Neurology Center

Remember the 90s, when No Fear stuff was cool, and when people still said "cool"?

Well, a new paper has brought No Fear back, by reporting on a woman who has no fear - due to brain damage. The article, The Human Amygdala and the Induction and Experience of Fear, is brought to you by a list of neuroscientists including big names such as Antonio Damasio (of Phineas Gage fame).

The basic story is nice and simple. There's a woman, SM, who lacks a part of the brain called the amygdala. They found that she can't feel fear. Therefore, it's reasonable to assume that the amygdala's required for fear. But there's a bit more to it than that...

The amygdala is a small nugget of the brain nestled in the medial temporal lobe. The name comes from the Greek for "almond" because apparently it looks like one, though I can't say I've noticed the resemblance myself.

What does it do? Good question. There are two main schools of thought. Some think that the amygdala is responsible for the emotion of fear, while others argue that its role is much broader and that it's responsible for measuring the "salience" or importance of stimuli, which covers fear but also much else.

That's where this new paper comes in, with the patient SM. She's not a new patient: she's been studied for years, and many papers have been published about her. I wonder if her acronym doesn't stand for "Scientific Motherlode"?

She's one of the very few living cases of Urbach-Wiethe disease, an extremely rare genetic disorder which causes selective degeneration of the amygdala as well as other symptoms such as skin problems.

Previous studies on SM mostly focussed on specific aspects of her neurological function e.g. memory, perception and so on. However there have been a few studies of her "everyday" experiences and personality. Thus we learned that:

Two experienced clinical psychologists conducted "blind" interviews of SM (the psychologists were not provided any background information)... Both reached the conclusion that SM expressed a normal range of affect and emotion... However, they both noted that SM was remarkably dispassionate when relating highly emotional and traumatic life experiences... To the psychologists, SM came across as a "survivor", as being "resilient" and even "heroic".

A man, whom SM described as looking “drugged-out.” As she walked past the park, the man called out and motioned for her to come over. SM made her way to the park bench. As she got within arm’s reach of the man, he suddenly stood up, pulled her down to the bench by her shirt, stuck a knife to her throat, and exclaimed, “I’m going to cut you, bitch!”

SM claims that she remained calm, did not panic, and did not feel afraid. In the distance she could hear the church choir singing. She looked at the man and confidently replied, “If you’re going to kill me, you’re gonna have to go through my God’s angels first.” The man suddenly let her go. SM reports “walking” back to her home. On the following day, she walked past the same park again. There were no signs of avoidance behavior and no feelings of fear.

You're watching a horror movie.

The characters are going about their lives, blissfully unaware that something horrifying is about to happen. You the viewer know that things are going to end badly, though, because you know it's a horror movie.

Someone opens a closet - a bloody corpse could fall out! Or they're drinking a glass of water - which could be infected with a virus! Or they're talking to some guy - who's probably a serial killer! And so on.

The effect of this - and a good director can get a lot of mileage from it - is that scenes which would otherwise be entirely mundane, are experienced as scary, purely because you know that something scary is going to happen, so you see potential horror in every innocent little thing. An expectation as to what's going to happen, leads to you interpreting events in a certain way, and this creates certain emotions.

In a medical context, that would be called a placebo effect. Or a nocebo effect when expectations make people feel worse rather than better.

The horror movie analogy is useful, because it shows that placebo effects don't just happen to other people. We all like to think that if we were given a placebo treatment, we wouldn't be fooled. Unlike all those silly, suggestible, placebo responders, we'd stay as sick as ever until we got a proper cure.

I wouldn't be so sure. We're always interpreting the world around us, and interpreting our own thoughts and feelings, on the basis of our expectations and beliefs about what's going on. We don't suddenly stop doing this when it comes to health.

Suppose you have the flu. You feel terrible, and you're out of aspirin. You don't think you'll be able to make that meeting this afternoon, so you phone in sick.

Now, clearly, flu is a real disease, and it really does make you feel ill. But how do you know that you wouldn't be able to handle the meeting? Unless you have an extensive history of getting the flu in all its various forms, this is an interpretation, a best guess as to what you'll feel in the future, and it might be too pessimistic.

Maybe, if you tried, you'd get on OK. Maybe if you had some aspirin that would reassure you enough to give it a go. And just maybe it would still have worked even if those "aspirins" were just sugar pills...

Link: See my previous posts I Feel X, Therefore Y and How Blind is Double Blind?

I just watched The Crazies, a remake of Romero's 1973 original of the same name, about a small town struck by an outbreak of insanity following a biological weapon accident. It's not for the faint of heart: I was unsettled by a number of the scenes and I watch a lot of horror movies.

Which is to say, it's excellent. It maintains a high pitch of tension through the whole 100 minutes, something that a lot of horror doesn't manage. All too often, I find, a movie will start out scary enough, but then by some point about half way through it's effectively turned into an action movie.

This happens when the nature of the monster/killer/zombies have been revealed and all the protagonists have to do is fight it out - with the uncertainty gone, the horror goes, too. Without giving too much away, The Crazies avoids this trap. (The last great horror movie I saw, Paranormal Activity, does too, although in a very different way).

Of course the real reason I liked this movie is that it's got some neuroscience. The Crazies is (spoilers) about an engineered virus that infects the brain. Early symptoms include fever, blank stares, flattened emotions and stereotypies. This then progresses, over the course of about 48 hours, to psychopathic aggression, at least in some cases, although other victims just become confused. The "crazies" are somewhat like zombies - they have a Zombie Spectrum Disorder, one might say - but they retain enough of their personality and intelligence to be capable of much more elaborate and calculating violence than the average braaaaaaains-muncher, which is what makes them so disturbing.

Could a virus do that? Rabies, notoriously, causes aggression in animals and humans, although the incubation period is weeks rather than days, and aggression is only one of many neurological symptoms of the disease. But maybe an engineered virus could achieve a more specific effect if it was able to selectively infect the area of the brain reported on in this rather scary paper:

The authors report a patient with advanced PD, successfully treated by bilateral stimulation of the subthalamic nucleus, who developed acute transient aggressive behavior during intraoperative electrical test stimulation. The electrode responsible for this abnormal behavior was located within the lateral part of the posteromedial hypothalamic region (triangle of Sano). The authors suggest that affect can be dramatically modulated by the selective manipulation of deep brain structures.