In adolescence, the brain is wired to experience pleasure more intensely than before or after. Illustration by Édith Carron

C57BL/6J mice are black, with pink ears and long pink tails. Inbred for the purposes of experimentation, they exhibit a number of infelicitous traits, including a susceptibility to obesity, a taste for morphine, and a tendency to nibble off their cage mates’ hair. They’re also tipplers. Given access to ethanol, C57BL/6J mice routinely suck away until the point that, were they to get behind the wheel of a Stuart Little-size roadster, they’d get pulled over for D.U.I.

Not long ago, a team of researchers at Temple University decided to take advantage of C57BL/6Js’ bad habits to test a hunch. They gathered eighty-six mice and placed them in Plexiglas cages, either singly or in groups of three. Then they spiked the water with ethanol and videotaped the results.

Half of the test mice were four weeks old, which, in murine terms, qualifies them as adolescents. The other half were twelve-week-old adults. When the researchers watched the videos, they found that the youngsters had, on average, outdrunk their elders. More striking still was the pattern of consumption. Young male C57BL/6Js who were alone drank roughly the same amount as adult males. But adolescent males with cage mates went on a bender; they spent, on average, twice as much time drinking as solo boy mice and about thirty per cent more time than solo girls.

The researchers published the results in the journal Developmental Science. In their paper, they noted that it was “not possible” to conduct a similar study on human adolescents, owing to the obvious ethical concerns. But, of course, similar experiments are performed all the time, under far less controlled circumstances. Just ask any college dean. Or ask a teen-ager. I happen to have three adolescent sons and in this way recently learned about a supposedly fun pastime known as a “case race.” Participants form teams of two and compete to see which pair can drink its way through a case of beer the fastest. (To get the most out of the experience, I was told, it’s best to use a “thirty rack.”)

Every adult has gone through adolescence, and studies have shown that if you ask people to look back on their lives they will disproportionately recall experiences they had between the ages of ten and twenty-five. (This phenomenon is called the “reminiscence bump.”) And yet, to adults, the adolescent mind is a mystery—a Brigadoon-like place that’s at once vivid and inaccessible. Why would anyone volunteer to down fifteen beers in a row? Under what circumstances could Edward Fortyhands, an activity that involves having two forty-ounce bottles of malt liquor affixed to your hands with duct tape, be construed as enjoyable? And what goes for drinking games also goes for hooking up with strangers, jumping from high places into shallow pools, and steering a car with your knees. At moments of extreme exasperation, parents may think that there’s something wrong with their teen-agers’ brains. Which, according to recent books on adolescence, there is.

Frances Jensen is a mother, an author, and a neurologist. In “The Teenage Brain: A Neuroscientist’s Survival Guide to Raising Adolescents and Young Adults” (HarperCollins), written with Amy Ellis Nutt, she offers a parenting guide laced with the latest MRI studies. By her account, adolescents suffer from the cerebral equivalent of defective spark plugs.

“When we think of ourselves as civilized, intelligent adults, we really have the frontal and prefrontal parts of the cortex to thank,” she writes. But “teens are not quite firing on all cylinders when it comes to the frontal lobes.” Thus, “we shouldn’t be surprised by the daily stories we hear and read about tragic mistakes.”

“The Teenage Brain” retails a number of such stories, including several involving Jensen’s sons, Andrew and Will. One is about Will’s totalling of the family’s Dodge. (He miscalculates the time he has to make a left turn.) Another features Andrew, his girlfriend, and another girl, who has passed out in the back of their car. The two conscious adolescents keep hoping the third one will wake up. Jensen insists that they take the girl to a nearby hospital. There her stomach gets pumped; it turns out that she has downed seventeen Jell-O shots—perhaps more, she can’t really remember. Then, there’s the story of Dan, “an all-around great kid,” who, one summer night, gets drunk and, together with a bunch of friends, scales the fence at the local tennis club to take a 3 a.m. swim. The friends get out, get dressed, and rescale the fence, only to discover that Dan is no longer with them. When they return to the pool, they find him lying face down in it. (Readers will be reassured to learn that Will and Andrew, at least, made it through high school in one piece and went on to graduate from Harvard and Wesleyan, respectively.)

The frontal lobes are the seat of what’s sometimes called the brain’s executive function. They’re responsible for planning, for self-awareness, and for judgment. Optimally, they act as a check on impulses originating in other parts of the brain. But in the teen years, Jensen points out, the brain is still busy building links between its different regions. This process involves adding myelin around the axons, which conduct electrical impulses. (Myelin insulates the axons, allowing impulses to travel faster.) It turns out that the links are built starting in the back of the brain, and the frontal lobes are one of the last regions to get connected. They are not fully myelinated until people are in their twenties, or even thirties.

This is where parents step in. “You need to be your teens’ frontal lobes until their brains are fully wired,” Jensen writes. By this she seems to mean near-constant hectoring. Whenever she hears a story like the one about Dan, she rushes to tell Will and Andrew, and, whenever Will and Andrew screw up, she uses it as an opportunity to remind them that they, too, could wind up floating face down in a pool. (After the unconscious girl has been dropped off at the hospital, Jensen relates, she sits Andrew and his girlfriend down at the kitchen table and lectures them about “blood alcohol levels and the effects on coordination and consciousness.”) As a matter of principle, Jensen has attached a lock to the liquor cabinet in her own home. When her sons are invited to someone else’s house, she calls the kid’s parents to make sure there will be no unsupervised fun.

I feel compelled to confess that whenever I hear a grisly story involving a dead or maimed teen-ager, I, like Jensen, pass it on to my sons. However, I also feel I should point out that, in a book packed with charts and statistics, Jensen provides no empirical evidence that scare tactics work. From personal experience, I can say that the immediate response is not always encouraging. When I asked my sixteen-year-old twins how they’d react if I called their friends’ moms to enforce safe-party protocols, one of them said, “Why even have kids if you’re going to do that?”

Laurence Steinberg is a professor of psychology at Temple, a father, and the lead researcher on the inebriated-mouse study. He is also the author of “Age of Opportunity: Lessons from the New Science of Adolescence” (Houghton Mifflin Harcourt). Like Jensen, he believes that teen-age brains are different from yours and mine. But, where Jensen identifies the problem as loosely connected frontal lobes, Steinberg sees it as an enlarged nucleus accumbens.