Selective delay activity in the cortex: phenomena and interpretation.

The present article does not intend to present technical progress nor recent successes in accounting for experiments, as this issue of the journal presents a rich inventory. Rather, the paper presents a retrospective reflection on the history of the subject; on the relation between the different aspects of the concepts and the phenomena involved; on its strengths and weaknesses; and on some future prospects. It is a tribute to an extremely rich and growing wealth of physiological phenomena and of interpretative concepts. Yet the extent of achievement is used to expose open questions, which appear to become ever deeper. It is also an attempt to make the subject a matter of discourse between biologists and modelers, without the distraction of technical details.