Post-traumatic stress disorder (PTSD,创伤后应激障碍) is a mental disorder that develops among people who have experienced or observed traumatic things such as wars, disasters or other violent events. At the heart of PTSD is a memory that can not be controlled. It can affect the everyday lives of its sufferers in forms such as flashbacks, nightmares and anxiety.

A new study done by researchers from Yale University and the Icahn School of Medicine at Mount Sinai in New York City suggests that patients with PTSD process their traumatic memories differently than regular memories.

The researchers did brain scans of 28 PTSD patients. They asked the patients to listen to recorded narrations of their own memories. Some of the recorded memories were neutral, some were simply “sad”, and some were traumatic.

They found that when the patients listened to the “sad” memories, the hippocampus (海马体), which is responsible for forming memories, was activated. But when they listened to the traumatic memories, a different area, called the posterior cingulate cortex (PCC,后扣带回皮质), was engaged. The PCC is not a memory region. Instead, it regulates internal experiences, such as daydreaming.

The more severe PTSD symptoms are, the more active the PCC is. “The brain doesn’t look like it is in a state of memory; it looks like it is in a state of present experience,” Daniela Schiller, one of the authors of the study, told The New York Times. That means people with PTSD feel as though they’re experiencing the traumatic event again in the present moment, rather than thinking back on it like a typical memory.

The new finding might hold hope for new PTSD therapies (治疗). Future therapies are expected to focus on helping PTSD patients return their traumatic memories to the hippocampus so that they can treat them as regular and non-disruptive (非破坏性的) memories. Changing the ways of thinking could help the brain reduce the feeling of immediate threat caused by trauma, according to Ilan Harpaz-Rotem, one of the paper’s authors.

The common cold is the world’s most widespread illness, which is probably why there are more myths about it than any of the other illnesses.

The most widespread mistake of all is that colds are caused by cold. They are not. They are caused by viruses passing on from person to person. You catch a cold by coming into contact. directly or indirectly, with someone who already has one. If cold causes colds, it would be reasonable to expect the Eskimos to suffer from them forever. But they do not. And in isolated Arctic regions explores have reported being from colds until coming into contact again with infected people from the outside word by way of packages and mails dropped from airplanes.

At the Common Cold Research Unit in England, volunteer took part in experiments in which they gave themselves to the discomforts of being cold and wet for long stretches of time. After taking hot baths, they put on bathing suits, allowed themselves to be doused with cold water, and then stood about dripping wet in drafty rooms. Some wore wet socks all day while others exercised in the rain until close to exhaustion. Not one of the volunteers came down with a cold virus was actually dropped in his nose.

If cold and wet have nothing to do with catching colds, why are they more frequent in the winter? In spite of the most painstaking research, no one has yet found the answer. One explanation offered by scientist is that people tend to stay together indoors more in cold weather than at other times, and this makes it easier for cold viruses to be passed on.

No one has yet found a cure for the cold. There are drugs and pain suppressor such as aspirin, but all they do is to relieve the symptoms.