 In more direct assessments of DA receptor pharmacology, Suhara et al. 1992 reported an abnormal decrease in D1 receptor binding using 11CSCH 23390 in the frontal cortex of bipolar subjects. However, 11CSCH 23390 has some affinity for 5-HT2 receptors in the frontal cortex De Keyser et al.,1988 so the specificity of this result remains unclear. In contrast, 11CNNC 112 is selective for D1 receptors and shows sufficient receptor selectivity to access D1 receptor binding in the frontal cortex in mood disorders. 