THE NEUROPSYCHOLOGY OF THE PREFRONTAL CORTEX

Single photon emission computed tomography with the xenon inhalation t echnique is used to compare activation of regional cerebral blood flow in frontal brain regions during the performance of four widely used n europsychological tests: the Continuous Performance Test, the Wisconsi n Card Sorting Test, the Tower of London, and Porteus Mazes. Healthy n ormal volunteers performing these tasks show significant increases in frontal regions during the Continuous Performance Test, the Wisconsin Card Sorting Test, and the Tower of London, but not the Porteus Mazes. Activation produced by the Continuous Performance Test and the Tower of London are mesial and bilateral and may reflect stimulation of midl ine attentional circuits. The Wisconsin Card Sorting Test produces a l eft dorsolateral area of prefrontal activation. These findings indicat e that regional activation of the frontal lobes occurs in response to cognitive challenges produced through performance of standard neuropsy chological tests.