Neurobehavioral Assessments of Cerebral Vasospasm - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 566

A great deal of evidence points to orbital PFC being involved in
reward processing. Much of this is due to the reliable fi ndings with
reversal learning and extinction tasks; see refs. ( 241, 246, 253, 254 ).
In reversal learning, subjects are typically given a choice between
two alternatives and are taught that one of the alternatives is asso-
ciated with reward. Once this association is learned, the contingen-
cies are reversed so that the selection of the previously rewarded
stimulus results in receiving nothing, whereas selection of the pre-
viously unrewarded alternative is now rewarded. Subjects with
damage to orbital PFC tend to have diffi culty with these reversals,
often perseverating on the previously rewarded stimulus. Similarly,
damage to orbital PFC also tends to result in sustained responding
in the face of extinction.

7.8.3. Orbital Prefrontal
Cortex

Key functions of medial prefrontal cortex, including the anterior
cingulate cortex, appear to be feedback and response confl ict moni-
toring, as well as the basic strengthening of responses in operant
conditioning, especially when there are multiple response options.
The relationship of medial PFC to feedback monitoring has been
seen in numerous studies, including a recent study in which feed-
backs for both the selected and the unselected response were rep-
resented by neurons in this region ( 255 ). Analogs of Stroop-type
tasks have also shown the involvement of medial PFC in the moni-
toring and resolution of response confl icts ( 238 ). For monkeys,
antisaccade tasks are popular for studying response confl icts, in
which monkeys must inhibit responding directly to a stimulus, and
must instead respond in the opposite direction ( 256, 257 ). Finally,
several studies have shown that damage to medial PFC reduces the
degree to which feedback is used by monkeys to guide their goal-
directed responses ( 258 ).

7.8.4. Medial Prefrontal
Cortex

Frontal polar cortex, or Brodmann's area 10, appears to be involved
in higher-order planning and reasoning; see ref. ( 239 ). Popular
tests of planning include analogs of the Tower-of-Hanoi problem,
in which a structure is built out of smaller parts, with numerous
constraints imposed, such as having to use certain parts in a speci-
fi ed order ( 239 ). The task requires individuals to maintain the
overall goal or plan of building the structure while at the same time
formulating subgoals based on adhering to the imposed constraints.
Recent evidence has also shown that frontal polar neurons are
involved in feedback monitoring, providing perhaps the fi rst
signals to control subsequent cognitive processing, decision
making, and action selection, especially in unexpected or complex
situations ( 259 ).
This section provided a short review of the many tasks available
to assess damage to the cerebral cortex in monkeys. A monkey
model of the impact of cerebral vasospasm on neural processing
offers not only a wide variety of more sophisticated and subtle tasks
to characterize specifi c cortical damage, but it may also provide the

7.8.5. Frontal Polar Cortex