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Scientists use Flashes of Light to Investigate Memory

If you’ve seen the Men in Black movies, you might remember the neuralyzer – the flashy thing the agents use to wipe memories? Well this might make you remember. Researchers at the University of California have just used flashes of light to find new evidence about how the brain stores memories.

What were they looking for?

Dr. Brian Wiltgen and Kazumasa Tanaka – a graduate student – were trying to investigate how the brain stores memories. It’s thought that one specific region of the brain – the hippocampus – is what triggers memory recall.

What did they find?

Their study supported their hypothesis. “Our study demonstrates that memory is retrieved when the hippocampus reinstates patterns of cortical activity that were observed during learning,” said Dr. Wiltgen in an email.

How did they do it?

To do this study, the researchers created genetically modified mice that did two specific things. First, their brain cells would light up like Christmas lights when activated by a memory. Secondly, the scientists could also temporarily de-activate cells.

The researchers then tested their hypothesis. If the mice were stimulated to remember a scary event in their past (in this case, an electric shock) they normally froze and their brain cells would light up. However, if the researchers turned off hippocampus cells, the brain cells never lit up and the mice didn’t freeze.

So?

It means that the mice didn’t recall that memory.

They forgot?

Not quite. The memory was still there – the brain cells were still there, after all – they just weren’t able to access it. Without the hippocampus to act like a key, the memory was locked away.

What does this mean?

In an email, Dr. Wiltgen said, “The hope is that once we figure out how these processes work we will be better able to understand (and treat) human disorders that affect memory.”

One caveat of this study is that the research was specifically looking at what’s known as episodic memories – memories of people, places, and events. It’s thought that other types of memory – such as skills or languages – might be controlled differently.

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Posted by on October 20, 2014 in Medicine, Natural History

 

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Shackleton’s Third Man

“She’s going down!” the men yelled, scrambling away. Their ship, The Endurance, was sinking. Antarctic ice had entrapped her for more than ten months and finally, on the 21st of November, 1915, she slipped away for good. The expedition’s leader, Sir Ernest Shackleton, was forced to watch as his men’s last connection with the civilized world disappeared underneath the stark polar ice. Stuck on the winter ice pack, Shackleton could do little but order his twenty-seven men to march for the nearest land, Elephant Island, over 300 miles away. And even after they reached solid land, the nearest civilization was little more than a scattering of whaling stations on the island of South Georgia, another 800 miles distant.

Shackleton didn’t hide from the hard truth. If they were to save themselves, South Georgia would have to be their goal. Choosing a handful of skilled men to accompany him, Shackleton sailed, rowed, and hiked the last 800 miles. He survived starvation, frostbite, and polar hurricanes, but found the whalers and returned to Elephant Island four months later to rescue those left behind.

Save your Scotts and Roald Amundsen’s. I can think of nothing that embodies the spirit of polar exploration, in all its grim determination, boundless hope, and humanity more than the story of Shackleton’s hardship. Shackleton recorded his experience in the book South: The Endurance Expedition.

But South doesn’t just represent the explorer’s spirit, hidden within its pages is an evolutionary puzzle. This book, in fact, presents one of the first recorded instances of a bizarre psychological phenomenon known as the Third Man Factor. Read:

“When I look back at those days,” writes Shackleton, “I have no doubt that Providence guided us, not only across those snow fields, but across the storm-white sea… I know that during that long and racking march of thirty-six hours over the unnamed mountains and glaciers of South Georgia it seemed to me often that we were four, not three. I said nothing to my companions on the point, but afterwards Worsley said to me, ‘Boss, I had a curious feeling on the march that there was another person with us.’ Crean confessed to the same idea. One feels ‘the dearth of human words, the roughness of mortal speech’ in trying to describe things intangible, but a record of our journeys would be incomplete without a reference to a subject very near to our hearts.”

***

The Third Man Factor is that feeling Shackleton describes, an unseen spirit or companion. Its often seems to happen to explorers and travelers who have reached the grimmest peaks of desperation. The mountain climber Reinhold Messner, aviator Charles Lindbergh, and the geologist Stephanie Schwabe all reported feeling a friendly and comforting figure guiding them out of impossible situations. Thousands of others have experienced it as well. Some have attributed to divine intervention or guardian angels.

Biologically, this poses an interesting question. It doesn’t seem to be a fluke – why should this one particular phenomenon crop up again and again in perilous situations? It could be dismissed as hallucinations or delirium, but if it was, why do the affected continue to maintain their grip on reality? Why don’t they fall into flights of fancy? Why are the visitors universally helpful? And why did every single one of Shackleton’s men all feel their phantom companion?

The answer may be a behavioral switch, long-buried in our own psyches. Scientists in Switzerland have replicated this same phenomenon by electrically stimulating the temporo-parietal junction of an epileptic woman. The junction is part of the brain that organizes sensory information. When they activated the switch, the woman became convinced of a benevolent, calming presence. When the switch was turned off, the spirit disappeared.

It’s been suggested that some of our emotional idiosyncrasies may actually be naturally evolved tools. An article from Scientific American points out that depression makes us self-reflective, analytical, and cautious in stressful situations, exactly the qualities you might want if your life was on the line. Perhaps the Third Man is another one of these evolutionary tools, a self-created guide for the conscious mind through the worst of hardships, pointing out advice that we had always known and simply forgotten.

If this is true I have a hard time thinking of anything more beautiful than a creature evolved to invent angels.

***

After the Endurance expedition, Ernest Shackleton went home to England and volunteered to serve in World War I. In 1921 he returned to exploration, but suffered a fatal heart attack less than a year later. He was buried on South Georgia island.

Of the crew the Endurance left stranded on Elephant Island, Shackleton did not lose a single man. All survived.

Sources: Dailymail.co.ukSouth: The Endurance Expedition, by Ernest Shackleton, Wikipedia

 
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Posted by on July 29, 2012 in Anthropology, Biography, History, Modernity

 

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Call No Man Happy

What measure is a disorder? Twenty years ago the esteemed psychologist R. P. Benthall submitted an interesting thought experiment to the Journal of Medical Ethics. He argued that, alongside depression and schizophrenia, the emotion commonly known as happiness could be (and should be) considered a psychiatric disorder.

Sick, sick people.

According to popular thought, a disorder is characterized by a derangement of normal behavior, characterized by discrete groups of symptoms, that may be traced back to a aberrant biological process. And, well, happiness does fit these definitions. Happy people have trouble being realistic and trouble remembering negative events in their past. They’re more likely to overestimate their abilities and control. They often display spontaneous, unpredictable behavior. Plus, we know that happiness can be biologically stimulated.

“Just as it is possible,” says Bentall, “to elicit schizophrenic symptoms in some individuals by stimulating the parietal lobes, so too it is possible to produce happiness by brain stimulation… both left hemisphere seizures and right hemispherectomy have been associated with prolonged euphoric states.”

Bentall does consider possible objections, including the fact that happiness is not normally considered a cause for medical concern and that most people, in fact, seek it out and want to be happy. “However” says Bentall, “[these objections are] dismissed as scientifically irrevelant.” He goes on to recommend the construction of ‘happiness clinics’ and ‘anti-happiness medication’.

Bentall is, of course, being tongue in cheek, but does so in a masterful way, poking some subtle fun at his own profession. If you like scientific papers I’d highly recommend it. It’s available online at the NCBI.

 
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Posted by on June 10, 2012 in Medicine, Modernity

 

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Empty Headed

Koalas do not seem to lead very complicated lives. A dog, sure. Falcon? I could see that. What with the flying and everything. And I’d bet the day-to-day life of a whale is just as complex as our own. Perhaps they even take time to see a therapist once in a while. But koalas, no, I cannot picture them as being victims of questions unanswerable nor of being one of the great creative minds of the animal world. They seem content to sit in a eucalyptus tree and eat and sleep.

Perhaps, then, I shouldn’t be surprised to learn that koalas are not especially gifted in the brain department. In fact, their brain is so small that it only makes up about 0.2% of their body mass (A human brain takes up about 2.5%), and not only that, it doesn’t even fill the whole skull. About 40% of the space between their ears is full of cushioning cerebrospinal fluid.

Interestingly, this brings up some very complicated questions. For one thing, why is the skull full of fluid? Some scientists suggested that it was actually an adaptation to prevent brain trauma during falls, but this isn’t widely accepted. It’s much more likely that it simply fills the space left behind in the head. Brain matter is very expensive to maintain and having too much of it puts a strain on the animal’s energy supplies. Koalas would need to be especially careful since eucalyptus leaves give very little nutrients.

But this raises the further question of why even keep a head two sizes too big for the brain? The answer is that it probably doesn’t pose a real evolutionary disadvantage for the animal. If an overly large head reduced their fitness, we’d expect it to eventually be removed from the population, but for koalas, this size is probably the perfect balance of weight, mass, and volume. Neutral traits are often left untouched by evolution.

Finally, perhaps the most prominent question, does this make koalas dumb? Well, yes and no. The two scientists who discovered this thought that it might make the animals slow and clumsy. But while koalas do seem to spend most of their time lazing about, they have no problem moving quickly when they need to. Instead, it seems that this lack of gray matter affects their ability to learn and adapt more than anything else. They only eat one food and only do so in a certain manner. They won’t even touch eucalyptus leaves unless they’re still on the branch. Their lives are one of routine and adaptability simply isn’t a terrible concern for them.

This koala has nothing to say on the matter.

It would seem that the first impression is correct after all. The life of a koala is a simple one. And while other animals may need quick wits or clever plans in order to tackle the problems of everyday life, one could say that the only question a koala needs to answer is: Nap? Or no?

Sources: The Koala: Natural History, Conservation, and Management, The Animal FilesNational Geographic

 
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Posted by on April 8, 2012 in Natural History

 

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