Deep asleep? You can still follow simple commands

Scientists once considered sleep to be like a shade getting drawn over a window between the brain and the outside world: when the shade is closed, the brain stops     1     (react) to outside stimuli.

A study published on 12 October in Nature Neuroscience suggested that there might be periods during sleep when that shade is partially open. Depending on what researchers said to them, participants in the study would     2     smile or frown on cue in certain phases of sleep.

“You’re not supposed to be able to do stuff     3     you sleep,” says Delphine Oudiette, a cognitive scientist at the Paris Brain Institute in France and a co-author of the study. Historically, the definition of sleep is that consciousness of your environment stops, she adds. “It means you don’t react to the external world.”

A few years ago, however, Oudiette began questioning this definition after she and her team conducted an experiment     4     they were able to communicate with people who are aware that they are dreaming while they sleep — otherwise known as lucid dreamers. During these people’s dreams, experimenters were able to ask questions and get responses through eye and facial-muscle movements.

Karen Konkoly, who was a co-author on that study and a cognitive scientist at Northwestern University in Evanston, Illinois, says that after that paper came out, “it was a big open question in our minds     5     communication would be possible with non-lucid dreamers”.

Hence, Oudiette continued with the work. In her latest study, she and her colleagues observed 27 people with narcolepsy — characterized by daytime sleepiness and a high frequency of lucid dreams — and 22 people without the condition. While they were sleeping, participants     6     (ask) to frown or smile. All of them responded accurately to at least 70% of these prompts.

Overall response rates were higher for all participants during REM (rapid eye movement) sleep, when the deepest sleep occurs but the brain remains more active than during other sleep stages. The researchers tracked participants’ brain activity during the experiments using electroencephalography   (EEG), which captures signals from electrodes (电极) placed along a person’s scalp (头皮). What this shows was that “you have some physiological states that are     7     (favourable) to drawing the window shade than opening it to the external world”, Oudiette says.

    8     (use) similar experiments, researchers might gain a better understanding of various sleep disorders, including insomnia and sleep walking, she says. Later on, they might begin to identify the parts of the brain that are active during sleep, and how     9     relate to consciousness.

This study being conducted is part of a larger evolution in the field of sleep research, says Melanie Strauss, a neurologist and cognitive scientist at Erasmus Hospital in Brussels, Belgium. Researchers     10     (move) away from monitoring sleep mainly with EEG and towards “fine grained” approaches that combine EEG with various tasks and stimuli — a strategy that could help to shed light on specific diseases or conditions, she says.

What is Prosopagnosia?

Imagine living in a world where everyone looks vaguely familiar, but you never know for certain exactly who anyone is. Your old classmates, your coworkers, your friends, and even your family members can appear     1     first glance to be friendly strangers who seem to know you. That’s     2     life is like for people with prosopagnosia, or face blindness.

Prosopagnosia is a neurological (神经性的) disorder that causes someone to have trouble recognizing people they know, or distinguishing between different people’s faces.     3     difficulties in face recognition were noted over a hundred years ago, understanding of prosopagnosia is still unfolding. The condition has received a significant share of the public’s attention after American author Jean Gilbert penned down her struggles with prosopagnosia in her book, The Picasso Mirror.     4    , such as well-known British anthropologist Dr Jane Goodall and Hollywood actor Brad Pitt, have also revealed that they have face blindness.

A study from Harvard and University College London found that prosopagnosia may affect up to 2% of the population,     5     (mean) there may be millions of face-blind people. For many people just realising that their difficulties are the result of a recognised neurological condition and that they are “not alone”     6     (make) a huge difference.

For typical observers face recognition is based on the whole face, but for prosopagnostics is it the opposite — they are more focused on     7     (isolate) features. They often have to rely on clues other than someone’s facial features, such as hairstyle, clothing, or voice,     8     (identify) the people they know. It     9     be very disturbing for the person who has face blindness, as they do not know how to relate with people. This would hold especially true if the person isn’t aware that they might have prosopagnosia. They could become socially withdrawn,     10     could lead to depression, panic attacks, social isolation or social anxiety.