From mind melds to 'the dress,' here's what we learned about the brain in 2015

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We learned a lot about the brain in 2015, but we still have a long way to go.

From a viral photo that changed how we see the world to discoveries about how the brain changes as we age, here are some of the biggest discoveries we made about the brain this year:

1. It's possible to create an animal "mind meld"

Star Trek fans had cause to rejoice this summer, because scientists created what some have referred to as the first "mind meld" — though some scientists say the term is exaggerated — by connecting the brains of several rats and of monkeys.

Neuroscientists at Duke University built a "Brainet" by combining the electrical signals from four rat brains using electrical recording and stimulation. They did the same thing with two monkey brains.

Together, the animals learned to solve problems such as forecasting the weather or moving a robotic arm, often performing better than a single animal alone, according to the study, published in July in the journal Scientific Reports.

We're still a ways off from the Vulcan mind meld, though, because the brain signals being sent here were still fairly rudimentary, and the experiments were in animals, not humans.

2. We see color in vastly different ways

Vimeo/JonOIn February, the Internet erupted over a photograph of a bridal dress posted on Tumblr whose color people couldn't agree on. Some saw "the dress" as white-and-gold, while others swore it was blue-and-black.

Later, three groups of scientists studied the phenomenon, and found that the disagreement has to do with how our brains perceive color in different lighting. People who saw the dress as white-and-gold probably assumed that it was in bright daylight (which is bluish), whereas those who saw it as blue-and-black may have thought it was in low or artificial light (which is yellowish).

3. There's no such thing as a "male" or "female" brain

For a long time, people assumed that men's brains were fundamentally different than those of women, but recent findings call that into question.

In a study published in November in the journal Proceedings of the National Academy of Sciences, a team of researchers looked at brain scans of 1,400 people. They divided people into male or female categories based on personality traits, activities, and other factors more commonly seen among the men or women in the study.

Anywhere from a quarter to more than a half of people had both "male" and "female" traits, which means they didn't fall into one category. Not so fast, "male" or "female" brain believers.

4. We can give sleeping mice fake memories

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We got a step closer to "Eternal Sunshine of the Spotless Mind" this year, when a team of scientists created false memories in the brains of mice while they slept, according to study published in March in the journal Nature Neuroscience.

The brain is thought to replay our daily activities while we sleep, but how this occurs remains something of a mystery.

Researchers in France implanted electrodes in the brains of 40 mice in a region involved in spatial navigation memory. Then, while the animals slept, they stimulated areas of the brain that were active when the mice were in certain locations, creating an artificial memory that the mice recalled when they were awake. Creepy.

5. The brain cleans itself

Neuroscientists have long assumed that the brain lacks a lymphatic system like the one that drains wastes out of the rest of the body.

But in July, a team of scientists published a study in the journal Nature announcing they had found evidence of lymphatic vessels in channels of the outermost layer of the meninges, the membranes that surround and protect the brain. The vessels showed all the signs of a lymphatic system, carrying immune cells and other fluid to nearby lymph nodes, which filter out waste.

The findings question some basic assumptions about immune function in the brain and diseases related to it.

5. Exercise is even more important for our brains than we thought

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Scientists are finding more and more evidence that exercise isn't only good for your body, but for your brain as well.

In December, the New York Times reported on a study in the journal Neuroimage, which measured the brain activity of 60 older adults in Japan while they completed a task that required lots of concentration.

When they compared the brain scans to those of younger adults, they found something surprising: Older adults who performed better on fitness tests had brains that looked more like those of young adults, compared with the brains of less-fit older adults. The findings add to the evidence that exercise keeps your brain younger and healthier.

6. We can make artificial brain cells

In June, a team of scientists announced they had created the first fully functional human-made neuron.

In the study, published in the September issue of the journal Biosensors and Bioelectronics, researchers built the "neurons" by connecting protein biosensors to electronic ion pumps. The resulting neurons mimicked the functions of a human brain cell, including converting chemical signals into electrical ones and communicating with other types of cells, Science Alert reported.

Ultimately, the hope is these neurons could be implanted in human brains to repair damage due spinal cord injury or diseases like Parkinson's.

7. Successful people tend to have more "connected" brains

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We're only just starting to get a handle on how our brains are wired. But the first results of a massive effort to map the connections between cells in the brains of more than 1,000 living people, known as the Human Connectome Project, sheds some light on how brain wiring and personality traits are related.

In the study, published in September in the journal Nature, researchers scanned the brains of 461 people to see which areas were active at the same time, or "functionally connected." They compared these scans with characteristics like income, education level, and drug use, as well as cognitive measures like IQ and memory.

What they found was that people with more functionally connected brains were likely to have more beneficial personality traits like high IQ, and fewer negative traits like alcoholic tendencies. Of course, while the findings are preliminary, they still tell us something interesting about our brain wiring.

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