How do brain cells communicate with one another to produce thoughts, feelings, and behavior?

They signal to one another using a process called neurotransmission.

But the transmission of these important chemical messages could not occur without unique cellular structures called receptors (a molecule in cells that serves as a docking station for another molecule).

Neurotransmission begins when one brain cell releases a neurochemical into the synapse (the space in between neurons.) But for a neighboring cell to “pick up” the message, that neurochemical must bind with one of its receptors.

When an electrical signal reaches the end of a neuron, it triggers the release of tiny sacs that had been inside the cells. Called vesicles, the sacs hold chemical messengers such as dopamine or serotonin.

This drawing shows a synapse — the space between two cells. The chemical messenger dopamine is inside the top cell. Receptors on the bottom cell are waiting to receive it.
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As it moves through a nerve cell, an electrical signal will stimulate these sacs. Then, the vesicles move to — and merge with — their cell’s outer membrane. From there, they spill their chemicals into the synapse.

Those freed neurotransmitters then float across the gap and over to a neighboring cell. That new cell has receptors pointing toward the synapse. These receptors contain pockets, where the neurotransmitter needs to fit.

It’s a bit like a game of catch. The first cell releases the neurochemical into the synapse and the receiving cell must catch it before it can read it and respond. The receptor is the
part of the cell that does the catching.

Signals for all of our sensations — including touch, sight and hearing — are relayed this way. So are the nerve signals that control movements, thoughts and emotions.

Each cell-to-cell relay in the brain takes less than a millionth of a second. And that relay will repeat for as far as a message needs to travel.

In recent years, researchers have learned that receptors are just as important as neurotransmitters in maintaining a healthy brain. In fact, studies have demonstrated that receptors play an important role in mood, learning, and social bonds. Receptors also mediate structural plasticity or remodeling of brain circuits that may result in changes to the number and type of synapses.

This short video discusses synaptic transmission in a simple and clear way.

Adapted from Dana Alliance for Brain Initiatives