Quick buzz. Slow learning.

Beer and wine are quite possibly the oldest known man-made beverages.  Anthropologists have discovered beer jugs that date back to the Neolithic period (10,000 B.C.), and Egyptian pictographs clearly show that wine was a common beverage as early as 4,000 B.C.  Throughout history, alcohol has been used for both celebratory and practical reasons.  Today, consuming alcohol is a way to mark special occasions, socialize with friends, relax after a long week, and (sadly) ease the pain of rejection.

While responsible alcohol consumption can help enrich one’s life, it can be destructive if used to the extreme or without responsibility.  The practice of consuming excessive amounts of alcohol is called binge drinking.  Although it is not necessarily termed alcoholism, these intermittent surges of ethanol consumption perturb your reasoning and memory (as testified by those embarrassing photos or videos you untag the next day!) and invariably lead to a nasty hangover the next day.

Here are some neurological insights into the characteristics of binge drinking:

• What was I thinking? (Poor decision-making)

Executive functions, like decision-making and impulse control, are controlled by the prefrontal cortex, which shows disrupted activity in the presence of alcohol.

• What exactly happened? (Blackout)

High blood alcohol levels can interfere with the brain’s ability to transform short-term memories into long-term memories.  This is why you may be able to remember the names of the people you meet at a party while you’re there, but you can’t even remember meeting them the next day.

• Ugh, I feel terrible! (Hangover)

There are several major effects of ethanol that cause hangovers: (1) Ethanol is a diuretic and causes you to become dehydrated over time.  (2) Despite being a sedative, ethanol severely disrupts your normal sleep cycle, so you don’t feel as well-rested the next morning.  (3) Ethanol causes vasodilation, which can result in headaches.  (4) Changes in the metabolic state of the liver cause fluctuations in blood glucose levels, resulting in mood swings, irritability, and anxiety.

A new study in Current Biology examined the effects of binge drinking on learning and memory using fruit flies as their model system (our favorite this week!).  One group of larvae was given food spiked with alcohol while the control group was kept sober.  The larvae were trained on a negative association task, where they were required to learn to associate an attractive odor with an aversive heat shock stimulus.  If the larvae successfully make the association, they avoid the attractive stimulus.  Unsurprisingly, the intoxicated larvae were slow to learn this task.

After six days of binge drinking, the drunken larvae learned the task with the same aptitude as their sober counterparts.  Surprisingly, their performance was alcohol-dependent!  Inducing alcohol withdrawal in the intoxicated group of larvae plummeted their performance, which improved only when they were given alcohol again.  In other words, if the flies were drunk while learning the task, then the larvae had to be drunk to remember the same task later on!  These results suggest that the nervous system has the ability to continue to learn, despite the strong effects of alcohol, and that alcohol is required for recalling behaviors that were learned while under its influence.

We, at Knowing Neurons, promote responsible alcohol consumption and would never condone binge drinking as a viable way to cram for an exam.  But, it is interesting that this model shows a strong connection between ethanol exposure  and the ability to acquire and recall learned behaviors.