Body & Brain

Fat sensors muted in the overweight Most people can easily detect the presence of oil in foods, but the threshold for tasting this fat is only about half as high in lean men as in heavy ones, Australian scientists report. Their study of 19 men (eight lean) also monitored the recruits’ gastrointestinal responses to fat. Here as well, overweight and obese individuals proved less effective at sensing the arrival of fat and triggering appropriate hormonal feedback signals to the brain. Whether this decreased sensitivity might foster overconsumption of fat, versus the other way around, will require further testing, the scientists conclude in the April American Journal of Clinical Nutrition . — Janet Raloff LSAT test prep molds brain SAN FRANCISCO — Law school hopefuls might have empty pockets after paying big bucks for an LSAT test prep class, but their brains could very well work better. The rigorous, 100-hour long classes boost the activity of select brain regions, a change that may be partly responsible for the average 10 point gain on the LSAT people get from taking them. After training, students scored better on reasoning tests, too, Allyson Mackey of the University of California, Berkeley reported April 3 at the annual meeting of the Cognitive Neuroscience Society. Age- and IQ-matched prelaw students didn’t have this increase. It’s unclear how long the brain changes would last, Mackey said. — Laura Sanders A new itch receptor Researchers have pinpointed a protein that’s required to induce pernicious itches that can’t be stopped with antihistamine drugs such as Benadryl. Mice lacking the protein TRPA1 were impervious to several different itch-inducing agents, researchers led by Sarah Wilson of the University of California, Berkeley have found. TRPA1 is better known for its job sensing pain, but its new role in itch may be put to use: Interfering with the protein may offer a new way to treat some forms of chronic itch, the researchers report online April 3 in Nature Neuroscience . — Laura Sanders Thirsty rats get more friendly Rats that need a drink are less susceptible to social stress, a study published April 6 in the Journal of Neuroscience shows. Dehydrated rats had much higher levels of oxytocin, a hormone that aids pair bonding and social interactions. Enhancement of social behaviors when thirsty might be a good thing, researchers led by Eric Krause of the University of Cincinnati College of Medicine propose: Rats desperate for water might be less frightened of the communal watering hole. — Laura Sanders Neurons make owls take notice Barn owls are darn good at spotting a mouse scurrying through hay. Now, a study shows how the owl’s brain shifts attention from one object, like the hay, to another, like the mouse. Brain-cell switches turn on as soon as a new object outcompetes an old one for prominence in the bird’s range of vision, researchers at Stanford University report in the April 6 Journal of Neuroscience . The team showed owls videos of two dots, one growing and one shrinking. While some neurons recorded the slow changes in dot size, others lit up as soon as the growing dot overwhelmed the shrinking dot. — Daniel Strain