One of the biggest myths in neuroscience is that a singular brain region—such as the amygdala or insula—is responsible for a specific aspect of social cognition. This week, a team of Stanford and Duke University neuroscientists reported that the frequency-specific interplay between and within various brain regions appears to drive the decision-making process behind altruism and empathy. This study helps to debunk the myth that any singular brain region functions in isolation or with autonomy.
These findings were published online June 19 in the journal Brain and Behavior. Although this was an animal study, the researchers believe this empirical evidence may have applications related to various neural mechanisms that encourage altruistic and prosocial behaviors in humans.
For this study, the researchers monitored the neural activity of oscillating brain waves within and between five different brain regions as rats engaged in the decision-making process of whether or not to help a cagemate in distress. The "Intersubjective Avoidance Test” (IAT) the researchers used is designed to gauge a rat's willingness to enter an innately aversive chamber to prevent another rat from getting a mild electric shock.
Rats who voluntarily entered the innately aversive chamber, and came to the rescue of another rat who was getting shocked, displayed specific activity in brain regions known to be involved in human empathy. This includes the anterior cingulate, insula, orbital frontal cortex, and amygdala. Interestingly, the varying degrees of “intersubjective avoidance” that each rat displayed could be correlated to specific brain wave oscillations between and within these various brain regions.
For example, the researchers found that alpha and low gamma coherence between spatially distributed brain regions predicted more intersubjective avoidance. On the flip side, theta and high gamma coherence between a separate subset of brain regions predicted less intersubjective avoidance. A detailed analysis of these different brain wave frequencies indicated that choice-relevant coherence in the alpha range reflected information passing from the amygdala to cortical structures. Conversely, frequency-specific oscillations in the theta range reflected information passing in the opposite direction.
The new study on the empathetic decision-making process in rats suggests that the exact role of each brain area is never fixed. Rather, the function of each brain region appears to fluctuate depending on the frequency-specific oscillation of messages being sent and received in coordination with other brain regions based on the "neural context" of making decisions that affect others.
Jana Schaich Borg, assistant research professor in the Social Science Research Institute and the Center for Cognitive Neuroscience at Duke was the lead author of this study. She began this research as a graduate student at Stanford University.
In a statement, Schaich Borg summed up her team's findings on elicit empathetic decision-making in rats, "The brain regions that encoded what the rat was choosing to do were the same ones we found in other studies to be involved in human empathy and moral decision making. It's fascinating that rats are using the same brain regions that we seem to be using, and it suggests that rats provide a promising avenue for better understanding the way the human brain makes decisions to help others."
These findings add valuable insights to the ongoing debate on the role that each specific brain region—such as the insula—may play in guiding psychopathic or antisocial behavior, as well as prosocial behaviors. Schaich Borg hypothesizes that the insula may facilitate certain social behaviors when it is communicating with brain regions in one way, but might actually inhibit the exact same behaviors when it is communicating with the same brain region in a different way.
The latest research by the team of neuroscientists at Duke and Stanford University reaffirms the importance of looking at how various brain regions operate in concert with one another. In conclusion, Jana Schaich Borg drives home the importance of studying how brain regions fine-tune communication with one another stating, "To understand how the brain coordinates complex behaviors—especially social behaviors—we likely have to look at the changing inputs and outputs of individual regions in different situations."
"Rat intersubjective decisions are encoded by frequency-specific oscillatory context," Jana Schaich Borg, Sanvesh Srivastava, Lizhen Lin, Joseph Heffner, David Dunson, Kafui Dzirasa and Luis de Lecea. Brain and Behavior, June 2017. DOI: 10.1002/brb3.710