Bartal expected to see this activity in rescue rats, because human empathy emerges in these areas. But she was surprised that even those who it is not rescuing their cages showed neural clues. “The rats are actually dealing with the fact that the rat is in trouble – that he has been captured, that he is unhappy,” she says. “And they activate this system of empathy, whether they help or not.”
If the same machine starts in all cases, but behavior between couples within a group and a group outside a group, what does it give? The difference seems to lie elsewhere, including the nucleus accumbens, which deals with neurotransmitters such as carrots and sticks, such as dopamine, serotonin, and GABA. “It’s active when you eat something tasty, or when you win money or have sex,” says Bartal.
It is often referred to as a brain reward center, she adds, “but today there is more understanding that the picture is not that simple.” A more recent look at the dopamine nucleus accumbens binds him to predict the reward and motivate him to pursue it. “The main function of the brain is to make you approach things that are good for your survival and avoid things that are bad for your survival,” says Bartal.
She repeated her experiment to focus on this area using a method called fiber photometry, which allowed her team to monitor neuronal chatter in live rats. They injected animal accumulators with genetic material that made neurons fluoresce whenever a synapse occurs. They then implanted fiber optic fibers to observe those outbursts of light by watching the rats rush around. And indeed, the rats that released their roommates showed the greatest activity in the nucleus accumbens. The signals of that activity peaked only when they approached to open their snout to their door. That told Bartal that for rats that roam freely, the highlight is the moment of release from restraint, instead of playing with their friend.
Bartal eventually eavesdropped on the rat nucleus with accumbens paint that tracks where the electrical signals come from. She wanted to find out where that motivation for help first came from. (If a a hungry rat is looking for pizza in the New York subway, their gustatory cortex would cause packing.) Taking pieces of the animals ’brains shortly after they performed the rescue mission and observing which areas the color that overlapped with the pockets expressing c-Fos had reached, she could tell which parts of the brain talked to each other.
Bartal followed calls to the motivation center during rodent rescue missions and found a caller she recognized: the anterior articular cortex. He suspects that this points to a line of communication between empathy and reward that could be important for understanding compassionate behavior. But it’s too early “to fully delineate the entire micro-circuit involved,” she says. “We’re working on that now.”
“This is a fantastic study,” Stanford University neurobiologist Robert Sapolsky wrote in a message to WIRED. Sapolsky, who was not involved in the study, wrote the book Behave: Human Biology at its best and worst, which describes what motivates human behavior — namely, the ubiquitous categorization of “us” versus “them”.
The team’s results tell us a lot about ourselves, according to Sapolsky, because experts would predict identical results in the human brain: the difference between us / them, the front cingulate that sets demands, and the batteries that drive motivation. Performing such detailed brain experiments would be unsustainable in humans, and he shows that this shows that what happens in rats offers a bitter-sweet message. The good news, Sapolsky writes, is that “the roots of our ability to help, to empathize, are not the product of Sunday morning sermons. It is older than our humanity, older than our primate; his legacy long precedes us as a species. “The bad news is that our penchant for them — if they are around us — is also ancient.