Scientific American Special - Secrets of The Mind - USA (2022-Winter)

SCIENTIFICAMERICAN.COM | 27

Illustration by Zara Picken

Electrodes that stimulate brain tissue reveal

the topography of conscious experience

By Christof Koch

Consider the following experiences:

● You’re headed toward a storm that’s a couple of miles away,
and you’ve got to get across a hill. You ask yourself: “How am
I going to get over that, through that?”
● You see little white dots on a black background, as if looking
up at the stars at night.
● You look down at yourself lying in bed from above but see
only your legs and lower trunk.

These may seem like idiosyncratic events drawn from the vast
universe of perceptions, sensations, memories, thoughts and
dreams that make up our daily stream of consciousness. In fact,

each one was evoked by directly stimulating the brain with an elec-

trode. As American poet Walt Whitman intuited in his poem “I Sing

the Body Electric,” these anecdotes illustrate the intimate relation-

ship between the body and its animating soul. The brain and the

conscious mind are as inexorably linked as the two sides of a coin.

Recent clinical studies have uncovered some of the laws and

regularities of conscious activity, findings that have occasionally

proved to be paradoxical. They show that brain areas involved in

conscious perception have little to do with thinking, planning

and other higher cognitive functions. Neuroengineers are now

working to turn these insights into technologies to replace lost

The

Brain

Electric