Memory and Learning

Abstract

We can all agree by this advanced stage in our survey of neuroscience that the primary biological function of a nervous system, whether it is the simple nerve net of a jellyfish or the exquisitely complex human brain, is to monitor the conditions in and around its owner and to orchestrate its owner’s behavior to optimize its chances for survival and reproductive success. Much of this information processing and response selection capability of nervous systems appears to be built in to the basic plan through genetic evolution (e.g., respiratory reflexes). But nervous systems are endowed also with the ability to undergo some degree of physical alteration to provide flexibility in coping with the variability that might arise in their environment. The degree to which such alteration is possible is determined by the complexity of the nervous system, which in turn is determined by the ecological niche that its owner has come to occupy through the evolutionary process. The nerve net of the jellyfish will support only a handful of sensorimotor responses, which are stub- bornly resistant to change. By contrast, a broad ecological domain such as our own guarantees a variable environment, which favors a more complex and adaptive nervous system.