What is learning, at a physical level in the brain?

Long-term learning is represented by the creation of strategic electrical wiring between neurons.

When the brain thinks about objects, concepts, associations, etc., it represents these things by activating different patterns of neurons with electrical impulses.

Loosely speaking, the brain’s working memory capacity represents the amount of effort that it can devote to activating these neural patterns and persistently maintaining their simultaneous activation.

Long-term learning is represented by the creation of strategic electrical wiring between neurons. This wiring is the physical makeup of long-term memory.

Whenever a neuron is activated with electrical impulses, the impulses naturally travel through its outward connections to reach other neurons, potentially causing those other neurons to activate as well.

By creating strategic connections between neurons, the brain can more easily, quickly, accurately, and reliably activate larger patterns of neurons.

Wiring induces a “domino effect” by which entire patterns of neurons are automatically activated as a result of initially activating a much smaller number of neurons in the pattern.

However, when the brain is initially learning something, the corresponding neural pattern has not been “wired up” yet, which means that the brain has to devote effort to activating each neuron in the pattern.

In other words, because the dominos have not been set up yet, each one has to be toppled in a separate stroke of effort.

This imposes severe limitations on how much new information the brain can hold simultaneously in working memory.