io9: dopamine

The Secret Connection Between Dopamine And Fear

Annalee Newitz — Thu, 20 Aug 2009 13:05:44 PDT

Dopamine is infamous as a pleasure-inducing brain chemical: It's the neurotransmitter released when you smoke a cigarette or snort cocaine. But a new study published today shows that dopamine is also key to keeping people terrified for long periods.

Specifically, dopamine is responsible for making you remember frightening experiences in the long term, rather than forgetting them right away.

Researchers studied the effect of dopamine on rats who had been terrified by having their paws electrically shocked. What the scientists discovered was that dopamine had no affect on the rats' memories if it was given shortly after the shock. But if the rats were given chemicals that reduced the amount of dopamine absorbed by their neurons about 12 hours later - roughly the time it takes for the brain to consolidate long-term memories - they forgot the painful experience quickly and walked right onto the foot-shocking device again. However, rats who received chemicals 12 hours later that enhanced the amount of dopamine absorbed remembered the foot-shocking device far longer than they might have otherwise. Their fear of foot shock remained quite vivid.

Let this be a lesson to all authoritarian regimes who want to rule with fear and drugs. Feed your population with dopamine promoters 12 hours after the public executions. Their terror and awe will last a lot longer, and you'll get a bigger bang for each buck you pay your death squads.

via Science

Deprive Yourself of Sleep and Your Neurons Will Get You High

Annalee Newitz — Wed, 20 Aug 2008 07:00:00 PDT

People who are sleep-deprived often report getting a "second wind" where they suddenly wake up and feel great — though they are still too fatigued to do any major problem-solving. A group of researchers have discovered there's a good reason for this. Sleep deprivation floods your brain with dopamine, the very same hormone that amphetamines like crystal meth shoot into your neural receptors.

So basically you don't need that speed to stay awake. You just need to, well, stay awake. The researchers speculate that amphetamines emulate the body's natural response to sleeplessness, which is to boost your alertness with extra dopamine. Speed tricks your body into thinking it needs a boost after a sleepless night.

But there's a good reason why people don't get addicted to staying up all night. According to Science Daily:

The rise in dopamine following sleep deprivation may promote wakefulness to compensate for sleep loss. "However, the concurrent decline in cognitive performance, which is associated with the dopamine increases, suggests that the adaptation is not sufficient to overcome the cognitive deterioration induced by sleep deprivation and may even contribute to it," said study author [Dr. Nora] Volkow.

So I guess the message is that if you want to stay up all night, and keep that cognitive performance going, you'll have to turn to drugs. Or maybe you could just get some sleep.

One Sleepless Night Increases Dopamine in the Human Brain [Science Daily]

A New Street Drug That Boosts Your Brain's Ability to Get High

Annalee Newitz — Mon, 24 Mar 2008 17:00:11 PDT

It turns out the gateway drug for amphetamine addiction is a substance provided by your own brain. The culprit protein is called DAT, so named because it is a dopamine transporter — and dopamine is the feel-good, get-motivated neurotransmitter that keeps you happy, hungry, and full of energy. Just as some people are born with the ability to grow larger muscle mass than others, some are born with the ability to squirt more dopamine into their brains because they have a greater-than-average helping of DAT. People with elevated DAT levels are quite literally better at getting high than people with average levels. How do we know? A group of researchers in North Carolina and Pennsylvania recently bred a group of mice to have DAT levels three times above normal and then gave them speed. Here's what happened.

According to the Proceedings of the National Academy of Sciences:

Ali Salahpour and colleagues explored the impact of DAT levels on the response to amphetamines—a group of addictive chemicals closely tied with dopamine sensitivity. Amphetamines are used legally to treat ADHD, narcolepsy, and to suppress appetite, but are well-known as illicit "club" drugs and performance enhancers. To investigate the consequence of high DAT levels, the researchers developed transgenic mice with three-fold higher levels of DAT compared with unmodified animals. The authors discovered that the drug was more powerful in animals with more DAT. The dopamine-enhanced animals were more sensitive to the effects of amphetamines, becoming hyperactive and more rewarded by the drug, according to the authors.

Tinkering with DAT levels is something that researchers are already trying in order to deal with things like hyperactivity and depression. Now it seems there might be a street value for DAT-enhancers. Take a hit of DAT, snort a line of speed, and you'll get more bang for your buck. Image via Paul De Koninck.

Increased Amphetamine-Induced Hyperactivity [PNAS]

A Drug to Make You Stop Taking Drugs?

Annalee Newitz — Wed, 26 Dec 2007 11:15:09 PST

A new study reveals that people with addictive personalities also tend to have highly-developed "impulsivity" structures in their brains. Often their impulsive behaviors — and thus their tendencies to eat a zillion drugs — can be curbed with a little dopamine boost. Will we be seeing dopamine-primers and enhancers hitting the market for drug addicts? [Eurekalert]