This chapter presents a conceptual model of the representational and execut
ive functions of the cortex of the frontal lobe derived from empirical evid
ence obtained principally in the monkey. According to this model, the neuro
nal networks of the frontal lobe that represent motor or executive memories
are probably the same networks that cooperate with other cerebral structur
es in the temporal organization of behavior. The prefrontal cortex. at the
top of the perception-action cycle, plays a critical role in the mediation
of contingencies of action across time, an essential aspect of the temporal
organization of behavior. That role of cross-temporal mediation is based o
n the interplay of two short-term cognitive functions: one retrospective, o
f short-term memory or sensory working memory, and the other prospective, o
f attentive set (or motor working memory). Both appear represented in the n
euronal populations of dorsolateral prefrontal cortex. At least one of the
mechanisms for the retention of working memory of either kind seems to be t
he reentry of excitability through recurrent cortical circuits. With those
two complementary and temporally symmetrical cognitive functions of active
memory for the sensory past and for the motor future, the prefrontal cortex
secures the temporal closure at the top of the perception-action cycle.