TIME neuroscience

A ‘High’ From Marijuana Is Really the Opposite in Your Brain

Daily Life In South Africa
A youth smokes marijuana in Soweto township, near Johannesburg, on July 2, 2013 Christopher Furlong—Getty Images

Marijuana dulls your response to dopamine

A new study suggests marijuana blunts the brain’s reaction to dopamine, making users less responsive to the chemical responsible for feelings of reward and pleasure.

In the study published Monday in the journal Proceedings of the National Academy of Sciences, the researchers studied the brains of 24 marijuana abusers — that is, people who smoked multiple times a day — and how they reacted to methylphenidate, a stimulant often used to treat ADHD and narcolepsy. Using personality tests and brain imaging, the researchers found the pot users had blunted behavioral, cardiovascular and brain responses to methylphenidate compared with control participants. Marijuana abusers scored lower on tests of positive emotional activity and higher on negative emotional reactions.

The researchers believe that pot not only dampens the brains’ dopamine reaction to stimulants but also influences the area of the brain involved in reward processing. The participants had lower reward sensitivity, higher levels of irritability, and likely more depression and anxiety.

The researchers conclude that the way pot interferes with the brain may contribute to drug cravings. And that a “high” is really the opposite in the brain.

TIME neuroscience

New Technology Helps Brain Signals Move Paralyzed Hand

An innovative device sends brain signals directly to muscles, skipping over the spinal cord of the injured patient

A quadriplegic man was able to move his hand simply by willing it to happen with his mind–a medical breakthrough made possible with the help of a new device still in its testing phase.

23-year-old Ian Burkhart, paralyzed in a diving accident four years ago, was the first participant to try out a decade-in-the-making technology called Neurobridge, which sends neural signals directly to muscles.

This April, researchers planted a tiny chip that interprets brain signals into the part of Burkhart’s brain that controls hand and arm movements. The chip interprets signals from a computer and transfers them to a sleeve that stimulated Burkhart’s muscles, thereby skipping over his damaged spinal cord.

“The surgery required the precise implantation of the micro-chip sensor in the area of Ian’s brain that controls his arm and hand movements,” said Dr. Ali Rezai, one of the clinicians leading the trial.

Part of a clinical trial at Ohio State University’s Wexner Medical Center, in collaboration with technology development company Battelle, researchers hope that Neurobridge could become a future aid for many patients impacted by spinal cord injuries or traumatic cerebral events like strokes.

TIME

Sleep Helps You Remember Things If You’re a Mouse

That’s the technique that worked best for mice in an intriguing study on how sleep helps the brain to create and store memories

It’s hard to tell how much a mouse remembers, but by peering at the activity of nerve cells in animals’ brains while they sleep, researchers have found some clues. That’s how Wen-Biao Gan, a neuroscientist and physiologist at New York University, learned some interesting things about what happens when mice snooze.

By tagging nerves cells in their brains, Gan and his colleagues report in the journal Science that sleep is actually a very active time for the brain, in which connections between buzzing nerve cells are made in order to consolidate memories. The researchers had mice run on a rotating and accelerating rod, then allowed them to sleep. Some of the mice got to slumber undisturbed, while others were handled to keep them from getting quality sleep. The animals who slept undisturbed showed signs of new neural connections forming during just the first phases of sleep, known as non REM sleep.

“My feeling is that sleep is important to the process of forming long term memory,” says Gan. During REM, not only are the same nerve connections that the mice made while they ran reactivated, but new connections were also made. When he blocked the reactivation of nerves, no new connections were made, suggesting that learning, or making long term memories, is a two part process in which sleep plays an important role.

How applicable are these findings to helping people? Hopefully some of same principles apply, says Gan, although more studies will be needed to confirm that. So don’t underestimate how much work your brain is doing while you catch some z’s. Most of what you remember could be thanks to getting a good night’s sleep.

TIME psychology

Be More Productive—By Doing Less

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Reza Estakhrian—Getty Images

Our constant busyness prevents us from entering the associative mental state in which unexpected connections and insights are achieved.

“Leisure is the new productivity.”

That counterintuitive slogan emerged from a panel I attended last week at the annual conference of the New America Foundation, a Washington D.C. think tank where I am fortunate to be a fellow. The panel was anchored by Brigid Schulte, a Washington Post reporter and the author of a new book, Overwhelmed: Work, Love and Play When No One Has the Time.

Time and the way we spend it was Schulte’s focus, and she argued that we spend too much time working, logging more hours at the office than employees in any other developed country save Japan and South Korea. As a result, “we have a lot of unproductive, sick, unhappy, burned out, and disengaged workers,” Schulte noted. Ironically, we are less productive, creative, and innovative than we would be if we had more time off.

Our continual state of busyness, she explained, prevents us from entering the loose, associative mental state in which unexpected connections and aha! insights are achieved. Schulte was drawing here on the research of psychologists and neuroscientists, one of whom, Northwestern University professor Mark Beeman, was also on the panel.

Beeman and his collaborators have found that although we may appear idle while daydreaming or mind wandering, the brain is actually working especially hard in these moments, tapping a greater array of mental resources than are used during more methodical thinking. This unfocused “default mode,” Schulte has written, “is like a series of airport hubs in different and typically unconnected parts of the brain.” When activated, it “puts together stray thoughts, makes seemingly random connections and enables us to see an old problem in an entirely new light.”

If we don’t allow our minds to have this kind of downtime—because we’re always under stress and on deadline, always making calls and checking email—such connections and insights won’t materialize. “At work and at school, we expect people to pay attention, to focus,” Beeman observed. “To focus on one thing, you have to suppress a lot of other things. Sometimes that’s good. But sometimes a solution to a problem can only come from allowing in apparently unrelated information, from giving time to the quieter ideas in the background.”

Schulte and Beeman contend that we need to make room in our lives for two distinctly different kinds of mental activity: the directed, focused attention usually expected of us at work and at school, but also a more diffuse and leisurely state in which we’re focusing on nothing in particular. “Oscillating” between these two modes—a kind of interval training for the mind—is the best way to reap the benefits of both kinds of thought.

“As we move ever further into a knowledge economy, in which ideas are our products, we have to think about where ideas come from,” Schulte concluded. Where they come from, she argued persuasively, is not only from conventional work, but from productive leisure.

Annie Murphy Paul is the author of the forthcoming book Brilliant: The Science of How We Get Smarter. Read more at her blog, where this post first appeared.

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