Energy-efficient brains.

Successful problem solving depends on a brain that efficiently lessens its workload rather than laboring harder, a new study finds. Individuals may thus prefer less effortful problem-solving strategies not only for their simplicity but for their superior results, contend neuroscientist Erik D. Reichle of Carnegie Mellon University in Pittsburgh and his colleagues.

Reichle's group administered tests of visual-spatial ability and verbal ability to five men and seven women. Next, functional magnetic resonance imaging scans assessed volunteers' brain activity--as indicated by the blood flow rising and falling--as they determined whether a series of sentences that they read corresponded to images that followed each sentence. On some trials, participants were told to form a mental image of each sentence to compare with the pictures; on other trials, they were told to focus on verbal meanings of sentences.

Volunteers made few errors on this task. The imagery strategy yielded more activation in brain regions linked to visual and spatial skills. However, individuals who scored highest on visual-spatial ability exhibited markedly lower blood-flow boosts in those areas, the scientists report in the June COGNITIVE PSYCHOLOGY. The verbal strategy produced activity hikes in language-related locations. Those increases were lowest for volunteers with the best verbal skills, Reichle's group says.

The findings coincide with reports of energy-efficient brain responses to learning (SN: 4/4/92, p. 215) and of powerful but simple decision tactics (SN: 5/29/99, p. 348).