The immune system: a matter of imprint on memory?

Nutrition Health Review, Wntr, 1989

The Immune System: A Matter of Imprint on Memory?

When a foreign substance (an antigen) invades the body, the immune system produces a specific antibody to counteract it. Does the immune system have its own memory?

Nobel Prize-winning immunologist Gerald Edelman finds similarities between the brain and the immune system. He considers them both powerful recognition systems, and both are superbly capable of storing information for future reference. Neither has encountered the knowledge before.

"The central problem for the organism," Edelman says, "is to classify things it could not have known." The production of a specific antibody leaves an imprint on the system that can serve as a memory for a second encounter and each encounter speeds the response as more cells are imprinted with the memory, Edelman notes, and this amplification process is a critical part of making the system succeed.

Edelman has proposed that a similar mechanism operates in the brain. He suggests that 50 to 10,000 neurons serve as the basic processing units of the brain. The neurons (nerve cells) are programmed from birth to form common code-recognizing groups.

According to the Edelman theory, a memory of some type is created at the point where nerve cell touches the synapse (a conductor to the next neuron) and the coded signal is passed on, leaving behind its individual imprint. Trillions of links between brain cells formed by neuron connections make up a network of brain circuits which Edelman terms the "primary repertoire."

Many different circuits of the primary repertoire recognize and react to a signal entering the brain. The process prepares "specialist" groups of nerve cells to respond quickly when the same signal enters the system again.

The Edelman theory of immune function based on a distinct memory system has been supported by the work of other researchers and is now classic in the field of neuroscience.

His most recent book, Neural Darwinism, postulates that the nervous system in each individual operates as a selective system resembling natural selection in evolution, but operating by different mechanisms.

The theory proposes to revise completely traditional concepts of memory. In Edelman's view, memory -- traditionally considered a storehouse -- is instead an ever developing and expanding process of recategorization. If Edelman is correct, his formulations have deep implications for the interpretation of many psychological states from perception to dreaming.