A neural basis for general intelligence

Universal positive correlations between different cognitive tests motivate the concept of "general intelligence" or Spearman's g. Here the neural basi s for g is investigated by means of positron emission tomography. Spatial, verbal, and perceptuo-motor tasks with high-g involvement are compared with matched Low-g control tasks. In contrast to the common view that g reflect s a broad sample of major cognitive functions, high-g tasks do not show dif fuse recruitment of multiple brain regions. Instead they are associated wit h selective recruitment of lateral frontal cortex in one or both hemisphere s. Despite very different task content in the three high-g-low-g contrasts, Lateral frontal recruitment is markedly similar in each case, Many previou s experiments have shown these same frontal regions to be recruited by a br oad range of different cognitive demands. The results suggest that "general intelligence" derives from a specific frontal system important in the cont rol of diverse forms of behavior.