Reporters have gotten very, very good at writing catchy headlines. With all of the clickbait floating around the internet, the news has become an arms race, and science news is no exception. Since people like hearing about how their brains work, and everyone secretly (not so secretly?) likes reading about sex, drugs and rock and roll, there is often a lot of news coverage when brains and hedonistic pleasures meet.
But where does science end and sensationalism begin? Even as someone well-versed in neuroscience, it can be hard to tell. Today we’ll take a moment to walk you through some of the neuroscience you’re likely to encounter in popular media, and how to tell science from the hype.
And, since it’s Valentine’s day, we thought we’d use articles about the neuroscience of love (and sex and drugs) as our running examples. They range from romantic or instructional to fear-mongering and sensationalistic.
Let’s start with a little background about how we study the brain.
How do we study the healthy human brain?
Many articles about the human brain will include results from neuroimaging studies. This is because neuroimaging is a relatively easy way to measure people’s brains in a painless and noninvasive way. The most popular technique right now is fMRI.
Functional Magnetic Resonance Imaging (fMRI) is essentially a special MRI scan. If you’ve had an MRI scan, you know that an MRI machine is like a giant magnetic doughnut, and we slide the body part we’re interested in scanning into the center of that magnetic donut. An MRI allows doctors to see the structure of your body, beneath your skin.
fMRI is a special way of using an MRI machine that allows us to see not only the shape of your brain, but also the amount of oxygen in the blood in your brain. Your brain cells (neurons) use more oxygen when they are more active, so by measuring the changes in blood oxygen in the brain we can measure the amount of neural activity in a particular region of the brain.
However, because the movement of oxygen in the blood is a slow process, it’s hard to pinpoint exactly when the neuronal activity starts and stops. But we can narrow it down to a few seconds, which is good enough for many purposes. On the other hand, fMRI gives us excellent spatial sensitivity: we can see quite accurately (down to 1 mm3, about the size of a pinhead) which groups of neurons in your brain are more active. fMRI images are 3D pictures of the brain, and are often viewed as many slices.
Below is an example fMRI image. The colors represent more or less active regions (red and blue respectively) relative to the baseline of doing nothing. In this example the left column shows the brain’s response to faces, the right column is the brain’s response to houses.
Image by National Institute of Mental Health – US Department of Health and Human Services: National Institute of Mental Health, Public Domain, https://commons.wikimedia.org/w/index.php?curid=17982524
When using fMRI, researchers are looking for correlations between what they measure in the brain image, and the the task performed (e.g. making a decision, viewing pictures). The increase or decrease in brain activity in response to the task is how neuroscientists say a brain area is involved in a particular cognitive process, and that’s where science reporters get fodder for headlines like “Music is like sex for your brain”.
How do we study the damaged human brain?
Brain imaging only allows us to measure correlations between brain activity and the stimuli that elicit that activity. As you’ve probably heard before, correlation is not causation. That means there’s only so much we can say by measuring changes in activity that seem to happen at the same time as changes in stimuli. The only way to tell for certain if a brain area performs a particular cognitive function is to show that that function is impacted if that brain area is injured. This is often done by studying the brains of those who have had brain injuries, such as strokes. These injuries lead to the death of the neurons in large areas of the brain, called lesions.
The thing about studying humans is that there are (thankfully) very strict rules and regulations about what you can and cannot do to a person’s brain. You most certainly cannot injure a person’s brain just to confirm it is actually required for a particular function*. Instead, we invite stroke/trauma patients to participate in research studies. Then, we can measure that person’s cognitive abilities (and even take fMRI images) to determine what changes their particular brain damage brought about.
Because we have no control over which areas of the brain are lesioned, it is rare that a single brain area, and only that area, is affected by a lesion. That makes it hard to perform lesion studies, and often we still end up making our best guesses about what damage to a particular area of the brain entails.
Wait… what actually causes a neuron to be active?
Many articles talk about brain imaging, but many also talk about neurotransmitters (e.g. dopamine). What are neurotransmitters, exactly, and how do we measure them?
Neurotransmitters are chemicals that allow your neurons to communicate with each other. Each neuron releases neurotransmitters when it is active. Neurons also “receive” neurotransmitters. There are specialized components on each neuron that bind or latch on to particular neurotransmitters. When a neurotransmitter is bound, it causes chemical changes in that neuron that either lead to it being more or less active in the future.
The easiest way to study neurotransmitters is with animals (typically mice). This is because you can invasively assess how much of a given neurotransmitter is present in a particular part of the brain. We can’t exactly peek into human brains, so animal models have been essential for understanding the role of different neurotransmitters.
However, there are ways to study neurotransmitters in humans and how they relate to conscious experience. This technique is used in both the salon and the independent piece. Thanks in part to the aforementioned animal studies, we have developed drugs that can block or enhance the presence of particular neurotransmitters.
Some of these drugs, like L-dopa, have been essential in treating conditions like Parkinson’s disease. Others are more…recreational, such as cocaine.
In any case, if you are interested in how neurotransmitters affect conscious experience, you have to use humans. The experiment is simple: compare the response to a stimulus (such as music) with and without the neurotransmitter.
So you’ve found a cool article, what do you do?
For a non-scientist, science news can be daunting. For a scientist, it can be…depressing. How can we share and understand results without everyone needing a neurobiology degree?
The important thing to remember is that when you read about science in a place like HuffPo, it’s the end result of a game of telephone. Here’s what happened:
- A group of scientists published their work in a research journal
- That research journal or perhaps the scientists’ institution made a press release about the paper, summarizing it in hopefully understandable terms.
- A major news outlet picked up that summary, and tried to make it “edgy” and “interesting.”
The good news is that step 2 is usually freely available, and, if you’re lucky, linked to by the articles in step 3. If you’re interested in getting a less biased but still understandable view of the result, this is the best place to look.
If you can’t find a scientific source for the article/the article doesn’t cite any, it’s a sign that what you’re reading is probably bunk.
Even the plain language summary of the article may include some jargon. Rather than go with the news media’s explanation of what those words mean, we suggest looking them up yourself.
For example, the articles we’ve linked to all talk about dopamine and its role in addiction. This paints a biased view of dopamine and its role in the brain. In reality, neurotransmitters fulfill different functions in different brain areas and are not completely understood. If you were to look up dopamine, you’d see that it is necessary for movement generation. If your body fails to produce enough dopamine, you will develop Parkinson’s disease. In fact, L-dopa, the drug given in this article to show how dopamine influences decision-making, is actually used as treatment for Parkinson’s.
Whether someone suffers from a stroke or has taken a neurotransmitter enhancer/blocker, the effects are never clean. The brain is a heavily interconnected system, and damaging it can cause a wide range of unpredictable changes. Therefore, take these results with a pinch of salt.
Another example is: what does it mean for a brain region to be more active in one situation than in another? As we discussed, with fMRI we can measure how “active” a region is. Many articles, especially this one, draw conclusions from the fact that two different activities (music and sex) cause a particular region to be more active. This result is interesting, but it is a slightly misleading oversimplification. Regions of the brain never act in isolation. It’s possible that there was only one point of similarity between your brain on music and your brain on sex or drugs. Popular media can hype this up and greatly oversell the results.
Lastly, remember the incentives at play. Scientific articles are attempting to provide evidence for a theory that may be true. News article about those scientific articles may be trying to persuade you of myriad other things. Keep that in the back of your mind so that you can read with a grain of salt. That’s a good idea no matter what kind of news you’re reading, on the off chance you fall victim to the newest clickbait headlines.
*The exception here is Transcranial Magnetic Stimulation, which we might cover another day.