Chapter 16: The Frontal Lobes
thus derive their information from the object-recognition or motor streams of
Recall that both streams project to the prefrontal cortex, although to different
places (see Figure 16.3), which suggests temporal memory for both motor
and object information, although the memory will be localized in different
places in the frontal cortex. The dorsolateral areas are especially engaged in the
selection of behavior based on temporal memory.
People whose temporal memory is defective become dependent on environmental
cues to determine their behavior. That is, behavior is not under the control
of internalized knowledge but is controlled directly by external cues. One
effect of this condition is that people with frontal-lobe injuries have difficulty
inhibiting behavior directed to external stimuli.
In our dinner-party example, frontal-lobe patients would enter a shoe store
or chat with friends as they responded to environmental cues that they encountered.
We have probably all experienced occasions when the temporal organization
of our behavior failed and we were controlled by external cues rather
than internalized information. How many times have you started to do something,
been distracted by a question or event, and then been unable to recall
what you were going to do? (Sadly, this phenomenon increases with age, which
is not reassuring information about the state of one’s prefrontal cortex.)
One type of environmental cue is feedback about the rewarding properties
of stimuli. For example, if you imagine that a certain stimulus, such as a photograph
of your grandmo