Prefrontal cortex: the present and the future

In this chapter the current neuropsychological and physiological evidence linking lateral and orbital prefrontal cortex (PFCx) to human cognition and social 1837 interchange will be reviewed in an attempt to provide a summary of much of the work presented at the Rotman Frontal Lobe meeting and delineated in this book. We will begin with our view of the contributions of lateral prefrontal cortex to executive control. This book provides evidence of a remarkable convergence of lesion, electrophysiological and fMRI data on the role of lateral PFCx in inhibitory control, excitatory modulation, working memory and novelty processing. The electrophysiological data accrued from humans and animals provide important information on the timing of PFCx modulation of cognitive processing. This electrophysiological data is complemented by fMRI findings defining the spatial characteristics of PFCx involvement in a variety of cognitive tasks with evidence mounting for engagement of interleaved inhibitory and excitatory processes during a host of cognitive processes. Finally, the neuropsychological data provides the crucial behavioral confirmation of electrophysiological and functional magnetic resonance imaging (fMRI) findings obtained in normal populations. In our view the most complete picture will emerge from fusion of classic neuropsychological approaches informed by cognitive theory with powerful new techniques to measure human brain physiology. We first review the findings concerning the role of lateral PFCx in executive control of cognition and then discuss the 1838 relevant literature on the contributions of orbital PFCx to social and emotional control. This chapter will not address the role of medial PFCx cortex in various aspects of motor planning nor will we discuss language and PFCx, which is reviewed by Alexander in this volume. A possible separate role for the polar regions may exist, but the evidence currently is inadequate to introduce in this review.