research

Study: Teens' View of Fairness Shifts as Brain Develops

September 20, 2017 by Office of Public Affairs

Research links cortical thinning over time to the ability to consider others’ intentions.

When it comes to the concept of fairness, teenagers’ ability to consider the intentions of others appears to be linked to structural changes in the brain, according to a study led by Assistant Professor of Psychological and Brain Sciences Luke Chang.

The research found that cortical thinning of specific areas of the brain from youth into young adulthood corresponded to the transition from an emphasis on equality in all transitions to a more complex consideration of the intentions of others in exchanges. This developmental change in the social brain continued through late adolescence, the researchers said.

Why ‘Don’t Even Start’ Doesn’t Work With Teenagers

Researcher David Bucci flips the neural switches to replicate an “adolescent brain.”

January 10, 2017 by Bill Platt
Originally published in the Dartmouth News.

As parents of a teenager can tell you, adolescents don’t always think about risks before they act, whether it is venturing onto thin ice on a dare or spending the weekend watching an entire Star Wars marathon before starting a project that’s due Monday.

For many years psychologists and researchers have observed this behavior and linked it to data showing that the part of the brain that regulates impulsivity—the prefrontal cortex—is not yet fully developed in adolescents, while the deeper reward-seeking part of the brain, called the nucleus accumbens, develops more rapidly, leaving teens with less control over impulses.

Now Dartmouth researchers have identified and altered the precise neural circuits that control reward-seeking impulses and risk-assessment controls, effectively flipping the switches to create an “adolescent brain” in adult rats.

State-of-the-Art fMRI Brain Scanner Arrives at Dartmouth

August 29,2018 by Joseph Blumberg

Researchers are welcoming the arrival of a new fMRI scanner, the latest in a series of scanners dating back to 1999, when the Dartmouth became the first liberal arts college in the nation to own and operate a functional magnetic resonance imaging device strictly for research purposes.

The new scanner, weighing more than 26,000 pounds, was lowered into its bay beneath Moore Hall last month, in the home of the Department of Psychological and Brain Sciences (PBS).

“This is a big deal,” says James Haxby, the Evans Family Distinguished Professor and director of both the Center for Cognitive Neuroscience and the Brain Imaging Center. “We are extremely excited about getting this new scanner. It will be in use seven days a week, from early morning to late at night.”

How Imagination Works (Popular Science)

Popular Science features new Dartmouth research that focuses on what the brain’s “mental workplace” looks like when people manipulate images in their mind.

“Our lab is very interested in the kind of flexible cognitive behaviors that humans have,” Alex Schlegel, a graduate student in the Department of Psychological and Brain Sciences, and lead author of the study, tells Popular Science. “We can learn new things, we can think of new concepts, seeing things from different perspectives—a lot of this has to do with a very rich mental space, kind of a mental playground.”

Participants in the study were asked to look at pictures of abstract shapes, explainsPopular Science. While undergoing an fMRI scan, they were asked to recall or manipulate the images in their mind. “We saw differences in activity all over the brain when we compared to control conditions,” Schlegel tells the magazine. “Rather than being a single area responsible for imagining or manipulating, it seems like lots of areas have to work in concert.”

Read the full story, published 9/16/13 by Popular Science.

Familiar Faces (ScienceNews)

In a story about “super recognizers”—people who have an exceptional ability to remember faces—ScienceNews turns for comment to Dartmouth’s Bradley Duchaine.

Duchaine, an associate professor of psychological and brain sciences, and colleagues in England are studying super recognizers to understand how some people are able to recognize nearly everyone they’ve ever seen, the magazine writes. Knowledge gained from such studies may aid in police work and other fields that rely on identifying people by how they look, notes the magazine.

“By identifying strategies used by super recognizers, we may find ways to train others who have problems with face recognition, or help people who are in the normal range but have professional demands in which superior face recognition would be beneficial,” Duchaine tells ScienceNews.

Read the full story, published 8/23/13 by ScienceNews.

Scientists Identify an Off Switch for Bad Habits

What if the brain had a light switch that could be flipped to turn off a bad habit?

Research by Assistant Professor Kyle Smith, who joined the faculty of Dartmouth’s Department of Psychological and Brain Sciences last month, has found just that in lab rats. Smith and others have identified brain cells involved in habit formation and inhibition. Researchers introduced DNA for photosensitive molecules into the brain’s cortex to make specific neurons respond to light from a fiber optic implant. Then, by flashing a light on these key cells, researchers managed to abruptly halt habits and inhibit the formation of new habitual behaviors. 

Smith and his colleagues trained rats to run a maze for a reward. They then overtrained the animals so they ran the pattern even after the behavior brought negative results—in this case, food that tasted bad. So the rats continued the habit, in a sense, against their better judgment. It is not unlike a person continuing to bite his fingernails even though he wants to stop, Smith says.

Rare Disorder Leaves Woman Lost in Familiar Places

In a story about a rare disorder that makes it difficult for people to recognize even familiar places, NBC’s The Today Show interviews Dartmouth’s Jeffrey Taube, who studies the navigational processes used by rats.

Taube, a professor of psychological and brain sciences, says “the rat’s—and probably people’s—brain cells fire like a compass. There is a neuron that fires any time the rat heads north and another that fires when the rat heads south-southeast.”

When everything is working properly, he says, the brain constructs a map that allows us to find our way through familiar surroundings without needing directions.

“There’s a system that’s important for perceiving where you are, another for keeping track of where you are heading and another for keeping track of the distance you’ve moved,” he tells The Today Show. “Any one of these without the others won’t do you any good.”

Read the full story, published 5/13/13 by The Today Show.

Neuroscientist Says Humans Are Wired for Free Will

Dartmouth’s Peter Tse ’84, an associate professor of psychological and brain sciences, says he has identified a neurological basis for free will in the human brain, challenging a majority opinion that has dominated neuroscience for the last 40 years.

Measurements of human brain signals on the level of neurons and synapses have long shown that acts of will are preceded by a buildup of neural activity in the brain. These signals can begin up to seconds before a person is consciously aware of the exercise of volition, according to the weight of data, Tse explains.

Until now, neuroscientists have argued that because this buildup of signals comes before a person acts, or is even conscious of having decided to act, free will cannot exist, because it would require that a thought causes itself to exist before it exists.

“How can something cause its own physical basis? It is this ‘you can’t pick yourself up by your own bootstraps’ idea that has been the main argument against the possibility of free will,” Tse says.

How Music and Movement Communicate Emotion

Joe Blumberg

Music and movement reflect the rhythm of life, stirring human emotions in societies around the world. Even infants display signs of the interconnectedness of music and movement as they bounce up and down to musical rhythms. Music and movement might be characterized as two sides of the same coin—the coin being emotion.

Gaining an understanding of the connections between these behavioral expressions is a quest Dartmouth researchers have undertaken. The research team in Cambodia included (from left) Thalia Wheatley, Stanford graduate student Trent Walker (Khmer translator), Yam Pan (the commune village chief and translator from Khmer to Kreung—the tribal language), and Dartmouth graduate students Beau Sievers and Carolyn Parkinson. (Photo courtesy of Thalia Wheatley)