate changes in the structure and composition of neuronal and oligodendroglial membranes to characteristics of MRI and magnetic resonance spectroscopy measurements.
Christopher Kroenke is an Associate Scientist in the Division of Neuroscience, Associate Scientist in the OHSU Advanced Imaging Research Center, and Assistant Professor in the OHSU Department of Behavioral Neuroscience. He received his PhD in the Department of Biochemistry and Molecular Biophysics at Columbia University in 2000. This was followed by a postdoctoral fellowship in the Washington University Department of Radiology. Dr. Kroenke was an Assistant Professor of Radiology at Washington University when he was appointed to the Center in 2006.
Leigland LA, Ford MM, Lerch JP, Kroenke CD. (2013) The influence of fetal ethanol exposure on subsequent development of the cerebral cortex as revealed by magnetic resonance imaging. Alc Clin Exp Res. 2013 Feb 26. doi: 10.1111/acer.12051. [epub ahead of print].
Rohlfing T, Kroenke CD, Sullivan EV, Dubach MF, Bowden DM, Grant KA, Pfefferbaum A. (2012) The INIA19 template and NeuroMaps atlas for primate brain image parcellation and spatial normalization. Front Neuroinfom. 6:Article 27.
Olavarria JF, Bock AS, Leigland LA, Kroenke CD. (2012) Deafferentiation-induced plasticity of visual callosal connections: Predicting critical periods and analyzing cortical abnormalities using difussion tensor imaging. Neural Plasticity. 2012:250196.
Jespersen SN, Leigland LA, Cornea A, Kroenke CD. (2012) Determination of Axonal and Dendritic Orientation Distributions within the Developing Cerebral Cortex by Diffusion Tensor Imaging, IEEE Trans. Med. Imaging, 31:16-32.