Introduction to the Neuroscience of Emotion Series

Eliza Bliss-Moreau

In the coming months, we will be posting a number of stories on the neurobiology of emotion. Understanding how the brain creates emotion has important consequences for everything from whom we charge with crimes (are crimes that occur due to a brain disorder that changes emotions different from those that are not?) to how we treat depression (is using chemicals that effect the brain a better option than talk therapy?) to the ethics associated with meat production (if pigs have brains capable of emotions, does that change how we treat them as we turn them into meat?).

As neuroscientists in the 21st century, we are equipped with powerful tools to ask questions about emotion. Modern neuroscience techniques are comparable to the methods detailed in science fiction decades ago—we can “see” into the brain of a normal person while they are in a MRI scanner experiencing emotions; we can turn on and off areas of animal brains with a beam of light; we can record activity of single cells in the brain of animals and nerves throughout the body.  The experiments that use these tools and the data that are produced by these tools are complex and often indirect measures of brain function and the emotion produced by brain activity.  Their portrayal in the modern media often does not do justice to their complexity.

Over a series of posts, we’ll explain how different neuroscience methods actually work, how they are used to study emotion, and what the take home messages are about how the brain creates emotions.  We hope to paint a picture of how exciting and challenging research on the brain basis of emotion is, how powerful our existing tools are, and how much we still have to learn.

Neuroscience stories about emotion make the national and international news frequently these days (like this, this, and this, for example). With the abundance of these stories, it’s easy to forget that it wasn’t that long ago that we had very limited tools to study the brain in a living, breathing person or nonhuman animal. [In later posts, we’ll talk about what we’ve learned about emotion from brains that are not in living beings.] Prior to the advent of neuroimaging technology which lets us measure activity in the brain (either electrical activity, blood flow, or the movement of chemicals), most studies of human emotion occurred when people incurred brain damage.

Perhaps the most famous case of accidental brain damage interfering with emotion, is the case of Phineas Gage. Phineas Gage was a railroad worker born in the 1820s.  In 1848, he was working to build a railroad in Vermont when a terrible accident occurred.   He was using a long metal rod and blasting powder to blast rock away at the site.  During one of the blasts, he lost control of the rod and it flew through his head.   The metal rod entered his skull under his left eye and exited out of the top of his head, damaging a large area of frontal cortex in the process (see).  Surprisingly, Gage lived.  But he was never the same again.  Prior to the accident, he was a responsible, upstanding guy.  After the accident he was said to be vulgar, unable to control his behavior, and generally intolerable.  [Although, there’s a fair amount of debate about the extent to which his behavior actually changed on account of poor records, see].  Modern studies of the brain areas damaged in Gage’s case suggest that those areas contribute to the regulation of emotions.

Gage’s case was just one of many that point to a link between particular areas of the brain and the generation and regulation of emotions.  The next post in this series will address what we’ve learned about emotion from other instances in which humans acquire brain damage.  Sometimes damage is created intentionally—typically to treat intractable diseases (like seizure disorders).  Sometimes damage occurs during strokes.  Finally, there are some diseases out there that target specific brain areas and render them nonfunctional.

In addition to exploring what the emotional lives of people with brain damage have taught us about the neuroscience of emotion, we’ll also be answering questions like: How does neuroimaging really work?  What have animal studies of the brain and emotion taught us? What are the biggest and most dramatic misconceptions about the neuroscience of emotion? How do different brain areas work together to create emotions?

If there are other specific topics you would like to see covered, please email one of the founders or leave a comment for us below.

Empathy is limited, if you want it to be

Daryl Cameron

This year, nearly 60,000 undocumented, unaccompanied children have crossed the southern border into the United States, creating a humanitarian crisis and fueling intense political debate. Should these children be granted moral and legal rights? Should we have empathy for their suffering?

When faced with crises this large, people often think of Mother Teresa’s line: “If I look at the mass, I will never act.” Large numbers of victims seem overwhelming and hard to think about, and are often treated as a cold statistic. This response seems to reveal a capacity limit on empathy: empathy is stronger for a single, identifiable victim (such as Baby Jessica, trapped in the well) than for large groups of victims (such as the thousands of border children). We appear to be numb to numbers. This deficit is striking because many people think that they would feel more empathy as the numbers increase, and that they have an obligation to do so. Empathy seems to fail when it is needed the most.2864579787_902f3bf723_z-2

Recently, many authors—including psychologist Paul Bloom, philosopher Jesse Prinz, and columnist David Brooks—have argued that because empathy is biased toward identifiable victims, it should not be trusted when making moral, legal, and policy decisions. As put by Bloom, “empathy is narrow; it connects us to particular individuals, real or imagined, but is insensitive to numerical differences and statistical data.” As put by Prinz, “we contribute more to a neighbor in need than to the thousands ravaged by a distant tsunami or the millions who die from starvation or disease… in making policy, we would be better off ignoring empathy.”

But what if the limits of empathy aren’t set in stone? A growing number of studies reveal that seemingly fixed limits on empathy may be malleable. Lapses of empathy may reflect motivated choices to avoid empathy. Empathy itself may not be the problem, as its critics suggest; the real problem may be in the choices people make to avoid empathy.

First, it is important to define empathy. When psychologists discuss limits of empathy, they typically mean “emotional empathy”: vicarious sharing of others’ experiences (i.e., “feeling with”—if you’re upset, I get upset). Empathy can lead to many responses, including compassion: an other-focused emotion that motivates pro-social behavior (i.e., “feeling for”—if you’re upset, then I want to relieve your suffering). Critics often focus on limits of empathy, but suggest that compassion is a good thing; however, the bias toward single victims emerges for both empathy and compassion. I have termed this effect “compassion collapse”, but it can occur for both empathy and compassion.

With those definitions in mind, much work reveals that limits in empathy may be motivated, not fixed. My favorite anecdote to explain this idea draws upon the famous commercial by the Society for the Prevention of Cruelty to Animals, starring Sarah McLachlan. The two-minute video (which you can choose to watch here) sets McLachlan’s rendition of “In the Arms of the Angel” to images of abused puppies and kittens. Although I strongly support animal rights, I find it difficult to watch the commercial and sometimes turn it off to avoid being emotionally exhausted by the suffering. It is precisely because I care about their welfare that the emotional cost is so high. Even Sarah McLachlan has said that she changes the channel when her commercial comes on to avoid being overwhelmed by her emotions.

This is an example of motivated emotion regulation: changing the situation to avoid costly empathy. But anecdotes are not data, and many psychology experiments support this idea. Two decades ago, one set of studies showed that people avoid hearing appeals for help that induce high empathy if they anticipate that helping will be costly. More recently, I examined whether motivated emotion regulation could explain compassion collapse. If people predict more emotion as the numbers increase, this may create concerns about financial and emotional costs, leading to empathy avoidance. In one experiment, we had participants read about one or eight child refugees in Darfur. Half of participants expected to donate money and the other half did not. When participants expected to donate, they tended to show more compassion for one victim than eight victims; but when this cost was removed, they felt more compassion for eight victims than one victim. Changing motivation to avoid empathy flipped the compassion collapse.  We also found that compassion collapse only emerged for skilled emotion regulators, suggesting that emotion regulation is necessary for the effect to emerge. Empathy and compassion seem insensitive to large numbers, but this may not be a capacity limit: instead, it may be due to strategic choices to regulate emotions.

In his article, Bloom notes that “experiencing others’ pain leads to exhaustion and burnout.” This emotional cost could motivate empathy regulation, and indeed, doctors appear to regulate empathy to avoid such costs. My lab is currently exploring how exhaustion costs lead us to dehumanize others. As put by Iowa Writers’ Workshop alumna Leslie Jamison in her response to Bloom, “if burnout and exhaustion are the dangers of too much empathy, then abstraction is the danger of too little.”

A motivated perspective on empathy is gaining traction in the field. Narcissists and psychopathic offenders tend to show less empathy for others, but instructing them to empathize reduces these deficits. What people think about empathy also matters: people who believe that empathy can be cultivated—as opposed to being fixed—exert more effort to feel empathy. This work parallels findings on self-control: whereas some claim that self-control is a limited-capacity resource, others reveal that self-control limits only emerge for people who believe that self-control is limited, suggesting that motivation has a role.

In short, let’s not blame empathy for the motivated choices that we make to avoid it. In some situations, empathy may only be as limited as we want it to be.

Fruits, vegetables, and emotions

Tamlin Conner

Should people reach for a carrot rather than a candy bar to help protect against depression? Does a diet rich in fruits and vegetables actually make you happier? These are questions I ponder when not writing guest blogs for my friends.

The answer to these questions seems to be a growing yes.

There is compelling evidence that a healthier diet protects against depression. Multiple studies published in the last decade – mainly in nutrition journals – have found reduced risk for depression among people with a higher intake of fruits and vegetables. This link holds when controlling for socioeconomic status, education, physical activity, smoking, unhealthy food consumption, and pretty much any other variable you can think of that might explain this pattern. And, the evidence suggests that poor dietary intake precedes the onset of depression and not the other way around.

My research adds another flavor to this unfolding story. For the last six years, I have been tracking people’s daily intake of fruit and vegetables to see how consumption is related to changes in daily emotion. In each of these studies, I have found a striking and strong association between daily fruit and vegetable consumption and a variety of positive emotions like happiness. In my first study, I asked 281 young adults ages 18 – 25 to report their mood each day for three weeks, and to report the number of servings eaten that day of fruits and vegetables (canned, frozen or fresh, but not fried and not juices), and several types of unhealthy foods like cookies, potato chips, and desserts. I found that on days when people ate more fruits and vegetables, they reported feeling much happier. Unhealthy foods like chips and desserts had little to no association with mood. Also, by tracking people on a daily basis across those three weeks, I was able to address which came first – eating fruit and vegetables or feeling happy. I found that eating more fruit and vegetables predicted improvements in happiness the next day – but happiness did not predict eating more fruits and vegetables the next day – suggesting that diet preceded changes in happiness and not the other way around.

Recently, I published another study that replicated and extended this finding by showing that fruit and vegetable consumption predicted other positive emotional states even more strongly than happiness—states like how engaged and inspired people felt that day, how interested and curious they were in their environment, and, how creative they felt. In fact, these patterns were almost twice as strong as the patterns found with happiness. What is going on here? There may be a connection between fruit and vegetables and the motivation or drive to engage in daily life – known in scientific parlance as approach motivation.

There are biologically plausible pathways for why fruit and vegetables could promote engagement and drive. Fruit and vegetables contain a range of vitamins and minerals including vitamin C, folate, vitamin B-6, iron, and selenium. Vitamin C might be a key pathway here. It is an important co-factor in the production of dopamine, which is critical to motivational drive. A recent study found increased vitamin C levels in the blood following kiwifruit consumption with corresponding improvements in emotional vitality. B-vitamins and complex carbohydrates in fruit and vegetables also promote the synthesis of dopamine and serotonin.

The absence of approach motivation – called motivational anhedonia – is one of the key features of depression. This raises the possibility that a sustained lowered intake of fruit and vegetables could contribute to motivational anhedonia, which could raise the risk for depression. However, in my research studies of young adults, lower fruit and vegetable consumption related to lower approach motivation but not to higher depression.

What are the next steps? Intervention research. Before getting too excited about these findings, intervention studies are needed to test for causal effects of fruit and vegetables on approach motivational states. This requires getting people to eat more fruits and veggies, testing the consequences for psychological outcomes, and measuring the potential biochemical pathways that could account for such changes.

So, at this stage, I cannot say that eating carrots will make you more creative or that fruit will help you flourish, but the evidentiary base for this is growing. My best advice is to hedge your bet and eat at least five servings per day (two fruit and three or more veggies).  You can do this by including fruit and vegetables at each meal, and the servings will add up across the day.  Bottom line? Opt for carrots rather than candy.