Neuroscientist Marc Lewis on His First Acid Trip

Novelist Ken Kesey and his Merry Pranksters brought acid to the masses in their polychromatic bus. Ted Streshinsky / Corbis

For most of my late teens and 20s, I tried to rewire my brain by ingesting every drug I could lay my hands on. Which probably helps explain why I became a neuroscientist, studying the brain changes brought about by drugs and addiction.

My drug-taking adventures began in the late '60s—when the world seemed wide open, waiting to reveal its wonders. I had just arrived in Berkeley, Calif., and my newfound friends and I were spellbound by the mind-expanding potential of LSD.

Blast Off: My first acid trip was both wonderful and terrifying. I was in a friend's apartment, among a rag-tag assortment of hippie types, and I swallowed a little purple pill during a prolonged Monopoly game. About 45 minutes later, the room started to disintegrate. I had to stop playing; I could no longer read the numbers on the dice. The dice, the plaster walls, the chattering voices, the facial hair of my compatriots—each perceptual gestalt broke apart into its constituent details, moving, changing, swirling, arranging themselves into patterns of geometric beauty or turgid ugliness. My senses and thoughts were out of control, and the world rushed in relentlessly.

So this is what they mean by "better living through chemistry." LSD (lysergic acid diethylamide) goes to work in the brain by blocking serotonin receptors. Serotonin's job is to reduce the firing rate of neurons that get too excited because of the volume or intensity of incoming information. Serotonin filters out unwanted noise, and normal brains rely on that. So, by blocking serotonin, LSD allows information to flow through the brain unchecked. It opens up the floodgates—what author Aldous Huxley called the "Doors of Perception"—and that's just what it felt like the first time I took it.

Inner Spacemen: LSD was invented by the Swiss scientist Albert Hofmann in the 1930s, but its psychedelic properties were not apparent until he tried it on himself, in 1943, and thought he was going mad. Psychiatric researchers tried to treat disorders ranging from schizophrenia to alcoholism with LSD. The CIA and the U.S. military got into the act in the '50s and '60s, with the hope of manipulating potential informers or instilling mass confusion in enemy troops. But the effects of LSD remained elusive and unpredictable, and it was deemed more trouble than it was worth in government circles.

That didn't stop acid evangelists like Timothy Leary and Ken Kesey, who helped make LSD the emblem of a generation intent on change. For me and my friends, LSD became the key that could unlock perception and redefine human potential. So I took acid at least once a week and watched the grain of the sidewalk separate into rainbow fragments, or tossed in the surf of my own cognition as it swelled in profundity. I wanted to strip off my mental armor and let reality enter. And I didn't give up for several years, until acid finally became routine, and I got drawn toward darker adventures with addictive drugs, heroin among them.

Gravitational Shift: It's interesting to note that serotonin is once again the target of a culturewide chemical invasion—except that the serotonin drugs we favor today shift human experience in the opposite direction from LSD. SSRIs (selective serotonin reuptake inhibitors) like paroxetine (Paxil) and fluoxetine (Prozac) are the most prescribed pills in the U.S., used to treat depression, anxiety, PTSD, OCD, and undefined feelings of ickiness. Instead of getting rid of serotonin, these drugs block the reabsorption process so that serotonin keeps piling up in the synapses. The result: an extra-thick blanket of serotonin that filters out the intrusions of anguish and anxiety, making our inner worlds more secure. Instead of turning on, tuning in, and dropping out, they help us turn off, tune out, and drop in—into a solipsistic safety zone, protected from too much reality.

What do these newer drugs tell us about our culture and how we perceive our world? Apparently, now is not a time of exuberant exploration but a time to hunker down and play it safe. Instead of letting the world in, with all its uncertainties, we try to keep it out. And a barricade of serotonin makes that possible.

The drugs we create, the drugs we take, the drugs we abuse—they offer an idealized antidote to the cravings of our times. LSD was born from our craving for freedom. SSRIs reflect our need for security. As I discovered from my own explorations of inner space, molecular makeovers never quite do the trick. But they can show us where we are and where we've been.

Marc Lewis is the author of "Memoirs of an Addicted Brain: A Neuroscientist Examines His Former Life on Drugs" (PublicAffairs).