The biological constituents of learning are: neurons (brain cells), glia (supporting cells), and synaptic connections between neurons. Neurons hold information in the form of an electrical gradient across the cell membrane. An electrical gradient is a high concentration of a certain mineral – usually calcium or sodium. When the brain receives stimulus from sensory organs (eyes, skin, ears, etc), the electrochemical gradient of the affected neurons shift. This gradient is held in place by the glia until new stimulus reaches the brain and the gradient changes.
Neurons interact with each other by transferring their gradients through specialized terminals called synapses. Synapses “seek out” nearby neurons and share information with them in the form of electrochemical gradients. The gradient of nearby neurons changes as they connect with other neurons.
After repeated stimulus, neurons will begin to make these connections more quickly. We call this accelerated connective process learning. When your synapses fire extremely quickly based on certain stimulus, it means you’ve learned that stimulus well.