The Journal of Neuroscience, August 22, 2007, 27(34):9181-9191; doi:10.1523/JNEUROSCI.1588-07.2007
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Behavioral/Systems/Cognitive
High-Resolution Maps of Real and Illusory Tactile Activation in Primary Somatosensory Cortex in Individual Monkeys with Functional Magnetic Resonance Imaging and Optical Imaging
Li M. Chen,1,2,3
Gregory H. Turner,1
Robert M. Friedman,3
Na Zhang,1,5
John C. Gore,1,2,5,6,7
Anna W. Roe,3 and
Malcolm J. Avison1,2,4
1Institute of Imaging Science and 2Departments of Radiology and Radiological Sciences, 3Psychology, 4Pharmacology, 5Physics and Astronomy, 6Biomedical Engineering, and 7Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232
Correspondence should be addressed to Dr. Malcolm J. Avison, Vanderbilt University Institute of Imaging Science, 1161 21st Avenue South, MCN AA-1105, Nashville, TN 37232. Email: calum.avison{at}vanderbilt.edu
Although blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has been widely used to explore human brain function, questions remain regarding the ultimate spatial resolution of positive BOLD fMRI, and indeed the extent to which functional maps revealed by positive BOLD correlate spatially with maps obtained with other high-spatial-resolution mapping techniques commonly used in animals, such as optical imaging of intrinsic signal (OIS) and single-unit electrophysiology. Here, we demonstrate that the positive BOLD signal at 9.4T can reveal the fine topography of individual fingerpads in single-condition activation maps in nonhuman primates. These digit maps are similar to maps obtained from the same animal using intrinsic optical imaging. Furthermore, BOLD fMRI reliably resolved submillimeter spatial shifts in activation in area 3b previously identified with OIS (Chen et al., 2003) as neural correlates of the "funneling illusion." These data demonstrate that at high field, high-spatial-resolution topographic maps can be achieved using the positive BOLD signal, weakening previous notions regarding the spatial specificity of the positive BOLD signal.
Key words: fMRI; optical imaging; primate; somatosensory cortex; digits; topography
Received Jan. 11, 2007;
revised July 11, 2007;
accepted July 12, 2007.
Correspondence should be addressed to Dr. Malcolm J. Avison, Vanderbilt University Institute of Imaging Science, 1161 21st Avenue South, MCN AA-1105, Nashville, TN 37232. Email: calum.avison{at}vanderbilt.edu
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