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.

According to Mormon author and fruit grower "Dr" Robert O. Young, pretty much all diseases are caused by our bodies being too acidic. By adopting an "alkaline lifestyle" to raise your internal pH (lower pH being more acidic), you'll find that

if you maintain the saliva and the urine pH, ideally at 7.2 or above, you will never get sick. That’s right you will NEVER get sick!

Thus, we speculate that when fear-evoking stimuli activate the amygdala, its pH may fall. For example, synaptic vesicles release protons, and intense neural activity is known to lower pH.

We propose that the shared characteristics of CO2/H+ sensing neurons overlap to a point where threatening disturbances in brain pH homeostasis, such as those produced by CO2 inhalations, elicit a primal emotion that can range from breathlessness to panic.

Continuing the theme of interesting single case reports, I was pleased to see a paper about brain activity in someone who suffered a panic attack in the middle of an fMRI brain scan experiment.

The unfortunate volunteer, a 46 year old woman, was taking part in an experiment looking at restless-leg syndrome. The scan lasted 40 minutes, and everything was going smoothly until quite near the end, when out of the blue, she had a panic attack.

Obviously, the scan had to be abandoned - as soon as the volunteer pressed the emergency "panic button", they stopped the scan and got her out of the MRI. (This kind of thing is why we have such buttons!) However, they decided to see what happened in the woman's brain as the panic started using the data they acquired up to that point.

Here's what they found: the top graph here shows her heart rate. It starts increasing a bit and then spikes, which shows exactly when the attack occurred. What about the brain? Well, amygdala and left insula activity sort of increase around this time. A bit. If you stare at the lines hard enough.

If you believe they did, it makes sense because the amygdala is known to be involved in anxiety (amongst other things) while the insula is responsible for the perception of the body's internal state, which is rather out of whack during a panic attack.

What doesn't make sense is the middle temporal gyrus bit, which was statistically the only part of the brain where activity was significantly correlated with heart rate (in whole-brain analysis). That region is not believed to have anything to do with panic, and to be honest, it's probably just a fluke.

This is only the second published report about panic during fMRI. There was one previous paper from 2006 about an attack in someone with a history of panic, which also found amygdala activation. But there are sure to be others out there which haven't made it into print - anxiety and panic during scans is not unheard of (the scanner is rather claustrophobic). It would be interesting to get more data on this, because it's obviously rather hard to research real-life panic attacks, on account of them being unpredictable.

Spiegelhalder, K., Hornyak, M., Kyle, S., Paul, D., Blechert, J., Seifritz, E., Hennig, J., Tebartz van Elst, L., Riemann, D., & Feige, B. (2009). Cerebral correlates of heart rate variations during a spontaneous panic attack in the fMRI scanner Neurocase, 1-8 DOI: 10.1080/13554790903066909

According to a new paper in the prestigous journal PNAS, High-field MRI reveals an acute impact on brain function in survivors of the magnitude 8.0 earthquake in China.

The earthquake, you'll remember, happened on 12th May last year in central China. Over 60,000 people died. The authors of this paper took 44 earthquake survivors, and 32 control volunteers who had not experienced the disaster.

The volunteers underwent a "resting state" fMRI scan; survivors were scanned between 13 and 25 days after the earthquake. Resting state fMRI is simply a scan conducted while lying in the scanner, not doing anything in particular. Previous work has shown that fMRI can be used to measure resting state neural activity in the form of low-frequency oscillations.

The authors found differences in the resting state low-frequency activity (ALFF) between the trauma survivors and the controls. In survivors, resting state activity was increased in several areas:

"The whole-brain analysis indicated that, vs. controls, survivors showed significantly increased ALFF in the left prefrontal cortex and the left precentral gyrus, extending medially to the left presupplementary motor area... [and] region of interest (ROI) analyses revealed significantly increased ALFF in bilateral insula and caudate and the left putamen in the survivor group..."