activity” has been considered to play a major role in the short-term maintenance of memories. Many studies since then have provided support for this view and greatly advanced our knowledge of the effects of stimulus type and modality on delay activity and its temporal dynamics. In humans, working memory has also been a subject of intense investigation using scalp and intracranial electroencephalography as well as magnetoencephalography, which provide estimates of local population activity. The published findings include reports of systematic changes (...) in signal amplitude during working memory in the theta, alpha, beta. (shrink)

The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of (...) activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed. (shrink)