Once a week.
Subscribe to our weekly newsletter.
How the Brain Fears
The amygdala, an almond-shaped structure in the limbic system, is where the the brain processes and reacts to frightening stimuli. Because of its mechanism, our emotional responses to situations that feel dangerous are often unconscious.
Emotions are messy, complicated phenomena—not just for lovers, but for neuroscientists as well, because they combine cognition with physiology. Scientists once thought of emotion as a purely mental activity which elicited bodily responses, but they now see the mind and body as equally responsible for creating the experiences of fear, joy, and anger. Despite this complexity, science is beginning to understand emotion by examining one emotional pathway at a time, with the hope of some day combining them into a comprehensive understanding.
Fear is the most researched and best understood of all emotions. It's the easiest emotion to study because it has the most measurable physiological response, but it's also the most important emotion we have from an evolutionary standpoint. Learning to fear something dangerous that caused pain in the past, like a snake or a spider, most likely helped our ancestors to survive. And proving its evolutionary importance, the fear circuit in our brains is actually a shortcut that allows dangerous stimuli to bypass parts of the brain normally involved in sensory processing, as NYU neuroscientist Joseph LeDoux explains in the video below.
During normal perception, our sense organs transmit stimuli to part of the brain called the thalamus en route to the sensory cortex, where perceptions and thoughts are generated. To have a visual perception, for instance, "information has to be transmitted from the eye, from the retina, through the optic nerve, into the visual thalamus, and from the visual thalamus to the visual cortex, where the processing continues and you can ultimately have the perception," says LeDoux. "The visual cortex connects directly with the amygdala, and so that one route by which the information can get in: retina, thalamus, cortex, amygdala."
But LeDoux, one of the foremost researchers of emotion and fear in the brain, discovered early in his research that fear, despite being reliant on sensory stimuli to trigger the amygdala, was not processed via the normal sensory pathways, or at least not entirely. "What we found was that if the cortical pathway was blocked completely. Rats could still form a memory about a sound." Instead of traveling from ear to thalamus to cortex to amygdala, the loud sound could bypass the cortex altogether, going directly from thalamus to amygdala. "This was really important because we generally think that the cortex is required for any kind of conscious experience," LeDoux says. In other words, a frightening stimulus can trigger emotions and fears unconsciously—without our even realizing it.
To illustrate this point, LeDoux proposes the following scenario: "Let’s say we were having lunch one day and there’s a red-and-white checkered table cloth, and we have this argument. And the next day I see somebody coming down the street and I say, I have this gut feeling about this guy, he’s an SOB and I don’t like him. And maybe what’s going on there is that he’s got a red-and-white checkered necktie on. Consciously, I’m saying it’s my gut feeling because I don’t like the way he looks, but what’s happened is that the necktie has triggered the activation of the amygdala through the thalamus, the so-called low road, triggered a fear response in me, which I now consciously interpret as this gut feeling about not liking the guy. But in fact, it’s being triggered by external stimuli that I’m not processing consciously."
And this unconscious processing of frightening stimuli happens much more quickly than our conscious processing of it. To become consciously aware of a particular stimulus takes 250-300 milliseconds, says LeDoux. But a fear-evoking stimulus can reach the amygdala in a mere 12 milliseconds, which is evolutionarily advantageous if one's response time means the difference between life and death.
LeDoux's research is important because it helps to explain why people have fears and phobias that they don't consciously understand. "It may be that, through various kinds of experiences, the low road gets potentiated in a way that it's activating fears and phobias outside of conscious awareness and that doesn't make sense in terms of what the conscious brain is looking at...or hearing in the world because they've been separately parsed out."
Getting a better understanding of the the neural pathways associated with fear helps psychologists combat fear and anxiety disorders, something LeDoux continues to research. Currently, he is studying rats that exhibit extreme fear to a stimulus. After conditioning 10 or 20 rats to be afraid of a sound paired with a shock, there will usually be a couple of rats which are more afraid of the stimulus than the others, says LeDoux. Typically, the responses would be averaged together to get the mean, ignoring these outlier rats, which are seen as "nuisances" for adding variance to the data. But LeDoux has chosen to focus entirely on these previous nuisances, hoping to better understand pathological fear. "We can compare animals that are really afraid and those that are not afraid and look in their brains and see if there are any, for example, structural differences in the amygdala," he says. "We can get a lot of information that might distinguish fearful and not so fearful rats that could provide important clues as to what pushes them out there towards the extremes."
LeDoux's research on these scared-y rats is just beginning, but he believes it may yield insights for psychopharmacology. "Almost all of the drugs that are developed to treat fear and anxiety are developed on that average animal, rather than the extremes," he says. "The drugs would be much more effective and perhaps have fewer side effects if they were targeted for the animals with extreme fear."
Fear is the best understood of all emotions, neurologically speaking. And the amygdala, an almond-shaped structure in the limbic system, is considered to be the seat of fear in the brain (as well as other emotions). But fear is processed differently than other emotions, bypassing the sensory cortex on its way to the amygdala. This explains why emotional responses are often unconscious—and why phobias and anxiety may be caused by conditioned responses to stimuli that the sufferer may not consciously fear.
— A primer on the amygdala, by Joseph LeDoux.
— "The Amygdala Modulates Memory Consolidation of Fear-Motivated Inhibitory Avoidance Learning But Not Classical Fear Conditioning," (2000) co-published by Joseph LeDoux in The Journal of Neuroscience.
What is human dignity? Here's a primer, told through 200 years of great essays, lectures, and novels.
- Human dignity means that each of our lives have an unimpeachable value simply because we are human, and therefore we are deserving of a baseline level of respect.
- That baseline requires more than the absence of violence, discrimination, and authoritarianism. It means giving individuals the freedom to pursue their own happiness and purpose.
- We look at incredible writings from the last 200 years that illustrate the push for human dignity in regards to slavery, equality, communism, free speech and education.
The inherent worth of all human beings<p>Human dignity is the inherent worth of each individual human being. Recognizing human dignity means respecting human beings' special value—value that sets us apart from other animals; value that is intrinsic and cannot be lost.</p> <p>Liberalism—the broad political philosophy that organizes society around liberty, justice, and equality—is rooted in the idea of human dignity. Liberalism assumes each of our lives, plans, and preferences have some unimpeachable value, not because of any objective evaluation or contribution to a greater good, but simply because they belong to a human being. We are human, and therefore deserving of a baseline level of respect. </p> <p>Because so many of us take human dignity for granted—just a fact of our humanness—it's usually only when someone's dignity is ignored or violated that we feel compelled to talk about it. </p> <p>But human dignity means more than the absence of violence, discrimination, and authoritarianism. It means giving individuals the freedom to pursue their own happiness and purpose—a freedom that can be hampered by restrictive social institutions or the tyranny of the majority. The liberal ideal of the good society is not just peaceful but also pluralistic: It is a society in which we respect others' right to think and live differently than we do.</p>
From the 19th century to today<p>With <a href="https://books.google.com/ngrams/graph?year_start=1800&year_end=2019&content=human+dignity&corpus=26&smoothing=3&direct_url=t1%3B%2Chuman%20dignity%3B%2Cc0" target="_blank" rel="noopener noreferrer">Google Books Ngram Viewer</a>, we can chart mentions of human dignity from 1800-2019.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg0ODU0My9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY1MTUwMzE4MX0.bu0D_0uQuyNLyJjfRESNhu7twkJ5nxu8pQtfa1w3hZs/img.png?width=980" id="7ef38" class="rm-shortcode" data-rm-shortcode-id="9974c7bef3812fcb36858f325889e3c6" data-rm-shortcode-name="rebelmouse-image" />
American novelist, writer, playwright, poet, essayist and civil rights activist James Baldwin at his home in Saint-Paul-de-Vence, southern France, on November 6, 1979.
Credit: Ralph Gatti/AFP via Getty Images
The future of dignity<p>Around the world, people are still working toward the full and equal recognition of human dignity. Every year, new speeches and writings help us understand what dignity is—not only what it looks like when dignity is violated but also what it looks like when dignity is honored. In his posthumous essay, Congressman Lewis wrote, "When historians pick up their pens to write the story of the 21st century, let them say that it was your generation who laid down the heavy burdens of hate at last and that peace finally triumphed over violence, aggression and war."</p> <p>The more we talk about human dignity, the better we understand it. And the sooner we can make progress toward a shared vision of peace, freedom, and mutual respect for all. </p>
With just a few strategical tweaks, the Nazis could have won one of World War II's most decisive battles.
- The Battle of Britain is widely recognized as one of the most significant battles that occurred during World War II. It marked the first major victory of the Allied forces and shifted the tide of the war.
- Historians, however, have long debated the deciding factor in the British victory and German defeat.
- A new mathematical model took into account numerous alternative tactics that the German's could have made and found that just two tweaks stood between them and victory over Britain.
Two strategic blunders<p>Now, historians and mathematicians from York St. John University have collaborated to produce <a href="http://www-users.york.ac.uk/~nm15/bootstrapBoB%20AAMS.docx" target="_blank">a statistical model (docx download)</a> capable of calculating what the likely outcomes of the Battle of Britain would have been had the circumstances been different. </p><p>Would the German war effort have fared better had they not bombed Britain at all? What if Hitler had begun his bombing campaign earlier, even by just a few weeks? What if they had focused their targets on RAF airfields for the entire course of the battle? Using a statistical technique called weighted bootstrapping, the researchers studied these and other alternatives.</p><p>"The weighted bootstrap technique allowed us to model alternative campaigns in which the Luftwaffe prolongs or contracts the different phases of the battle and varies its targets," said co-author Dr. Jaime Wood in a <a href="https://www.york.ac.uk/news-and-events/news/2020/research/mathematicians-battle-britain-what-if-scenarios/" target="_blank">statement</a>. Based on the different strategic decisions that the German forces could have made, the researchers' model enabled them to predict the likelihood that the events of a given day of fighting would or would not occur.</p><p>"The Luftwaffe would only have been able to make the necessary bases in France available to launch an air attack on Britain in June at the earliest, so our alternative campaign brings forward the air campaign by three weeks," continued Wood. "We tested the impact of this and the other counterfactuals by varying the probabilities with which we choose individual days."</p><p>Ultimately, two strategic tweaks shifted the odds significantly towards the Germans' favor. Had the German forces started their campaign earlier in the year and had they consistently targeted RAF airfields, an Allied victory would have been extremely unlikely.</p><p>Say the odds of a British victory in the real-world Battle of Britain stood at 50-50 (there's no real way of knowing what the actual odds are, so we'll just have to select an arbitrary figure). If this were the case, changing the start date of the campaign and focusing only on airfields would have reduced British chances at victory to just 10 percent. Even if a British victory stood at 98 percent, these changes would have cut them down to just 34 percent.</p>
A tool for understanding history<p>This technique, said co-author Niall Mackay, "demonstrates just how finely-balanced the outcomes of some of the biggest moments of history were. Even when we use the actual days' events of the battle, make a small change of timing or emphasis to the arrangement of those days and things might have turned out very differently."</p><p>The researchers also claimed that their technique could be applied to other uncertain historical events. "Weighted bootstrapping can provide a natural and intuitive tool for historians to investigate unrealized possibilities, informing historical controversies and debates," said Mackay.</p><p>Using this technique, researchers can evaluate other what-ifs and gain insight into how differently influential events could have turned out if only the slightest things had changed. For now, at least, we can all be thankful that Hitler underestimated Britain's grit.</p>
Apple sold its first iPod in 2001, and six years later it introduced the iPhone, which ushered in a new era of personal technology.
A biologist-reporter investigates his fungal namesake.
The unmatched biologist-reporter Tomasz Sitarz interviews his fungal namesake, maślak sitarz – known in English as the Jersey cow mushroom.