From contextual fear to a dynamic view of memory systems.

The brain does not learn and remember in a unitary fashion. Rather, different circuits specialize in certain classes of problems and encode different types of information. Damage to one of these systems typically results in amnesia only for the form of memory that is the specialty of the affected region. However, the question of how the brain allocates a specific category of memory to a particular circuit has received little attention. The currently dominant view (multiple memory systems theory) assumes that such abilities are hard wired. Using fear conditioning as a paradigmatic case, I propose an alternative model in which mnemonic processing is allocated to specific circuits through a dynamic process. Potential circuits compete to form memories, with the most efficient circuits emerging as winners. However, alternate circuits compensate when these 'primary' circuits are compromised.