The Neuroscience Behind Gratitude

By Mariam Melkumyan

With Thanksgiving a few days away, it seems very hard to find things to be grateful about this year. 2020 gave us COVID-19, environmental issues, political and human rights movements, terrorist attacks and hostility all over the world, including a war in my home country Armenia, and a crazy, stressful period of elections. Yet we, as humans, are programmed to find positivity among all the negativity around us. I find this positivity in the countless memes, TikToks, cute animal videos, my cat, and social interactions with my family and friends on Zoom. But what is the programming in our brain that allows us to be positive, and why is it important to think about what we are grateful for?

Before I get into the neuroscience, it is important to understand the definition of gratitude used when we study it in a lab setting. There are many different definitions of gratitude, with philosophers and psychologists debating the true meaning of gratitude for centuries1. According to Gulliford et al.2, gratitude is more than appreciation or gladness, it involves acknowledging benefit and having a sense of thankfulness towards the benefactor that gave the benefit or gift. Gratitude is described as a deeply social emotion, and the defining factor of gratitude is that a grateful person recognizes that they did nothing to deserve the gift or benefit2. The origin of the word gratitude is grati or gratis, meaning something given for free or in an undeserved way, explaining the notion that we are grateful for things we think we don’t deserve2. You might think this definition seems a little harsh, however, among many philosophers the notion of being undeserving crosses the fine line from appreciation and into true gratitude.

Experiencing true gratitude reminds me of the dopaminergic reward circuitry and the idea of reward prediction error (RPE). In the simplest terms, dopamine is our “reward” neurotransmitter, and it is highly expressed in our limbic cortex, which includes the nucleus accumbens, a region of the brain heavily implicated in addiction. Since dopamine is often highly expressed during a rewarding experience, an increase in reward perception can be assumed when there is an increase in dopamine levels. However, a reward does not always lead to dopaminergic transmission. RPE is the idea that when we predict a certain reward, we may have differential dopaminergic response based on the actual outcome3.

Figure 1: Reward prediction error responses at the time of reward and reward predicting stimuli by peri-event time histogram and raster plot of impulses. The dots (raster plot) signify dopaminergic neuronal impulses, with each horizontal line of dots showing activity from one trial (2-5 neurons per trial). The histogram shows sum of the neuronal impulses from each specific time interval. Left graph shows changes in dopamine neuron output when there was no prediction for the reward, but the reward was received (+Error). Middle graph shows changes in dopamine neuron output when there was a prediction for the reward and the reward was received (0 Error). Left graph shows changes in dopamine neuron output when there was a prediction for the reward, but the reward was not received (-Error). Modified from Schultz, 2016.

More specifically as shown in Figure 1, if we predict a specific reward and get what we expected, the dopaminergic response to the reward disappears3. When this reward is less than expected, the dopaminergic response decreases significantly. In fact, the expectation of a reward elicits a higher dopamine activity than the actual reward3. However, when the actual reward is more than the expected, there is a significant increase in dopamine neuron activity, leading to a stronger response3. Therefore, it is not surprising that the true feeling of gratitude happens when we least expect it, as that is when a benefit is most rewarding. However, it would be too simple if this complex concept of gratitude just depended on one dopaminergic pathway.

Since gratitude animals cannot verbally express when they feel grateful, researchers must study gratitude in humans with imaging techniques, such as functional magnetic resonance imaging (fMRI). A study by Fox et al.4 used fMRI to measure whether gratitude correlates with activity in brain regions that are associated with moral cognition, value judgment, and theory of mind (the understanding that others have thoughts and a general mental state different from our own) (figure 2). These social measures are used because gratitude is a social emotion used to communicate with others, enhance our social relationships, reinforce beneficial behavior, and motivate prosocial behavior in the future5. Fox and colleagues asked participants to view videos of the Holocaust, including stories on how the Red Cross helped during the liberation. The participants were then asked to reflect on how they would feel if they were in the described situation, and how they would rate their gratitude. The researchers saw that the self-reported ratings of gratitude correlated with activity in the anterior cingulate cortex, and the dorsal and ventral regions of the medial prefrontal cortex (MPFC) (figure 2). These regions are implicated in moral cognition, theory of mind, and reward, suggesting that gratitude is not just rewarding, but it involves a social component as well4.

Figure 2: Brain activity during gratitude reflection period compared to baseline. Left and right hemispheres (top), and left and right midsection (bottom) of brain. Grey shows no change from baseline, yellow shows increased activation during reflection, and blue shows decreased activation during reflection. From Fox et al 2015.

So, how is gratitude beneficial for us and society? McCullough and colleague’s classic paper titled “Is Gratitude a Moral Affect” notes three functions that encompass the moral value of gratitude: moral barometer, moral motivator, and moral reinforcer6. The moral barometer is a change in the emotional state that is due to receiving a benefit from another. Gratitude is a moral motivator because it urges us to contribute to the well-being of others, including the benefactor. Gratitude is a moral reinforcer because when we are grateful it makes our benefactors more likely to repeat their beneficial act2,6. Therefore, gratitude perpetuates a cycle of good acting and altruism2. Indeed, an fMRI study showed that grateful people are more likely to have neural signatures of altruism in their reward system regions7.

You should practice gratitude not just on Thanksgiving, but every day of your life. When people kept a gratitude journal, where they wrote down one thing a day for which they were grateful, scientists observed increased activity of brain regions involved in moral cognition, theory of mind and reward, and more altruistic behaviors after only three weeks7. There is a lot of negativity in the world and taking time to think of things we are grateful for can be a very rewarding experience and benefit your mental wellbeing.

Happy Thanksgiving and stay positive!

1.         Emmons RA. The Psychology of Gratitude: An Introduction. Oxford University Press; 2004. Accessed November 10, 2020.

2.         Gulliford L, Morgan B, Kristjánsson K. Recent Work on the Concept of Gratitude in Philosophy and Psychology. J Value Inquiry. 2013;47(3):285-317. doi:10.1007/s10790-013-9387-8

3.         Schultz W. Dopamine reward prediction error coding. Dialogues Clin Neurosci. 2016;18(1):23-32.

4.         Fox GR, Kaplan J, Damasio H, Damasio A. Neural correlates of gratitude. Front Psychol. 2015;6. doi:10.3389/fpsyg.2015.01491

5.         McCullough ME, Kimeldorf MB, Cohen AD. An Adaptation for Altruism: The Social Causes, Social Effects, and Social Evolution of Gratitude. Current Directions in Psychological Science. Published online August 1, 2008. Accessed November 10, 2020.

6.         McCullough ME, Kilpatrick SD, Emmons RA, Larson DB. Is gratitude a moral affect? Psychological Bulletin. 2001;127(2):249-266. doi:10.1037/0033-2909.127.2.249

7.         Karns CM, Moore WE, Mayr U. The Cultivation of Pure Altruism via Gratitude: A Functional MRI Study of Change with Gratitude Practice. Front Hum Neurosci. 2017;11. doi:10.3389/fnhum.2017.00599

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