The Selfish Brain

by Lindsay Borthwick

What patterns of neuronal activity emerge when a monkey chooses to be generous... or not?

A member of the Kavli Institute for Neuroscience at Yale University, Steve Chang studies the brain mechanisms underlying social behavior, such as what patterns of neuronal activity are present when a monkey chooses to be generous and share food (or decides to be selfish and enjoy it alone like the above macaque in Thailand). ​

The Author

Lindsay Borthwick

The Researchers

Steve Chang
Fred “Rusty” Gage
Mazen Kheirbek
Marina Picciotto
Paul Muller

This month’s highlights from the Kavli Neuroscience Institutes demonstrate the remarkable breadth of research on nervous system, from the role of a protein that surrounds nerve fibers to the brain patterns the give rise to complex social behaviors and decision-making.

To give or not to give

In a new study, Yale neuroscientist Steve Chang and his research team were able to predict a monkey’s decisions during a set of behavioral tasks just by analyzing the animal’s brain activity patterns. The researchers found that the tasks, which forced the monkeys to choose between being generous or selfish, corresponded with distinct patterns of neuronal activity between two brain areas, the amygdala and medial prefrontal cortex. When the primates were behaving generously, by sharing juice with one another, there was greater synchrony between the two areas. “We all know there are individual differences in levels of generosity. Maybe Scrooge did not have high levels of synchrony after all,” Chang told Yale News. He is a member of the Kavli Institute for Neuroscience at Yale University. The experiments are part of Chang’s research on the brain mechanisms underlying social behavior.

Potassium and your mood

Lithium is commonly used to treatment bipolar disorder, but approximately one-third of individuals with the disorder don’t respond to the mood-stabilizing drug. Researchers led by Fred “Rusty” Gage, who is co-director of the joint UCSD/Salk Kavli Institute for Brain and Mind, are beginning to understand why. The culprit may be changes in potassium currents, which are created as potassium travels out of neurons through dedicated channels in the cell membrane and help control the cell’s excitability, or readiness to respond to incoming signals. In a series of studies, the compared human neurons from individuals with bipolar, some of which responded to lithium and some of which did not, and pinpointed potassium currents as the key difference between the two cell types. Understanding this difference could eventually lead to more personalized treatments for bipolar disorder.

Healthy CA3 pyramidal neurons stained to show the cell body (blue) and axons (green).
Healthy CA3 pyramidal neurons stained to show the cell body (blue) and axons (green). Credit: Salk Institute.​

Rethinking myelin

Myelin, the sheath of protein and fat that surrounds nerve fibers, ensures the rapid propagation of signals along nerve fibers. Now, a study from researchers at UCSF suggests myelin is also essential to the formation of emotional memories. Led by Mazen Kheirbek, a member of the Kavli Institute for Fundamental Neuroscience, the research team studied changes in myelination in mice during a learning task—in particular, in response to a fearful experience. They found increased myelin formation in brain regions important for long-term memory—and that new myelin is required for memory consolidation and maintenance. Together with other recent studies showing the formation of myelin during motor learning and spatial learning, the findings are changing the way scientists view the role of myelin-producing cells called oligodendrocytes in the brain. The research also has implications for the treatment of mood and anxiety disorders like PTSD, in which learning-related changes in the brain have negative consequences.

Vaping on the brain

What is the impact of vaping on the developing brain? Neuroscientists like Marina Picciotto, deputy director of the Kavli Institute for Neuroscience at Yale, are beginning to answer that question, the implications of which are critically important for guarding the public health and informing health policy decisions. An article this month in Science magazine summarizes what Picciotto’s research team is learning about the effects of nicotine, which she says is both highly addictive and enhances the rewarding effects of flavors and other stimuli, on the developing brains of mice. The findings are still preliminary, but their studies have shown that adolescent mice exposed to nicotine have structural changes in their brains. The mice are also more sensitive to stress, a behavioral change that has also been documented in children exposed to nicotine before birth.

A rewarding research path

a photo of paul muller
Paul Muller

Paul Muller, a graduate student at Rockefeller University and fellow of the Kavli Neural Systems Institute (where he also serves on the steering committee), has been studying the relationships between neurons in the intestinal tract and intestinal macrophages, a kind of immune cell. His discoveries have uncovered important new ways by which immunity and neurology interact, and have now has earned him a 2020 Harold M. Weintraub Graduate Student Award. Given by the Fred Hutchinson Cancer Research Center, the Weintraub Award is among the world’s most prestigious graduate student prizes in the biosciences.

Written by Lindsay Borthwick

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