We believe that the task goal in voluntary movements provides meaning to existing information sources in the environment and determines, in a dynamic way, the use and relative importance of these different sources. This task-centered meaning bridges the apparent controversy between what information is available in principle (i.e., specification), and what information is perceived.

Nunez's description of the brain as a medium capable of wave propagation has provided some fundamental insights into its dynamics. This approach soon reaches the descriptive limits of the brain as a physical system, however. We point out some biological constraints which differentiate the brain from physical systems and we elaborate on its consequences for future research.