FUNCTIONAL LATERALIZATION OF THE PREFRONTAL CORTEX DURING TRADITIONALFRONTAL-LOBE TASKS

We attempted to identify brain regions functionally lateralized during cognitive tacks traditionally linked to the prefrontal cortex (PFC) b y measuring regional cerebral blood flow with (H2O)-O-15 positron emis sion tomography (PET). Fourteen normal subjects were scanned six times while performing six different cognitive conditions comprising three task paradigms putatively sensitive to PFC integrity: the Wisconsin Ca rd Sort (WCS), Delayed Response Alternation (DA), and the Spatial Dela yed Response (SDR) Tasks, and three matched sensorimotor control tasks . Multivariate and repeated measures analyses indicated that for all t hree cognitive paradigms there were no significant hemisphere, hemisph ere-by-condition, or hemisphere-by-region effects. However with move l iberal statistical comparison (paired t tests), the superior frontal g yrus showed lateralization during both the WCS and SDR tasks (both R > L). These results suggest that, although some asymmetries may be foun d using liberal analyses, there is less evidence of lateralized brain function during performance of these tasks of PFC function, than in la nguage and motor systems. Implications for testing PFC function in neu ropsychiatric groups are discussed.