In this lesson we will review the role of the brain in the production and comprehension of
Language is modular in the sense that we covered in lesson 4.
language consists of several distinct, separable processes.
These normally work together in a
unified, coherent package and we seldom give conscious attention to what is going on while we
are engaged in a conversation.
But if something goes wrong, we can see the independence of the
Until fairly recently, we had to wait for something to go wrong in order to deduce
the brain mechanisms of language.
Now, however, we have access to a growing group of
investigations that use various non-invasive brain imaging technologies to see the brain while it
is engaged in some aspect of language.
Therefore, we will review both neuropsychological and
behavioral neuroscientific approaches to language.
The major organization of this lesson is to break language into its modules, beginning
with the major ones, speaking and comprehension. Within each, we will review more specific
At the end, we will use sign language studies to explore the specificity of these brain
regions for language.
Coherent speech requires that we select words from our vocabulary, and utter them
clearly in a sequence that is grammatically correct.
Individuals who have brain lesions due to
stroke may have troubles with all or parts of this process.
Known technically as
, speakers somehow access words from memory.
is most directly studied in the context of naming things or actions that are depicted in photos or
When certain brain areas are injured, deficiencies may occur in the retrieval process
and these deficiencies are often specific to certain word categories.
For example, a group of
researchers at the University of Iowa studied 127 persons who had lesions in some part of the
brain due to stroke.
They showed these people over 300 photos of well-known people, animals,
or tools and asked them to name the entity as specifically as possible (e.g., Santa Claus, squirrel,
or screw driver).
Of these people, 97 performed as well on this task as a group of control
individuals who did not have any known form of brain damage.
Of the 30 who were impaired in
the naming process, 29 had lesions only on the left side of the brain, although the size and
positioning of their lesions varied.
Some of these individuals had a naming deficiency that was