When response inhibition is followed by response reengagement: an event-related fMRI study.

In the course of daily living, changing environmental demands often make our actions, once initiated, unnecessary or even inappropriate. Under such circumstances, the ability to inhibit the obsolete action and to update behavior can be of vital importance. Previous lesion and neuroimaging studies have shown that the right prefrontal cortex and the basal ganglia seem to play an important role in the inhibition of already initiated motor responses. The present study was designed to investigate whether the neural activity of inhibitory motor control was altered if the inhibition process was succeeded by an additional process, namely the reengagement into an alternative action. Therefore, cerebral blood oxygenation during performance of a stop-change paradigm was registered in 15 male participants using event-related functional magnetic resonance imaging. Data analysis showed, that during successful and failed stopping and changing (response inhibition and subsequent response reengagement) of initiated motor responses a very similar network was activated including primarily the right inferior frontal cortex (IFC). Besides, stopping-related activation in right IFC was significantly greater for fast inhibitors than for slow ones. Results of the present study thus further underline the important role of right IFC in response inhibition and suggest that the inhibition process functions similarly regardless whether changing task demands require the complete suppression of an already initiated motor response or its suppression and a subsequent response reengagement into an alternative action.

The neuronal substrate of risky choice: an insight into the contributions of neuroimaging to the understanding of theories on decision making under risk.

This chapter provides an overview of studies in the field of neuroscience that investigate some of the processes and concepts of risk perception, risky choice, and decision making under risk. First, early studies in the field of neuroscience addressing the diminished decision-making abilities in lesion patients are presented. A classical task in this research field is described along with its neural implications. After this, the underlying model, its hypotheses, and neuronal implications are discussed. Different aspects within risky decision making, such as the influence of memory, inhibition, motivation, and personality, on risky choice and the respective underlying neuronal substrate are described. After this, studies of risky decision making in healthy subjects are reviewed. A selection of studies shows that theories focusing on cognitive aspects only have to be enriched in order to allow for additional aspects within risky decision making (e.g., emotion). Next, the classical economic approaches and the development of theories incorporating further aspects within economical decision making and the underlying neuronal substrate will be presented. Finally, research in the field of neuroeconomics, focusing on the role of social decision making and evaluative judgment within risky decision making, is reviewed.