Cognitive Neuroscience 59to corner A to be stimulated, we began trying to draw it away
to corner B, giving it an electric shock whenever it took a step
in that direction. Within a matter of five minutes the animal was
in corner B. After this the animal could be directed to almost
any spot in the box at the will of the experimenter. Every step
in the right direction was paid with a small shock; on arrival at
the appointed place the animal received a longer series of
shocks.
After confirming this powerful effect of stimulation of brain
areas by experiments with a series of animals, we set out to map
the places in the brain where such an effect could be obtained.
We wanted to measure the strength of the effect in each place.
Here Skinner’s technique provided the means. By putting the an-
imal in the “do-it-yourself” situation (i.e., pressing a lever to
stimulate its own brain) we could translate the animal’s strength
of “desire” into response frequency, which can be seen and
measured.
The first animal in the Skinner box ended all doubts in our
minds that electric stimulation applied to some parts of the brain
could indeed provide a reward for behavior. The test displayed
the phenomenon in bold relief where anyone who wanted to look
could see it. Left to itself in the apparatus, the animal (after about
two to five minutes of learning) stimulated its own brain regu-
larly about once very five seconds, taking a stimulus of a second
or so every time. (1956, pp. 107–108)We think now that this brain reward circuit Olds discov-
ered underlies addictive behaviors. It includes the medial
forebrain bundle (MRB) containing the ascending dopamine
(and other neurotransmitters) projection system to the nu-
cleus accumbens and prefrontal cortex. Activation of this sys-
tem appears to be a common element in what keeps drug
users taking drugs. This activity is not unique to any one
drug; all addictive drugs affect this circuit.
Another direction of research in motivation and emotion
relating to brain stimulation concerns elicited behaviors, par-
ticularly from stimulation in the region of the hypothalamus.
This work is in some ways a continuation of the early work
by Hess. Thus, Hess described directed attack, from hypo-
thalamic stimulation in cats, as opposed to the “sham” rage of
decerebrate animals and certain other brain stimulation stud-
ies (“sham” because the animal exhibited peripheral signs of
rage without integrated behavior) (see Hess, 1957). John
Flynn, in a most important series of studies, was able to elicit
two quite different forms of attack behavior in cats—one a
quiet predation that resembled normal hunting and the other a
rage attack (Flynn, Vonegas, Foote, & Edwards, 1970). Elliot
Valenstein analyzed a variety of elicited consumatory-like
behaviors—eating, drinking, gnawing, and so forth—from
hypothalamic stimulation and their possible relations to the
rewarding properties of such stimulation (Valenstein, Cox, &
Kakolweski, 1970).
Current focus in the study of motivated behaviors is on de-
tailed physiological processes, particularly involving mecha-
nisms of gene expression of various peptide hormones in the
hypothalamus and their actions on the pituitary gland, and on
descending neural systems from the hypothalamus that act on
lower brain systems to generate motivated behaviors (see
e.g., Swanson, 1991). But we still do not understand the
neural circuitries underlying the fact that seeing the bear in
the woods makes us afraid.COGNITIVE NEUROSCIENCEThe term cognitive neuroscienceis very recent, dating per-
haps from the 1980s. The Journal of Cognitive Neuroscience
was first published in 1989. Indeed, Posner and Shulman’s
comprehensive chapter on the history of cognitive sci-
ence (1979) does not even mention cognitive neuroscience
(human imaging techniques were not yet much in use then).
The cognitive revolution in psychology is treated in the chap-
ter by Leahey in this volume. Here we note briefly the bio-
logical roots of cognitive neuroscience (see Gazzaniga,
1995).
Karl Lashley was again a key figure. One of the most im-
portant aspects of cognitive neuroscience dates from the
early days at the Orange Park laboratory, where young scien-
tists like Chow and Pribram began studies of the roles of the
association areas of the monkey cerebral cortex in learning,
memory, and cognition.
The 1950s was an especially rich time of discovery re-
garding how cognitive function was organized in the brain.
Pribram, Mortimer Mishkin, and Hal Rosvold at NIMH,
using lesion studies in monkeys, discovered that the temporal
lobe was critical for aspects of visual perception and mem-
ory. Work with neurologic patients also played a critical role
in uncovering the neural substrates of cognition. One partic-
ular discovery became a landmark in the history of memory
research. “In 1954 Scoville described a grave loss of recent
memory which he had observed as a sequel to bilateral
medial temporal resection in one psychotic patient and one
patient with intractable seizures. In both cases...removals
extended posteriorly along the medial surface of the temporal
lobes...and probably destroyed the anterior two-thirds of
the hippocampus and hippocampal gyrus bilaterally, as well
as the uncus and amygdala. The unexpected and persistent
memory deficit which resulted seemed to us to merit further
investigation.”
That passage comes from the first paragraph of Scoville
and Milner’s 1957 report, “Loss of Recent Memory after
Bilateral Hippocampal Lesions.” This publication became a