FoundationalConceptsNeuroscience

Cocaine. Erythroxylum coca, native to South America, is another
example of a plant that has had a very long relationship with humans
for the physiological effects it produces (Fig. 9.3). The chemical co-
caine, isolated from the coca plant, was mentioned in Chapter 8 as an
example of a local anesthetic. However, more widely known and more
powerful than the local anesthetic effects are the stimulant effects of
the coca plant, first appreciated by native peoples of northern South
America thousands of years ago. The leaves of the coca plant are
chewed or used to make a tea, producing increased wakefulness, fo-
cused attention, decreased fatigue, and increased stamina.
Some of the effects of coca are similar to those of coffee, tea, and
other caffeine-containing plants, but coca also produces a distinctly
different experience. Other effects include decreased appetite, in-
creased positive mood, and stimulation of the sympathetic nervous
system (increased heart rate, vasoconstriction, opening up of the
bronchial airways and nasal passages, dilation of pupils). Coca is also
said to have beneficial effects on the digestive system. Native peoples
of South America have been using coca leaf for many centuries; to
them it is Mama Coca, a plant considered sacred and treated with re-
spect and reverence.
Coca, being a plant, contains hundreds of chemical constituents,
and among these there are no doubt several that have significant
physiological effects. Around 1860 German chemists isolated the
molecule cocaine from the coca plant and identified it as the primary
constituent responsible for the stimulant effects of the plant. Cocaine
as a purified and very potent chemical substance thus became avail-
able for human consumption. Perhaps nowhere is there a better ex-
ample of how the use of a plant can differ profoundly from the use of a
purified chemical constituent of a plant. It is easy to use the coca plant