Neuroscientists Mine the Depths of Emotions
With a new respect for the science of emotion, researchers are charting the anatomy of social graces, capturing neural impulses of fairness and shame that guide behavior.
In findings made public this week at a meeting of 24,000 neuroscientists in Orlando, researchers documented how the primal mood circuits of the brain can color manners, cooperation and judgment, even as scientists revealed a new understanding of how the human capacity for emotion changes over a lifetime.
By focusing on the neural networks that drive feelings, scientists have embraced an objective inquiry into the subjective, emotional life of the mind. Until recently, scientists could make only educated guesses about the nature of the emotional chords struck by joy or sadness.
New noninvasive medical imaging techniques, however, allow scientists to plumb the wellsprings of the mind more precisely. Recording the interplay of neural patterns, they seek explanations for the subtle mood changes that influence our decisions and shape the way we treat each other.
“There has been a shift to looking for brain patterns,” University of Iowa psychologist Daniel Tranel said. “Emotion is a topic that has been deliberately eschewed by neuroscientists for a long time. It was a nuisance in our data and we tried to get rid of it. Now, we deliberately focus on it.”
In their exploration of emotion, researchers at the annual meeting of the Society for Neuroscience this week found:
* Neural circuits related to shame that help regulate social behavior. Researchers at UC Berkeley reported that people with brain damage in a region just above the eyes, called the orbifrontal cortex, could not process the social cues that help fine-tune manners. They persistently acted in an overly familiar manner, telling inappropriate jokes or using off-color language.
* An upbeat side and a downbeat side of the brain. Positive attitudes lodge in the left side of the prefrontal cortex, which is involved in complex reasoning and social awareness, and negative attitudes congregate on the right, according to researchers at the National Institute of Neurological Disorders and Strokes who used functional magnetic resonance imaging (fMRI) to measure brain activity.
* Brain circuits attuned to unfairness. Researchers at Princeton University identified a neural network that responds to an unfair financial offer. They monitored brain activity in volunteers playing the ultimatum game, commonly used to study economic and social decision making. Heightened activity in these areas of the cortex may underlie feelings of indignation.
* Synapses crafted for cooperation. People who exchanged favors displayed heightened neural activity in areas involved in processing rewards and detecting the intentions of others, researchers at Emory University in Atlanta found. That surge of good feeling may explain why people work with others even when it may be against their short-term interest, the researchers suggested.
All in all, it does not take much for an emotional impulse to affect the way we think.
In a study of how even relatively mild emotions influence mental abilities, cognitive neuroscientists at Washington University in St. Louis found that brain areas critical for reasoning, intelligence and other types of higher cognition were swayed by watching a horror film or a TV comedy for as little as 10 minutes.
Published this year in the Proceedings of the National Academy of Sciences, the brain-scanning experiment showed that the videos affected a region of the prefrontal cortex just under the temples, thought to be important for blending cognitive tasks together with emotional signals.
After viewing the clips, people took simple tests of memory and mental ability. Their performance was helped or hindered depending on how their mood had been affected by the videos.
“Mild anxiety actually improved performance on some kinds of difficult tasks, but hurt performance on others,” said psychologist Jeremy Gray, who led the research team.
It doesn’t take a scientist to know that feelings can run ahead of common sense, but now researchers are learning how emotions can trigger errors in judgment.
Researchers at Bay Crest Center for Geriatric Care in Ontario, Canada, measured brain activity in people looking at photos and documented how their emotion circuits responded to a face faster than their memories about it could be retrieved.
That helps explain the awkward situation in which people mistakenly hail as a friend someone they have never met.
Despite individual differences in the depth and intensity of emotional responses, researchers are discovering the same emotional machinery in the very young and the very old, according to new research by independent groups at the University of Montreal in Canada and the University of South Carolina.
“The emotions are hard-wired in the brain and are present very early,” said Montreal researcher Johannes Levesque, who studied how the brains of females processed feelings.
The brain’s emotional circuitry, however, also appears to evolve throughout life, research presented this week suggests.
When 8- and 9-year-old girls were asked to watch sad film clips and then suppress the sadness they evoked, 11 regions of their brains showed increased neural activity, compared with only two regions in adults, the Montreal researchers said.
Older people may appear to be less emotional than the young, but they may feel things more intensely, researchers said this week.
Even as physical measures of emotion, such as heart rate, decline with age -- tempered perhaps by time and experience -- older people still have a depth of feeling that had not been properly appreciated.
“The brain mechanisms tend to be the same across a lifetime,” said psychologist Donald Powell at the Veterans Administration Hospital in Columbia, S.C. “The elderly may feel greater emotions but show it less.”
