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The Brain and Behavior        57

in rats, he found a decrease in their efficiency proportional
to the total amount of tissue removed. His experiments failed
to demonstrate special significance for any particular area of
the cortex. The results of removing cortical tissue from apes
and humans, however, can not be understood in terms of this
simple quantitative rule.

Operations on the primate sensory or motor areas result
initially in some form of sensory deficit or paralysis. Penfield
& Rasmussen (1950) report that the removal of the whole
sensory projection area from one hemisphere of the cortex
results in the loss of the sense of movement and of position
in space of the arm and leg on the opposite side. Evidence
documenting anesthesia for the area is contradictory, but it
is clear that there is no permanent loss of the appreciation of
touch, pain, or pressure. Total removal of the motor area in
one hemisphere results in complete paralysis of the arm and
leg on the other side, which may be accompanied by spastic-
ity of those limbs. However, in a comparatively short time
some movement is again possible, and, although the process
of recovery is slow, virtually complete use of the limbs has
been reported for some patients in less than a year. In other
cases recovery never seems to be complete.

Franz (1929) reports that recovery from surgically induced
paralyses in monkeys usually takes nine to twelve months.
Using systematic exercising techniques coupled with im-
mobilization of the unaffected limbs, he found recovery was
substantially complete within thirty days. Application of
similar exercising procedures to human subjects with paraly-
ses of four or more years duration yielded similar results. Pa-
tients whose aims and legs had been useless became able to
use them well enough for running, playing baseball, or sew-
ing. In another kind of experiment Jacobsen (1934) removed
the part of the motor area involving the forelimbs in chim-

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