Executive function and higher-order cognition: EEG studies


Multiple goals, from survival to pleasure, coexist at every given moment, and internal needs as well as external events act in a push–pull manner to bias behavior. To maintain optimal goal-directed behavior, a control (‘executive’) system is needed that will dynamically prioritize the processing of information as well as the planning of actions and their execution. In addition to direct motor planning, major components of this executive system are working memory, attention, and conflict/error monitoring. Working memory would allow maintaining a goal across time, as well as information required to achieve the goal. Selective attention (‘voluntary’ or ‘endogenous’ attention) would facilitate the processing of one stream of input and suppress another while involuntary attention mechanisms allow for changes in the environment, as well as changes in internal drives, to interfere with ongoing behavior in a rapid and flexible manner. A monitoring module is needed to assess the efficiency of the executed behavior so that behavior can be adjusted in an optimal way. Consequently, the executive system needs to interact with multiple sensory regions of the brain, as well as with motor output regions involved in orientation, locomotion, and speech. Event-related brain potentials (ERPs), recorded on the scalp (and recently also intracranially) have established scalp-recorded signatures of executive functions. The effect of brain lesions on these measures of electrical brain activity provides a window into the networks supporting the executive system. This article describes ERP studies conducted specifically with patients suffering from well-circumscribed brain lesions involving mainly the lateral prefrontal cortex (LPFC), a major hub of the executive system.