Reciprocal Lateralization of Frontal Lobe Functions

In the January 1994 issue of the Archives, Rauch et al¹ report the relationship between regional cerebral blood flow (rCBF) and obsessive-compulsive symptoms measured by the Obsessive-Compulsive Disorder [OCD] Analogue Scale (OCDAS). In a provoked OCD state, OCDAS scores were positively correlated with left orbitofrontal rCBF and negatively correlated with right orbitofrontal rCBF. Rauch et al conclude that "... these two regions may play opposing roles in mediating and suppressing OCD symptoms respectively."

These OCD findings strongly resonate with our own findings in patients with lateralized focal frontal lesions.² We have designed an inherently ambiguous cognitive activation procedure, the Cognitive Bias Task (CBT). A high CBT score indicates a context-dependent, internally driven behavior; and a low score, contextindependent, externally driven behavior. The CBT scores of healthy controls are in the middle of the scale, suggesting a balanced response selection strategy. Lateralized frontal lesions produced extreme deviations of CBT scores