38 PSYCHOLOGY
allowing for voluntary movements. It has association areas allowing for learning,
thinking, and memory. There are two speech areas allowing for language compre-
hension and language production. For example, Broca’s areais involved prima-
rily in language production. A group of structures in the cortex called the limbic
systemplay important roles in our motivational and emotional lives. For exam-
ple, damage to the limbic system can be associated with anhedonia(or ahedo-
nia), an inability to experience pleasure.(a) The “master gland” of the body is the.(b) One of the principal functions of the thalamus is to act as.
(c) What large structure of the brain is associated with our ability to think?Answers: (a) pituitary gland; (b) a relay center for the sense organs; (c) The cerebral
cortex.The Two Hemispheres of the Brain: Does the Right Side
Know What the Left Side Is Doing?
The prior description of the brain was based on a cross-section of the brain asso-
ciated with looking at a person’s profile. On the other hand, looking at the brain
from above, one discerns two cerebral hemispheres. These two hemispheres are
connected by a structure called the corpus callosum(“thick body”). The func-
tion of the corpus callosum is to provide a way for the two hemispheres to com-
municate with each other. In the vast majority of people the corpus callosum is
intact. Consequently, sharp differences between the way the two different hemi-
spheres work are not usually evident.
However, in a very small number of people the corpus callosum has been cut
as a treatment for intractable epilepsy. It is possible in such patients to study the
different ways the two hemispheres work. It is evident from studies of subjects
with a severed corpus callosum that the right hemispheremediates nonverbal
patterning—the kind of mental functioning required in drawing, making up a
melody, dancing, and creating visual images. The right hemisphere is sometimes
called the “romantic” hemisphere.
The left hemispheremediates verbal and mathematical thinking—the kind
of mental functioning required in writing, talking, scientific analysis, working an
algebra problem, and so forth. The left hemisphere is sometimes called the “logi-
cal” hemisphere.
The right side of the brain doesknow what the left side is doing if the corpus
callosum is intact—as it usually is.