The Giving Brain: A Look at the Neurology of Altruism

(Editor’s note: This article is from a past issue of Brain World magazine. If you enjoy this article, please consider a print or digital subscription!)

Back in 1982, the iconic American actor, film director, and entrepreneur Paul Newman founded Newman’s Own, a food company that turned a $300,000 profit margin in its first year. To this success, Paul exclaimed, “Let’s give it all away to those who need it.” Donating all after-tax profits was unique for the time, and Newman became one of the world’s leading philanthropists.

Whether managing a charitable fund, investing funds in a nonprofit, or giving alms to the poor, there seems to be a feeling of happiness in those who give. Today, cognitive and affective neuroscientists are trying to determine whether this extrinsic behavior of giving away has an intrinsic source within the brain’s circuitry. Questions arise as to whether altruism has a clear neurological signature, and if so, by what measurable variations in neural activity and networking differentiates those who give often and those who don’t. To better understand the neurological variations of altruism, one must investigate why altruism is there in the first place.

There are two popular hypotheses used to explain altruism common among organisms neurologically capable of such behavior: reciprocal altruism and kin selection. According to reciprocal altruism, evolution favors organisms who sacrifice for others to receive favors in return. Kin selection suggests that an individual behaves altruistically towards those who share its genes, in a hope that those genes are passed on. Both theories describe an altruism that allows particular organisms to sacrifice their own reproductive fitness. However, in order to explain altruistic behavior which does not typically involve a sacrifice of reproductive fitness in humans, scientists have been studying how the brain is activated by charity-giving.

If money is such a valuable good, economists are confused as to why people voluntarily give it away at such a high rate. Charitable donation behavior uniquely expresses our ability to link motivational significance to abstract moral beliefs and societal causes. In order to observe the particular neural mechanisms by which altruistic behavior is expressed, researchers use functional magnetic resonance imaging (fMRI) data to detect changes in cerebral blood flow within the brain. Such imaging analysis was exercised by Dr. Scott Huettel of Duke University Medical Center in a study published in Nature Neuroscience.

In order to know whether altruistic behavior does in fact have a neurological correlation, and if so, what particular regions are recruited for its execution, Huettel studied a simple precursor to human altruism: Our ability to know the intentions of others. Huettel decided to analyze modulated activity within the posterior superior temporal cortex, a region of the brain that is typically involved with inferring the purposeful acts and intentions of others, during situations that can be defined as being altruistic in nature. If altruism has a neuroscience, then this is where it can be seen.

Subjects were asked to play a computerized reaction game. Depending on how well the computer or the subject performed in the game, money was rewarded directly to either the subject or a charity. After the game, subjects completed a behavioral self-assessment scale designed to measure their everyday altruism. By analyzing their behavioral self-assessment scales and fMRI results, researchers found that subjects who proclaimed themselves to be altruistic by nature displayed higher activity in their posterior superior temporal cortex (pSTC) when observing the computer play the game rather than playing it themselves. The activity within the pSTC of altruistic subjects became even stronger when the reward money was donated to a charity rather than given to them.

Alas, altruism has a home within the brain. But this was not particular enough. By using more accurate imaging analysis, Huettel and his research team found that it was the activation of the right pSTC which directly correlated to altruistic behavior and not other virtuous qualities of emotion such as empathy, personality, or compassion. Furthermore, the specific recruitment of the bilateral orbitofrontal cortex (OFC) was highly activated in conjunction with the pSTC while subjects watched the altruistic deed of another (i.e. the computer donating the reward money to a charity). This activity, whether low or high, was so pronounced that Huettel and his team were actually able to predict how subjects were going to score on the altruism self-assessment; if someone thinks they are more altruistic than they actually are, this now can be seen.

These colorful results drastically differed from the ones taken from the subjects who rated themselves to be behaviorally nonaltruistic. Their pSTC activation did not change much whether they were playing the game, watching the computer play the game, or whether the game’s earnings were being given to them or a charity. It seems that being a nonaltruistic individual is somewhat boring, neurologically speaking. But can we in fact consider these neurologically active and behaviorally assessed charitable individuals truly altruistic?

In order to be considered “purely altruistic,” a person must sacrifice something (time, energy, or possessions) for someone without expectation of any direct or indirect compensation. In other words, are altruistic people giving to others in order to consciously or subconsciously benefit from some degree of self-satisfaction or do they give purely out of selflessness? Is it even possible to give without feeling just a little better about yourself?

Economist William T. Harbaugh and psychologist Ulrich Mayr of the University of Oregon set out to reveal what is really happening within the brains of people who give and whether the neuroarchitecture of giving can be considered a sign of “pure altruism.” In a study published by Science, Harbaugh’s team gave a cash amount of $100 to each participating subject and placed them within an fMRI scanner. A computer screen placed before each of the subjects presented them with opportunities to donate to a food bank. Donations were either made voluntarily or involuntarily (with forced donations between $15 to $45 being made). Participants were instructed that they could keep any money left over at the end of the study session.

When subjects were donating voluntarily or involuntarily the nucleus accumbens, a part of the brain associated with the processing of unexpected rewards, became active. Within this particular region of the brain lie neurons that secrete dopamine, a neurotransmitter that plays a key role in reward-motivated behavior. The team found higher amounts of dopamine within the nucleus accumbens of each subject when voluntarily choosing to donate as opposed to when they were forced to. Among those who donated voluntarily, there were a particular few whose nucleus accumbens showed exceptionally high activity.

(Editor’s note: This article is from a past issue of Brain World magazine. If you enjoy this article, please consider a print or digital subscription!)


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