Abstract
Behavioral and electrophysiological evidence implies that brains compute representations of aspects of the experienced world. For example, they compute the animal's position in the world by integrating its velocity with respect to time. Other examples are the learning of the solar ephemeris, the construction of a cognitive map, and episodic memory in food caching. Representations require a symbolic read–write memory that carries information extracted from experience forward in time in a computationally accessible form. The analogy between the architecture of computer memory and the genetic architecture suggests the sort of memory structure to be looked for in the nervous system.