Covek je ... secanje ili sta?

[S.]

Kaze:

"People tend to think about memory-altering drugs as science fiction, " says Richard Glen Boire from the Center for Cognitive Liberty and Ethics in Davis, California. Not true. These drugs will be available within five to 10 years and they will alter our lives entirely. In modulating a person's memories, we are talking about nothing less than altering the central part of what it means to be a human being." ...(he) nevertheless believes that individuals ought to have the right to manage their own memories. "I would not say that a Holocaust survivor should be prevented from wiping painful memories, just so that society can 'benefit' from their experience," he says. But he points out potential pitfalls. What if criminals took a memory-wiping drug so they could not recall their crimes and believed they never committed them? Should people be allowed to rewrite the memory of others?

Other experts are less comfortable with the notion. "I certainly wouldn't want to rewrite the past," says Eric Kandel, a Nobel prize-winning memory researcher at Columbia University in New York. "A person who has undergone something they feel guilty about is troubled by their memory for a reason. The nightmares make them a better person, because they realise the implications of their actions - it feels bad to hurt other people. I believe such drugs will make us worse as people."

--- Up to a third of those who experience a traumatic event first-hand go on to develop post-traumatic stress disorder (PTSD).
...
But how is it possible to target the fearful memories of PTSD without erasing other memories too? The answer lies in the special way that the brain processes emotionally charged experiences.

Stimuli from your sense organs are continuously entering your brain and converging on the thalamus, a clearing house for the senses. From there, the information is quickly dispatched along an express route to an almond-shaped region of the forebrain called the amygdala for a crude assessment of the "emotional quality" of the stimuli. If the amygdala recognises a potentially threatening component - such as the screeching brakes of a large vehicle or a curved shape on the ground that could be a snake - it triggers the body's stress responses: a typical "fight or flight" rush of adrenalin and noradrenalin.

"It's a quick and dirty response," says Pitman. "The amygdala triggers a rapid fear response to allow the body to take evasive action." Simultaneously to the "quick and dirty" response, other paths take signals from the thalamus to higher areas of the brain for more considered analysis of whether the stimuli represent a threat. "If, for example, the curve turns out to be a piece of hosepipe in the grass, then the prefrontal cortex reins in the amygdala response," Pitman says.

But if the stimuli turn out to represent a genuine threat, adrenalin and noradrenalin trigger a cascade of reactions in the amygdala, which then instructs the hippocampus - the brain's memory centre - to process the memory of those fear-inducing stimuli in a special way, imprinting them deeper than usual. "This stress-induced memory boost is a mechanism that evolved for survival," says Chris Brewin, a PTSD specialist at the Traumatic Stress Clinic in London. "Something very threatening needs to be remembered, so in the future, you're primed for action immediately."

Over the next few months, any stimulus similar to those experienced in the original trauma - even harmless ones - can trigger an exaggerated stress response in the amygdala. After a while most people learn that these stimuli are not a threat, and their brains make new pathways that override the old one, though they don't erase it. This process is called extinction. However, in some people - up to 30 per cent of those who directly experience a bombing, for example - the extinction mechanism doesn't work and the prefrontal cortex consistently fails to reign in the amygdala. The result is PTSD.


1.

...The idea originated in the 1990s when researchers experimenting on rats discovered that the enhancing effect of fear on memory formation could be reduced by beta-blockers a type of drug widely used to control blood pressure. Beta-blockers bind to receptors on the cell surface that normally bind adrenalin and noradrenalin, and so counteract their biological effects - including the effect on memory formation.

In 2001 Pitman put the idea to the test in humans. He set up an alert system with Massachusetts General Hospital's emergency room so that when a person was brought in after a traumatic incident, such as a car crash or a rape, they were given the option of taking part in his experiment. Those who agreed were given a tablet of either the beta-blocker propranolol or a placebo.

Pitman later asked the subjects to describe the traumatic event they had experienced and recorded their stories on to audio tape. Three months later he asked them to picture the event while listening to the recording, while he monitored their heart rate and other physiological reactions. In the placebo group, 43 per cent showed symptoms of stress such as increased heart rate and sweating. In stark contrast, none of the people who had received propranolol showed excess stress (Biological Psychiatry, vol 51, p 189).

2,3 i 4

Researchers at McGill University in Montreal, Canada, working with rats that had been conditioned to fear a harmless sound, discovered that each time the rats heard the sound, their fear memory became labile again for a short time and could be altered. This suggested that memories which appeared to be hard-wired long ago could be made pliable if they were recalled under emotive conditions. "This provides an important second window of opportunity," says Pitman.

This year Pitman has been carrying out a trial involving more than 20 people with long-standing PTSD who were given either propanolol or a placebo. Again, he recorded descriptions of each person's trigger event, and played back the recording three months later while measuring their physiological responses. He plans to announce the results in the new year.

Another team of researchers that includes Margaret Altemus of Cornell University in New York and Joseph LeDoux of New York University also plan to investigate propranolol treatment by allowing people with PTSD to self-administer the drug during a flashback, when the memory also becomes labile.

5, 6

The link between cortisol and PTSD was first noticed by Gustav Schelling, an intensive-care doctor at the Ludwig-Maximilian University Hospital in Munich, Germany. He treats a lot of people with septic shock, a potentially fatal condition caused by an overreaction of the immune system. These people often experience severe stress and pain, and it is not uncommon for them to go on to develop PTSD.

One of the treatments for septic shock is hydrocortisone, a synthetic version of cortisol and a potent immunosuppressor. Schelling noticed that PTSD seemed to be less common in those who had received hydrocortisone treatment. So he reanalysed the data from a small placebo-controlled trial his hospital had carried out into the effectiveness of hydrocortisone in treating septic shock. He found that seven of the 11 people (64 per cent) in the placebo group developed PTSD, compared with only nine out of 20 (45 per cent) of the hydrocortisone group.

The role of cortisol in PTSD is not fully understood, but the hormone is known to inhibit memory retrieval, possibly by diverting blood glucose away from the hippocampus and towards the muscles as part of the stress response. It's something actors are all too familiar with: when stage fright kicks in, their memory goes blank.

People with PTSD have been shown to have much lower baseline levels of cortisol in their brains. As a result, some researchers think, their emotional memories may be easier to retrieve, resulting in vivid flashbacks, or intrusions. Schelling thinks that disrupting memory retrieval during stressful events such as septic shock somehow protects against the development of PTSD.

Hydrocortisone is also being investigated as a treatment for established PTSD. Psychiatrist Dominique de Quervain of the University of Zurich in Switzerland gave three people with chronic PTSD a low daily dose of cortisol for a month and asked them to rate any change in the severity of their symptoms. All three reported that their symptoms were around a third less severe, with no side effects or alterations of other memories (The American Journal of Psychiatry, vol 161, p 1488).

7

Richard Bryant, a psychiatrist specialising in PTSD at the University of New South Wales in Sydney, Australia, is trying a different approach. He is using D-cycloserine (DCS), an antibiotic usually prescribed for TB. He chose the drug because one of its side effects is to promote the release of a brain chemical called glutamate, which is known to enhance learning. For this reason, the drug is sometimes administered to Alzheimer's patients as a memory booster. The idea is to use DCS alongside cognitive behavioural therapy to try to enhance the normal memory extinction process and prevent the development of PTSD in people who have recently witnessed traumatic events. The study is not yet completed, but the results so far appear impressive, he says.


Kao zakljucak: "The ability to block intrusive or traumatic memories may end some people's nightmares. But what of memories that are merely undesirable rather than pathological? Should humiliating, embarrassing or distressing episodes prompt us to swallow a liquor of forgetfulness?" Pa na pocetak teme - mogucnost odabira sta ce cuvati u secanju, a sta ne, ucinice coveka boljim ili ne?

[mac]

Preleteo sam preko teksta (stvarno ga ima), i koliko sam shvatio te droge te neće učiniti da nešto zaboraviš, nego da ne reaguješ emotivno kad se nečega setiš. Ako se to bude upotrebljavalo samo u izuzetno stresnim slučajevima, onda je sve u redu, ta droga je neka vrsta leka. Ali ako ga ljudi budu koristili zbog ljubavnih jada i stresa na poslu pretvorićemo se u ljude-robote. Duševni bol će se posmatrati kao nešto što se može i treba izbeći, ljudima će biti svejedno šta se oko njih dešava, oligarsi će lakše upravljati javnim mnjenjem, usamljeni glasovi protesta će biti istovremeno i ignorisani od strane naroda i lakše ućutkivani od strane oligarha.

Patnja pročišćuje dušu. Malo patnje čini čuda.

[Bab Jaga]

Smijem li napomenuti da skoro sva remek dijela umjetnosti stvarana zbog duševne boli?

[S.]

A, pa ima ga (teskta, mislim), ali nije moj i ne ide da ga kratim mnogo, niti da prepricavam.

Ja sam opet shvatila da najmanje jedna od tri do sada ispitivane supstance, DCS, ustvari ubrzava prirodni proces zaboravljanja. Pa i propranolol, ako te ne uznemirava sopstveni opsi traume neko vreme posle, mozda je i zato sto se bas i ne secas da se tebi dogodilo? Ne znam, odn. nisam sigurna kako sve moze da se tumaci.

Ovo je meni nategnuto: "What if criminals took a memory-wiping drug so they could not recall their crimes and believed they never committed them?" i malo... onako... Vise me brine sto ce, i u slucajevima zlocina kada je jos kljucno svedocenje zrtve (ah, do fully funcional C.S.I. uvek i svugde ima jos mnogo da prodje) , navedeni saobracajni udesi ili silovanje, memorija zrtve moci da se obrise - koliko god mogu da odobrim sa stanovista neke njene dobrobiti, toliko me brine realna mogucnost da krivac bude oslobodjen zbog nedostatka dokaza.  

Ja bih stavila gotovo potpunu jednakost izmedju coveka i secanja i stvarno me zanima sta cemo onda biti...

[mac]

To sa kriminalcima verovatno ima veze s tim kako detektivi vode istrage, sigurno će im biti teže da otkriju istinu od kriminalca koji je tu istinu zaboravio. I naravno, detektor laži, konačno ga naprave da valja, a sad se elegantno zaobilazi jednom pilulom.

Ja bih stavila gotovo potpunu jednakost izmedju čoveka i sećanja i stvarno me zanima šta ćemo onda biti...

Imaćemo neprilagođene pojedince koji će mozak pržiti pilulama zaborava, "humane" kriminalne sindikate koji će ti prijateljski ponuditi izbor izmedu pilule i metka, anti-pilule koje onemogućavaju dejstvo pilule ako se progutaju ranije (obavezne ako hoćeš da osiguraš svoje sećanje), kontra-pilule koje oporavljaju sećanje ako se progutaju "posle", super-pilule koje ti od mozga naprave švajcarski sir, sondaže uma koje su "jače" od bilo kakve droge, nano-procesorske implante koje omogućavaju "švajcarskom siru" da radi kako-tako... Čisti sjebapank!