Train of Thought Derailed: How an Accident Can Affect Your Memory

[Buster's Uncle]

Train of Thought Derailed: How an Accident Can Affect Your Brain
Scientific American
Lucas Laursen 16 hours ago
 

My cousin Guillermo Cassinello Toscano was on the train that derailed in Santiago de Compostela, Spain, last week when it went around a bend at twice the speed limit. Cassinello heard a loud vibration and then a powerful bump and then found himself surrounded by bloody bodies in wagon number nine. Shaking, he escaped the wreckage through either a door or a hole in the train—he cannot recall—then sat amid the smoke and debris next to the track and began to cry. Seventy-nine passengers died.

Cassinello doesn’t remember everything that happened to him. The same mechanisms that kept his brain sharp enough to escape immediate danger may also make it harder for him both to recall the accident, and to put the trauma behind him. "The normal thing is that the person doesn't remember the moment of the accident or right after," says clinical psychologist Javier Rodriguez Escobar of trauma therapy team Grupo Isis in Seville, who helped treat and study victims of the 2004 Madrid train bombings. That's because the mind and the body enter a more alert but also more stressed state, with trade-offs that can save your life, but harm your mind’s memory-making abilities.

As the train fell over, several changes would have swept through Cassinello’s body. His adrenal glands, near his kidneys, would have released adrenaline (also known as epinephrine) into his bloodstream. The adrenaline would have directed blood to the powerful muscles of his arms and legs, where it would help him escape the wreckage faster. The hormone would have raised his heart and breathing rates. It also would have stimulated his vagus nerve, which runs from his spine to his brain. Although adrenaline cannot cross the blood–brain barrier, the vagus can promote noradrenaline production in the brain. That hormone activates the amygdala, which helps form memories.

Just the right amount of noradrenaline, researchers have found, can boost memory storage; too much can destroy it. Figuring out the balance could allow researchers to harness the hormone. Neuroscientist Christa McIntyre at the University of Texas at Dallas and colleagues have been studying how the chemical shapes memory-making in rats (her team is planning a human trial). When the team stimulated rats’ vagus nerves the animals’ memories improved. McIntyre has to keep the dose low, however, because other experiments have shown that too much noradrenaline appears to impede memory-making. Researchers are still trying to determine whether the excess noradrenaline directly causes the memory lapses or if the hormone is associated with high stress levels that cause some other chemical system to interfere. "That's the part we don't really understand: if there's too much [noradrenaline] or if there's another system that kicks in and puts a brake on it," McIntyre says.

Cassinello's memory lapses may be due to a noradrenaline overflow. But there may be other explanations for the gaps in his memory. His brain may have narrowed his attention at the time of the crash to only those things that matter for survival, such as escaping the train, leading him to ignore things that do not, such as whether the path out of the train passed through a door or a hole. Researchers have shown that humans report selective hearing during stressful events and that stressed people pay attention to different things than do unstressed people (pdf).

Cassinello's uncle picked him up from the accident scene and drove him to a hospital for a checkup. Apart from a few minor scratches, he was fine. But Cassinello says he has flashbacks to the disaster. "The images of shattered people in my cabin and outside are in my head," he says. Flashbacks are a normal part of the stress response. If Cassinello is lucky, the flashbacks will fade within weeks as he learns to suppress the bad memories cued up by triggers such as the sound of a train.

That process is called fear extinction. McIntyre and colleagues want to be able to influence it, so as to better help victims of post-traumatic stress disorder (PTSD). Scientists could activate a trauma victim’s vagus nerve, amplifying the memory-writing process while the patient practiced healthy responses to a fear-inducing stimulus. If the process works, it could speed up recovery. Other researchers are working on drug-enhanced fear extinction using chemicals such as zeta inhibitory peptide (ZIP) or D-cycloserine. Another approach, called fear reversal, aims to provoke fear-inducing memories into a malleable state, such as all memories enter when we access them, and then changing them with the help of a different drug, propranolol, which interferes with protein formation, or even with precisely timed talk therapy aimed at blocking the reconsolidation of bad memories.

One thing that is almost certain is that his memories of the event will change with time. Studies after the September 11, 2001, attacks on the World Trade Center found that New Yorkers' reports of their experience of the attack changed over the years.

For now, survivors of traumatic experiences such as Cassinello can lean on the trauma therapists who rushed to Santiago after the crash. Some 70 to 80 percent of car accident survivors get away without PTSD, McIntyre reckons. As Rodriguez points out, however, most of those therapists are volunteers in town for a few days. It may take a few weeks or even months of therapy for patients to get past the worst of their experiences.

http://news.yahoo.com/train-thought-derailed-accident-affect-brain-214500284.html

My personal experience indicates that selective notice of sensory input in times of crisis is a major factor.  When I'm high on adrenalin, I feel no pain - I mean, I barely notice being kicked in the balls, for example, which has come in handy a time or two.  I just don't notice details not pertinent to the emergency, or that get in the way of doing what I have to.  It stands to reason that this is a useful survival trait.  And yeah; I never remember those high-adrenalin incidents with competent fidelity, which I 've always thought had interesting implications about a lot of witness testimony in criminal cases...

[JarlWolf]

And likewise, I can personally attest that your mind can become entirely reactionary during a crisis, especially if you are trained for it. But there is a horrible, horrible drawback to it; and that is while it can make sure you cope during a situation, and make sure they you focus on the task at hand to ensure your own survival, your senses and mind didn't completely ignore everything else going on around you and the emotions and trauma hits you after. And depending on what you did and the more time you brood on it, and what the action is itself it can be a serious weight on your psyche. I still feel like a monster for some of the things I've done, and I still feel a lot of pain for things that are long since past. Often I find with such things that yes, the coping mechanism helped me block out things at the time, but now it slowly comes back and at times you can transport back to the moment if there is an appropriate trigger to stir your memory. And the effects of triggering your memory can be unpredictable, and often chaotic and at least in my case, dangerous.

In my case it even affects my sleeping habits. I can't go to sleep without checking my entire house, and even then the slightest of noises wake me. I am terrified to go to sleep still because I have fears I won't wake up, that someone will slit me while im sleeping. And it tortures your mind, and body when you can't relax properly, while its not as bad as it used to be for someone like me a traumatic experience can seriously harm a persons perception as well. When I was raising my daughters I had to lock my door, because if daddy's little girls came bouncing ontop of his bed daddy might mistake them for someone else and needless to say that someone else was trying to hurt him. And that doesn't bode well for their safety. And I knew this would happen because I HAVE been alarmed like that before. And I am truly thankful it wasn't my daughters who experienced that, because I am not sure how they would have turned out if their father had attacked them in a semi conscious state. The thought of it terrifies me to be damned honest, I am just glad that their childhood wasn't butchered by that.

[Buster's Uncle]

Yeah; holding together in crisis only to fall to pieces afterwards - you're preaching to the choir.  It's still a superior adaption to that of people who can't defer dealing with the trauma.  But I can never understand thrill-seekers; the price of dealing with the crash afterwards is too high.

And of course, it's near impossible to disentangle, for those of us with problematic tempers, the emergencies with the rage incidences.  I was talking about a mix of the two myself, in my previous remarks.  Your body doesn't separate out the reason for the sudden adrenalin poisoning.

I had an incident back in college where I lost my temper with a guy, Adam, why isn't important, and shoved him - nothing much happened, but I was out of my mind with anger.  In the aftermath, I asked the people in the room "How'd my arm get all [intercourse]ed up?"  Turns out Jason, a little fellow who was in the room when it blew up, was trying to restrain me by pinning my arm around the corner of the passageway I was standing in, and I scratched up my arm against the cinderblock wall, straining to get at Adam - I vaguely remembered Jason doing that once I'd been told, but I guess I felt no threat from him and ignored it.  I was certainly feeling no pain, which is typical for me.

I've been lucky to have never hurt anyone who woke me up abruptly, but it's always been a danger.  I have gone to some trouble over the years to try to train my family to be careful of me until I've had time to wake up.  Before I got neurotherapy in recent years, I often couldn't form sentences until I got my morning coffee and an hour to myself.

Fortune hasn't always favored me, but it's good that I've never seen military service.  I have enough to cope with from a rough childhood, and didn't need all the issues that come with that added.

[Unorthodox]

Kinda depends on the training.  Part of the whole EMT training in me was triage and identification, taking in the whole of a situation to ensure my own safety, and that of the patient.  I can still recall vivid details of just about every major situation I had to respond to, the state the area was in, the wounds, and the coarse taken.  There is a very cold, calculated, practicality to it.  My kids say I'm not their dad when they've been wounded, I just flip off all emotion and go through the training.  I know there's several things I wouldn't have been able to cope with rationally otherwise.  Amputations are not pretty. 

This has even extended to my own injury on the production line (where I dislocated my thumbs).  My hand got sucked into a machine thanks to a faulty shutoff.  I had witnessed this happen to a person a week prior, and he had lost fingers, as your natural reaction is to pull your hands back out from the pain, which would have ripped my fingers off as well.  I remember that going through my head, and just shutting off the pain while I searched for the reverse button.  Called for a fill in, and walked calmly to the nurse.   I was able to give an in depth report of how and why this happened (something the other 2 injured couldn't), and where the fault was, thus preventing further injuries. 

6 broken bones and 2 dislocated thumbs, when the pain hit at the hospital I was nearly senseless. 

Ironically, I have nightmares of losing my hands now.  Coupled with my hands regularly going to sleep, if that happens in the night, it will wake me in a panic. 

[Buster's Uncle]

I'm like that with other people's emergencies, or when people assaulted me as a kid - really, any emergency where I wasn't already angry when it commenced.  I go all cold inside, excited, but highly motivated and in control.  I still get a very focused attention and somewhat selective memory, but mostly in a good way, and all the stuff with the no pain and the superstrength and lightning reflexes I don't normally have, as well.  I even tend not to lose it afterwards too badly.  I'm good at emergencies, and when I generally acquitted myself well, the boost to my self esteem did a lot to offset the adrenalin crash.  This varied wildly with the assaults, according to how intrinsically humiliating the encounter was, aside from whether I won the fight.

It's the times I get angry that I'm not wired to handle well...