July 7, 2010
by Jonah Lehrer
There's a fascinating article in the latest Vanity Fair (not online)
about the prevalence of LSD (aka lysergic acid diethylamide) among
movie stars in 1950s Hollywood:
Aldous Huxley was one of the first in Los Angeles to take LSD and
was soon joined by others, including the writer Anais Nin. The
screenwriter Charles Brackett discovered "infinitely more pleasure"
from music on LSD than he had ever before, and the director Sidney
Lumet tried it under the supervision of a former chief of psychiatry
for the U.S. Navy. Lumet says his three sessions were "wonderful,"
especially the one where he relived his birth...Another early
experimenter was Clare Boothe Luce, the playwright and former
American ambassador to Italy, who in turn encouraged her husband,
Time publisher Henry Luce, to try LSD. He was impressed and several
very positive articles about the drug's potential ran in his magazine.
There is no question that, at least for a period of time, LSD truly
transformed Cary Grant...Much to his friends' surprise, Cary Grant
began talking about his therapy in public, lamenting, "Oh those
wasted years, why didn't I do this sooner?"
"The Curious Story Behind the New Cary Grant," headlined the
September 1, 1959 issue of Look magazine, and inside was a glowing
account of how, because of LSD therapy, "at last I am close to
happiness." He later explained that "I wanted to rid myself of all my
hypocrises. I wanted to work through the events of my childhood, my
relationship with my parents and my former wives." More articles
followed, and LSD even received a variation of the Good Housekeeping
Seal of Approval.
Of course, celebrities no longer brag about their hallucinogenic
experiments. (Instead, we're stuck with the slow motion tragedy of
Lindsay Lohan.) Furthermore, the government now treats hallucinogens
(such as LSD and mushrooms) as legally equivalent to heroin, crack
and opium. Because LSD is a Schedule 1 drug, if you're arrested with
more than a single dose (roughly .5 grams), and it's your first
offense, the federal sentencing guidelines are as follows: "Not less
than 5 years, and not more than 40 years". State penalties are
similar, with possession typically leading to 1-3 years in jail.
(This despite the fact that study after study shows that prescription
drugs kill more people by overdose than illicit drugs.) If it were up
to me, our classification of drugs would depend largely on their
addictive potential, so that drugs with limited addiction potential
(such as LSD) were far less regulated than highly addictive
substances, such as crack, oxycontin, heroin, etc. But don't get me
started on our endless war on drugs, which is an incoherent disaster.
Back to LSD. Because the drug is so tightly regulated, there has been
minimal research on how the drug works in the brain. Just look at
these search results: The most cited papers are more than thirty
years old. (One scientist I talked to last year said the two main
disincentives to use LSD in the lab were the lack of grants - the big
funding institutions are only interested in addictive drugs - and the
paperwork.) The end result is that we really don't know how LSD
alters our sensory experience, except that it binds to a vast array
of G-protein coupled receptors, including every dopamine receptor
subtype and various serotonin receptor subtypes. All this excess
neural activity leads to excitation in the upper echelons of the
cortex, such as layers IV and V. And, somehow, those squirts of
chemical lead people to conclude that they've found the secret of the universe.
What's unfortunate is that LSD could be a powerful experimental tool.
And not in the Timothy Leary sense: I'm talking about rigorous
investigations into the neural substrate of consciousness. After all,
one of the challenges of investigating human consciousness is that
it's a continuous stream. As William James noted in 1890,
"Consciousness does not appear to itself chopped up in bits. Such
words as 'chain' or 'train' do not describe it fitly as it presents
itself in the first instance. It is nothing jointed; it flows. A
'river' or a 'stream' are the metaphors by which it is most naturally
described." The paradox, of course, is that the brain is composed of
a trillion different joints, a seeming infinitude of binary neurons
switching on and off. So how does that create this? How does three
pounds of wet stuff give rise to the ceaseless cinema of subjective
To begin to answer this profound mystery - and it is the mystery of
modern neuroscience - researchers have come up with a clever set of
experimental paradigms. My favorite is Christof Koch's version of
binocular rivalry. In theory, binocular rivalry is a simple
phenomenon. We have two eyeballs; as a result, we are constantly
being confronted with two slightly separate views of the world. The
brain, using a little unconscious trigonometry, slyly erases this
discrepancy, fusing our multiple visions into a single image.
But Koch throws a wrench into this visual process. "What happens," he
wondered, "if corresponding parts of your left and right eyes see two
quite distinct images, something that can easily be arranged using
mirrors and a partition in front of your nose?" Under ordinary
circumstances, we superimpose the two separate images from our two
separate eyes on top of each other. For example, if the left eye is
shown horizontal stripes and the right eye is shown vertical stripes,
we will consciously perceive a plaid pattern. Sometimes, however, the
brain gets a little confused, and decides to pay attention to only
one of our eyes. After a few seconds, we realize our mistake, and
begin to pay attention to our other eye. As Koch notes, "The two
percepts can alternate in this manner indefinitely."
The end result of all this experimentally induced confusion is that
the subject becomes aware - if only for a moment - of the artifice
underlying perception. We realize that we have two separate eyes,
which see two separate things. Koch wants to know where in the brain
the struggle for ocular dominance occurs. Which neurons decide which
eye to pay attention to? What cells impose a unity onto our sensory disarray?
This is an elegant experimental paradigm. But it's also profoundly
limited. Even if we can locate the cells that govern binocular
rivalry, that's only a single "neural correlate of consciousness". It
remains entirely unclear if those to-be-determined cells in the
visual cortex govern all visual experience, or just the
contradictions between our eyeballs.
And this leads me back to LSD. Here's a compound that can
consistently alter our entire sensory experience, so that the brain
is made aware of its own machinery. We see ourselves seeing the
world. (I wish Kant had tried LSD - he would have loved it.*) From
the perspective of neuroscience, the hallucinogen is like a
systematic version of binocular rivalry. If we knew how LSD worked,
we might also gain insight into how ordinary experience works, and
how that chemical soup creates the feeling of this, here, now. In
other words, the molecular "joints" tweaked by the illegal compound
can tell us something very interesting about the source of our
unjointed stream of consciousness. Cary Grant was on to something.
*Kant: "The imagination is a necessary ingredient of perception itself."