The mysteries of the prefrontal cortex continue to fascinate new generations of psychiatrists, neurologists and cognitive neuroscientists, and this edited volume provides a welcome addition to the literature on this topic. It is more introductory (and much less expensive!) than Stuss & Knight's comprehensive Principles of Frontal Lobe Function (Reference Stuss and Knight2002), and several chapters would be suitable for undergraduate teaching. It is similar in format to Roberts et al.'s The Prefrontal Cortex: Executive and Cognitive Functions (Reference Roberts, Robbins and Weiskrantz1998), and serves as a useful update to this decade-old volume. Across the eight chapters, the reader is introduced to the core themes of anatomical, pharmacological and computational organization of the prefrontal cortex (Barbas, Wang), the neurodevelopment of the region (Dennis), and the wealth of neurocognitive functions associated with the prefrontal cortex, including working memory, long-term memory, inhibition and decision-making (Grafman, Ragland). The functional and anatomical heterogeneity of the region is emphasized throughout. Barbas proposes a tripartite organization of the frontal lobes into lateral, medial and orbital subregions; with dysfunction of these subregions resulting in behavioural symptoms involving cognitive control, motivation and emotion, respectively.
Fittingly, the volume highlights are provided by the two editors. Grafman's chapter provides a succinct overview of the major current theories of frontal lobe function, including the working memory model, the supervisory attentional system, the somatic marker hypothesis, and the adaptive coding model. There is a candid and insightful comparison of their strengths and weaknesses, considered in terms of processing approaches that associate the prefrontal cortex with specific functions like inhibition or working memory, compared to representational approaches that aim to establish the kinds of information that may be held in the prefrontal region.
The chapter by Risberg considers the evolutionary aspects of prefrontal cortex function, a perspective that has been generally overlooked in other edited volumes. Whilst it is controversial whether the entire frontal lobes are disproportionately larger in humans, there is strong evidence that frontal subregions like Brodmann Area 10 are larger than in our primate relatives. The possible adaptive strengths of these changes include tool-making, cooking, skilful hunting, teaching and socialization. However, these changes come at a cost: the large human brain is at increased risk for disease and injury, and psychiatric illnesses like schizophrenia may be inevitable side-effects of our evolutionary success.
The overall bias of the volume is towards human research, and neuropsychological deficits associated with frontal damage are particularly well-covered. Loring and Meador's chapter provides a historical overview of how our understanding of frontal lobe function has changed since Phineas Gage's seminal injury in 1848, and some subsequent influential case studies. They highlight how much of the research inspired by Gage has neglected to mention that initial descriptions focused on Gage's remarkable survival and cognitive integrity after such extensive brain damage. It was not until Harlow's 1968 report that Gage's personality change was noted, 7 years after Gage's death and 20 years after his accident.
Had Gage's accident occurred prior to adulthood – during the protracted period of prefrontal neurodevelopment – it is likely his social and neurocognitive abilities would have been more severely compromised. Dennis’ chapter reviews the complex effects of childhood damage to the prefrontal region, for example, in childhood traumatic brain injury or phenylketonuria. The psychiatric implications of prefrontal dysfunction are profound, and many psychiatric disorders may be better characterized as a gradual process of abnormal prefrontal neurodevelopment than an acute and localized prefrontal ‘lesion’.
A chapter of chapters touch upon the putative role of prefrontal disruption in the aetiology of schizophrenia (Barbas, Wang, Risberg, Ragland), and the final chapter by Brun & Gustafson provides a clear picture of the distressing and insidious effects of frontal dementias on patients and their families. My only complaint is that other disorders are generally overlooked. I would have welcomed more discussion of the potential roles of the orbital and medial prefrontal subregions in depressive, anxious and addictive disorders, where cognitive neuroscience has provided a wealth of research findings in recent years.
