Frontal Lobe and the Cognitive Foundation of Behavioral Action

Summary

Motor representations are hierarchically organized in dorsolateral frontal cortex. The highest, most global plans and schemes of action appear to be represented in prefrontal cortex, intermediate ones in premotor cortex, and the most elementary motor acts in primary motor cortex. The confluence of external and internal inputs on frontal cortex leads to the activation of frontal neuron networks representing different categories of action. The activation of these networks is the physiological substrate for the initiation and execution of behavioral action.

Sequences of deliberate action require the coordinated interplay of all stages of the frontal hierarchy. Two cognitive functions for temporal integration operate at every stage: active short-term memory and preparatory set. Both are most apparent and can best be studied in the prefrontal cortex, where the longest action sequences are represented and coordinated and where cross-temporal contingencies are mediated. The prefrontal cortex, in cooperation with subcortical and posterior cortical areas, ensures the retention of sensory information for prospective action and the preparatory set of motor systems for its execution. Both of these functions of the prefrontal cortex have been substantiated by neuropsychology, reversible lesion and microelectrode recording in the monkey, and neuroimaging in the human.