Although it may sound counterintuitive, loneliness can spread from one person to another, according to research being released Tuesday that underscores the power of one person’s emotions to affect friends, family and neighbors.

The federally funded analysis of data collected from more than 4,000 people over 10 years found that lonely people increase the chances that someone they know will start to feel alone, and that the solitary feeling can spread one more degree of separation, causing a friend of a friend or even the sibling of a friend to feel desolate.

“Loneliness can be transmitted,” said John T. Cacioppo, a University of Chicago psychologist who led the study being published in the December issue of the Journal of Personality and Social Psychology. “Loneliness is not just the property of an individual. It can be transmitted across people — even people you don’t have direct contact with.”

“People can’t multitask very well, and when people say they can, they’re deluding themselves,” said neuroscientist Earl Miller. And, he said, “The brain is very good at deluding itself.”

Miller, a Picower professor of neuroscience at MIT, says that for the most part, we simply can’t focus on more than one thing at a time.

What we can do, he said, is shift our focus from one thing to the next with astonishing speed.

“Switching from task to task, you think you’re actually paying attention to everything around you at the same time. But you’re actually not,” Miller said.

“You’re not paying attention to one or two things simultaneously, but switching between them very rapidly.”

Miller said there are several reasons the brain has to switch among tasks. One is that similar tasks compete to use the same part of the brain.

“Think about writing an e-mail and talking on the phone at the same time. Those things are nearly impossible to do at the same time,” he said.

“You cannot focus on one while doing the other. That’s because of what’s called interference between the two tasks,” Miller said. “They both involve communicating via speech or the written word, and so there’s a lot of conflict between the two of them.”

Researchers say they can actually see the brain struggling. And now they’re trying to figure out the details of what’s going on.

How does an actor engage with the part they are playing? Fiona Shaw undergoes a brain scan while reciting TS Eliot to help shed some light on the mystery.

Nagging doubts, compulsions, concerns of contamination, obsessive hoarding: the symptoms of obsessive compulsive disorder are numerous and varied. What is it like to live this way? How does one maintain a normal life? Six men and women speak about their battles with this disorder.

The great promise of neuroscience at the end of the last century was that it would revolutionize the treatment of psychiatric problems. But the first real application of advanced brain science is not novel at all. It is a precise, sophisticated version of an old and controversial approach: psychosurgery, in which doctors operate directly on the brain.

In the last decade or so, more than 500 people have undergone brain surgery for problems like depression, anxiety, Tourette’s syndrome, even obesity, most as a part of medical studies. The results have been encouraging, and this year, for the first time since frontal lobotomy fell into disrepute in the 1950s, the Food and Drug Administration approved one of the surgical techniques for some cases of O.C.D.

While no more than a few thousand people are impaired enough to meet the strict criteria for the surgery right now, millions more suffering from an array of severe conditions, from depression to obesity, could seek such operations as the techniques become less experimental…