problem-solving. However, we suggest that the FPC function is restricted to the processing of simple cognitive branching, whereby only a single task can be maintained in a pending state at any one time. This hypothesis places severe serial and recursive constraints on human reasoning , problem-solving, and complex decision-making. Consistent with this view, it appears unlikely that the human brain has evolved to solve complex problems such as deciding the next move in a game of chess. Selective pressure to survive in a physically challenging environment may place other demands before the need for such higher cognitive faculties. Nevertheless , a capacity-limited FPC function may have endowed humans with two key adaptive advantages: on the one hand, an ability to pursue long-term behavioral plans and at the same time respond to demands of the physical or social environments; on the other hand, to explore any potential gain from the interposition of new task sets within ongoing behavioral routines or from the contingent recombination of previously established behavioral plans, as in genetic recombination mechanisms. Thus, the frontopo-lar cortex may have played an even more critical role in the gradual formation of complex be-havioral and cognitive routines such as tool use in individuals and societies, that is, in human creativity rather than complex decision-making and reasoning. By combining the models and tasks of Game Theory with modern psychological and neuroscientific methods, the neuroeconomic approach to the study of social decision-making has the potential to extend our knowledge of brain mechanisms involved in social decisions and to advance theoretical models of how we make decisions in a rich, interactive environment. Research has already begun to illustrate how social exchange can act directly on the brain's reward system, how affective factors play an important role in bargaining and competitive games, and how the ability to assess another's intentions is related to strategic play. These findings provide a fruitful starting point for improved models of social decision-making, informed by the formal mathematical approach of economics and constrained by known neural mechanisms.

No abstract

Many environmental stimuli present a quasi-rhythmic structure at different timescales that the brain needs to decompose and integrate. Cortical oscillations have been proposed as instruments of sensory de-multiplexing, i.e., the parallel processing of different frequency streams in sensory signals. Yet their causal role in such a process has never been demonstrated. Here, we used a neural microcircuit model to address whether coupled theta–gamma oscillations, as observed in human auditory cortex, could underpin the multiscale sensory analysis of speech. We show that, in continuous speech, theta oscillations can flexibly track the syllabic rhythm and temporally organize the phoneme-level response of gamma neurons into a code that enables syllable identification. The tracking of slow speech fluctuations by theta oscillations, and its coupling to gamma-spiking activity both appeared as critical features for accurate speech encoding. These results demonstrate that cortical oscillations can be a key instrument of speech de-multiplexing, parsing, and encoding.DOI: http://dx.doi.org/10.7554/eLife.06213.001