Let there be
In the beginning, the brain was a dark and shapeless void. Then scientists deployed dyes, and lo, the intricate branching of brain cells called neurons was revealed.
It was good but didn’t show which cells
rubbed branches with others.
After a time, scientists brought forth
electrodes and functional MRI machines
to eavesdrop on neurons’ electrical chatter. It was good, but the message was hearsay. It could not show that any specific
chitchat caused a particular behavior.
Then the scientists said let there be
light, and a new age of neuroscience
dawned. Now researchers create light-responsive molecules — or borrow them
from microorganisms — to insert into
animals’ neurons. And light shines upon
the molecules, giving scientists dominion over the brain cells’ activity.
Harnessing light’s power has given
birth to a burgeoning new field called
optogenetics, which allows scientists to
control neurons in freely moving animals. Although the technology is new, it
is already beginning to illuminate some
of the darkest corners of the brain, such
as the connections that guide movement
or make memories and the neuronal
circuits that go haywire in depression, addiction or schizophrenia. What
scientists learn from the light-aided
experiments may lead to refinements of
existing therapies or to new treatments
for nervous system disorders.
After its debut in 2002, optogenetics
went through a development period.
Scientists had to demonstrate that the
technology could change activity of
brain cells and behavior in moving animals. Only in the last two years have
Neurons (illustrated) made to produce
certain proteins can be activated by light.