186 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”It was immediately apparent that many of the physiologic reac-
tions, and the ensuing sensations of these reactions, so central to James’
peripheral theory of emotion, were identical to the motor (efferent) and
sensory (afferent) activities of the autonomic nervous system. Walter
Cannon, along with his student Philip Bard, was mainly responsible for
bringing the autonomic nervous system to light. They went one step
further by pointing out that one essential function of the sympathetic
system is to prepare the animal for a quick and violent action, the so-
called “fight-or-flight” response to a threat. Cannon and Bard identified
the hypothalamus as the brain center controlling the autonomic ner-
vous system. They also referred to the brain for “subtler emotions” such
as sustained feelings, a function that the James-Lange theory failed to
account for. Thus, the Cannon-Bard theory shifted the center of emo-
tion back to the brain.^8 The hypothalamus also mediates the secretion
of cortisol, the stress hormone from the adrenal cortex (an endocrine
gland at the upper pole of the kidney), through the hypothalamo-
pituitary-adrenal axis, though this is a much slower process than sympa-
thetic discharge.
9.5 Brain Centers Concerned with Emotion
In 1939, Kluver and Bucy demonstrated that bilateral removal of tempo-
ral lobes in monkeys produced dramatic behavioral alterations. Among
many changes, their affect flattened, they became tame and placid when
approached by humans, and their sexual appetite increased enormously,
including mounting inappropriate objects and members of other spe-
cies. Although the operation was crude and the lesion too extensive by
today’s standard, this was the first evidence that emotional centers are
present inside the brain.^9
The next moment of truth came in 1943, when reward centers were
serendipitously discovered. Olds and Milder inserted electrodes into
the rat brain. To their astonishment, they observed that stimulation of
some areas motivated the animal to incessantly self-stimulate (by press-
ing a bar to allow electric current to be delivered). The animal would