Asking people to perform a mental exercise while their brain activity is monitored is a technique that has enabled neuroscientists to probe the biological basis of the human mind. Research reported today has traced two familiar mental phenomena to specific locations in the brain.

One trait believed to differentiate humans from other primates is the ability to appreciate aesthetics. Scientists have suspected that such judgement stems from an area of the brain called the prefrontal cortex--one of the last cortical regions to expand dramatically over evolution---but experimental evidence has been lacking. To test this theory, a team of researchers led by Camilo J. Cela-Conde of Balearic Islands University in Spain showed pictures of art and natural photography to eight subjects, asking them to point out the pictures they found beautiful while imaging their brains using a technique called magnetoencephalography (MEG). As predicted, the task activated the prefrontal cortex. This part of the brain is generally known to play a role in different kinds of decision making, the researchers note, but their analysis further identified a specific region within the prefrontal cortex that responds when an individual deems something beautiful. The study, published online today in the Proceedings of the National Academy of Sciences, suggests that this area may be "intrinsically related to conscious aesthetic perception" and may offer tantalizing insight into how "a phylogenetic change in the prefrontal cortex could give way to the decorative and artistic profusion" in humans.

A second brain study, published online today in the journal PLoS Biology, has brought to light the area of the brain that is activated when we experience a flash of insight--the so-called "Eureka!" moment. Mark Jung-Beeman of Northwestern University and his colleagues devised a series of mental puzzles consisting of three words-- pine, crab and sauce, for example--and asked 37 subjects to come up with a fourth word that could combine with each of the three to form a compound word or phrase (in this case, apple). Subjects were instructed to press a button when they felt a sudden clarity, or "Aha!" Using functional magnetic resonance imaging and electroencephalography, the scientists mapped this experience to a distinct area in the right hemisphere of the brains temporal cortex. The temporal cortex is known to make semantic connections between different kinds of ideas, the researchers report, and putting together known concepts in novel ways might be exactly what defines an insight, Jung-Beeman suggests. "For thousands of years people have said that insight feels different from more straightforward problem solving," he says. "We believe this is the first research showing that distinct computational and neural mechanisms lead to these breakthrough moments." --Alla Katsnelson