[1] Univ Calif San Diego, Dept Radiol, Ctr Funct MRI, Imaging Hardware, San Diego, CA 92103 USA
[2] NIMH, Sect Funct Imaging Methods, NIH, Bethesda, MD 20892 USA
[3] NIDA, Neuroimaging Res Branch, NIH, Bethesda, MD 20892 USA
[4] Med Coll Wisconsin, Dept Biophys, Milwaukee, WI 53226 USA
[5] NIDA, Neuroimaging Res Branch, IRP, Bethesda, MD 20892 USA
[6] Univ Wisconsin, Dept Psychiat, Madison, WI 53706 USA
[7] Med Coll Wisconsin, Dept Anesthesiol, Milwaukee, WI 53226 USA
[8] Med Coll Wisconsin, Dept Physiol, Milwaukee, WI 53226 USA
[9] Med Coll Wisconsin, Dept Biophys, Milwaukee, WI 53226 USA
[10] Cleveland Clin, Schey Ctr Cognit Neuroimaging, Cleveland, OH 44106 USA
[11] Max Planck Inst Human Cognit & Brain Sci, Dept Neurophys, Leipzig, Germany
[12] Cleveland Clin, High Field MRI, Cleveland, OH 44106 USA