Last in, first out: brain economy in times of limited resources

It has been argued that cognitive abilities that developed last ontogenetically are likely the first to become impaired when cognitive and/or physiological resources are compromised. In phylogeny as in ontogeny, the prefrontal cortex is a late developing region of the cortex. Late maturing areas of the dorso-lateral prefrontal cortex are primarily involved in higher executive functions. One crucial function of executive control is to enable self-control, i.e. the ability to inhibit automatic or habitual responses. Self-control requires effort and completing two successive self-control tasks, typically, produces a temporary drop in performance in the second task. It has been suggested that self-control requires an extensive amount of energy and when this energy is depleted, later self-control ability is adversely affected. In this talk, a series of experiments exploring the relationship between glucose availability and self-control performance using a neuro-cognitive approach will be presented. The data suggest that although frontal cortical areas are susceptible to limitations in fuel supply, level of motivation to perform a task can moderate the effect of impaired self-control performance following prior exertion. The results suggest that allocation of resources to limited-capacity systems is moderated by motivational factors. Putative underlying mechanisms regulating allocation of resources will be discussed.