Riddle is to conundrum as the frontal pole is to…?

This scientific commentary refers to ‘Reasoning by analogy requires the left frontal pole: lesion-deficit mapping and clinical implications’, by Urbanski et al . (doi:10.1093/brain/aww072). In this issue of Brain , Urbanski and co-workers make a key advance in respect of our understanding of how the prefrontal cortex (PFC) supports intelligent behaviour. It is one that may help solve a curious conundrum in research on the functions of rostral PFC. Rostral PFC is a very large brain region for which there are many names (including the ‘frontal pole’), all of which are rather imprecise, but generally approximate to Brodmann area 10 of the human brain. The conundrum is this: many human lesion studies over the past 60 years or so have suggested that large uncomplicated removals of this region, or damage to the connections to it, can cause little or no impairment on IQ tests (for review see Burgess et al. , 2012). Indeed, there are detailed reports of individual patients who have had almost complete excisions of rostral PFC and yet still score within the top 1% of the population on the most commonly used clinical IQ test (e.g. Patient AP; Shallice and Burgess, 1991). But more recently, several authors have suggested that this brain region is in fact involved in ‘intelligence’ (Colom et al. , 2007; Glascher et al. , 2010), based on evidence from both human lesion studies and functional neuroimaging. How are these discrepancies to be reconciled?One possible solution lies in the way that ‘intelligence’ is measured (Duncan et al. , 1995). There are, in broad terms, two predominant ways of conceiving of intelligence in the study of brain and behaviour. The first is to think of ‘intelligence’ as little more than an average of performance across a wide range of tasks that …