In Brief

• Using a cell phone increases brain metabolism in the regions directly next to the phone’s antenna, according to research led by Nora D. Volkow, PhD, director of the National Institute on Drug Abuse. Volkow and colleagues observed 47 participants undergoing PET scans with cell phones strapped to each ear. The participants went through two scans: one with the phones turned off and another with the phones on and receiving a call from a recorded message (though the phones’ receivers were silent, so as to avoid auditory stimulation). While overall brain metabolism remained consistent, the areas immediately next to the cell phones’ antennae — the orbitofrontal cortex and the temporal pole — showed a 7 percent uptick in activity. It’s too early to say whether such a change is harmful in any way, Volkow says, since those levels of activity are also seen during normal brain function. (Journal of the American Medical Association, Vol. 305, No. 8)

• Dating a man with a deep voice could leave some women anxious over his fidelity, according to research by Jill O’Connor, a behavioral neuroscience graduate student at McMaster University. O’Connor recruited about 100 men and women to listen to audio clips from nine male and nine female voices. To control for reactions to verbal content, the clips were edited so that the participants only heard the speakers’ vowel sounds. When asked a series of questions about what they thought about the speakers’ relationship qualities, men and women equally picked out the higher-pitched female voices as more attractive and likely to cheat on their partners. But women were far more likely than men to point to the lower-voiced male speakers as probable cheaters. O’Connor suggests this could be because deep male voices indicate high levels of testosterone, which may be linked to infidelity. (Evolutionary Psychology, Vol. 9, No. 1)

• Brain imaging of people addicted to cocaine might reveal whether they’ll respond to a behavioral intervention, find Columbia University Medical Center researchers. The scientists ran PET scans on 22 men and three women who were dependent on cocaine. Previous research has shown that PET scans can reveal super-charged dopamine signaling in the limbic striatum, which indicates cocaine-seeking behavior. Then the researchers treated the participants with behavioral therapy that used positive reinforcement techniques to swap out drug-seeking behavior for personal goal-seeking behavior. The researchers found that people with low levels of dopamine signaling were more resistant to the treatment than were those with high levels. The findings might one day help clinicians figure out which types of therapy will work better with individual clients. (In press in the American Journal of Psychiatry)

• People who are found incompetent to stand trial are more likely than their peers to be unemployed, to have a mental disorder or to have been admitted to a psychiatric hospital, according to a meta-analysis by John Jay College of Criminal Justice psychologist Gianni Pirelli, PhD. The analysis covers more than 50 years of research and includes data from 68 studies comprising 26,139 people. Of those, 6,428 people were found incompetent to stand trial by the court, based on their ability to consult with their lawyer with a “reasonable degree of rational understanding.” Looking at the demographics of the samples, Pirelli found that compared with those who were found competent, those found incompetent were slightly older, tended to be non-white, unmarried, unemployed and diagnosed with a psychiatric disorder. This information will be useful in understanding which defendants the current definition of competency is excluding. (Psychology, Public Policy, & Law Vol. 17, No. 1)

• Bosses look more favorably upon humble, honest employees, according to Baylor University researchers. The psychologists examined supervisors’ employee ratings of 269 people working in the health-care industry at 25 different companies and surveyed the employees on a variety of personal traits. The researchers found that employees who self-reported higher levels of honesty and humility — defined in the study as showing fairness, avoiding greed and being sincere and modest — had the highest employee ratings from their supervisors. This suggests that companies should put a lot of emphasis on these traits when hiring employees, the researchers say. (Personality and Individual Differences, Vol. 50, No. 6)

• Girls who befriend boys much earlier than their peers might be more likely to abuse drugs and alcohol later in adolescence, according to researchers at the University of Quebec at Montreal. Throughout young childhood, boys and girls tend to stick to same-sex friendships. Around early adolescence, they begin to form friendships with members of the opposite sex. The researchers annually surveyed 400 boys and girls ages 12 to 18, asking them about their peer relationships and their experiences with alcohol and drugs. They found that girls who were among the earliest to branch out into opposite-sex friendships were more likely than girls who delayed such friendships to abuse alcohol and drugs later in adolescence. This relationship wasn’t seen among the boys in the study. (In press in the Journal of Research on Adolescence)

• Building rapport with witnesses can help police obtain more accurate information, according to researchers at the University of Pittsburgh at Greensburg. The team assembled 125 college-aged participants and showed them a mock-crime video of a man removing a wallet from a purse and leaving the scene. Then the researchers, acting as investigators, followed a script designed either to immediately ask questions about the crime or to build rapport first by sharing personal information about themselves and asking personal questions such as “How was your day?” or “Tell me about your family.” The participants who interacted with the friendlier investigators were better able to recall accurate details about the crime than were their peers who were simply questioned. The findings suggest that even when crunched for time, it’s important to establish rapport with witnesses, researchers say. (In press in Applied Cognitive Psychology)

• Rats that spend time together can cooperate better than those that are separated from their partners, according to researchers at the Polish Academy of Sciences in Krakow. They devised an experiment in which a pair of captive rats could simultaneously push two buttons to release sugar water. During the experiment, the researchers examined how well rats kept in various social situations would be able to cooperate to obtain the sugar water. First they trained them without any partition in the cage, then with an opaque plastic wall between the rats, then again with no partition, and finally with a wire-mesh separator. The researchers recorded how successful they were at getting the sugar water, as well as how many high-pitched vocalizations occurred between them. The rats were most successful (and most talkative) without any partition at all between them and least successful with the opaque wall, leading the researchers to conclude that rats cooperate better when they can easily socialize. (In press in the Journal of Comparative Psychology)

• A mouse model of how early-stage HIV affects the human brain indicates that the infection leads to inflammation, changes in brain cells and neuronal damage, according to researchers from the University of Nebraska Medical Center and the University of Rochester Medical Center. In the study, the researchers infected mice that had been transplanted with human blood stem cells to mirror the disease’s progression in humans. MRI readings and post-mortem examinations showed that as HIV caught hold in the mice’s immune systems, their glial cells became inflamed and their neurons showed fewer and degraded synaptic connections. Brain damage associated with early-stage HIV might even disrupt decision-making processes and encourage risky sexual behavior, furthering the spread of the disease, the researchers say. (Journal of Neuroscience, Vol. 31, No. 9)

• An enzyme called PKMzeta can enhance or erase long-term memories in rats depending on whether it’s increased or blocked in the brain, say researchers from the Wiezmann Institute of Science in Rehovot, Israel. Most biological memory enhancement techniques only work soon after neurons encode the memory, but this new technique can potentially work any time, the researchers say. They paired an overactive version of the gene that encodes the PKMzeta enzyme with a harmless virus and inserted it into the rats’ neocortices. These rats showed increased memory abilities as assessed in an operant conditioning procedure. But when the researchers injected a defective version of the gene into the rats — even those that had long-standing memories of the conditioning — they promptly forgot their training. (Science, Vol. 331, No. 6,021)

• Low birth weight can contribute to increased activity in the brain’s right hemisphere, according to researchers at the University of Southampton in England. Alexander Jones, PhD, measured temperature fluctuations of the tympanic membranes in the ears of 140 8- and 9-year-old children. Such fluctuations indicate blood flow within the brain. Comparing that data with information on the children’s birth weights, Jones found that the children born small and with large placentas were more likely than other children to have increased activity within their right hemispheres. It’s thought that poor nutrition or stress can cause growth of the placenta that is disproportionate to that of the fetus, and the consequent brain patterns might put children at a higher risk for mood disorders such as depression and anxiety, the researchers say. (Public Library of Science ONE, Vol. 6, No. 2)

• Thrill-seeking behavior might have its roots in the same brain reward system that usually reinforces pleasant experiences, say researchers at Georgia Health Sciences University. The scientists used tiny implanted brain sensors in mice to monitor dopamine-responsive neurons while they exposed the mice to one of three conditions: a short free-fall, shaking or receiving sugar water. Predictably, the dopamine-responsive neurons activated when the animals tasted sugar water, but about 25 percent of the mice’s dopamine neurons also responded to the animals being shaken or falling — something that’s counterintuitive to our understanding of the reward system. The researchers believe that the thrill of the danger itself activated the reward system, which might help explain why thrills sometimes delight us. (Public Library of Science ONE, Vol. 6, No. 2) 

—M. Price