Synapse

Charles Sherrington coined "synapse" in 1897 without ever seeing one—electron microscopes wouldn't exist for decades. He deduced these gaps must exist purely from timing experiments, noticing that nerve signals slowed down when passing between neurons. His linguistic choice was perfect: "synapse" from Greek meaning "to clasp together," capturing how neurons almost touch but never quite do.

Your brain contains roughly 100 trillion synapses—that's about 1,000 times more connections than stars in the Milky Way galaxy. Each pyramidal neuron in your cortex receives about 10,000 synaptic inputs, creating a computational network so complex that we're still decades away from fully simulating even a small piece of it. This microscopic infrastructure represents the most sophisticated information processing system we know of in the universe.

The synaptic gap is only 20-40 nanometers wide—so narrow that neurotransmitter molecules cross it in less than a millisecond. Yet this tiny space revolutionized evolution, allowing for the chemical modulation that makes learning, emotion, and consciousness possible. Without this gap, we'd be like jellyfish with simple electrical networks instead of beings capable of poetry and mathematics.

Newborn babies have far more synapses than adults—we actually lose about half of them during development in a process called synaptic pruning. This isn't damage but optimization: the brain eliminates weak connections while strengthening useful ones, sculpting itself based on experience. It's why children who learn languages early have such natural accents—their brains are literally rewiring themselves with each new word.

Synapses embody a fascinating paradox: they must be stable enough to store memories for decades, yet flexible enough to change with every new experience. Scientists discovered that the same synapse can strengthen during learning and weaken during forgetting—sometimes within minutes. This dynamic balance between persistence and adaptability is what allows you to remember your childhood while still learning new skills.

The discovery that mental illness often stems from synaptic dysfunction transformed psychiatry from guesswork to science. Depression, schizophrenia, and autism all involve altered synaptic transmission, leading to targeted medications that fine-tune neurotransmitter levels. What once seemed like mysterious afflictions of the soul turned out to be chemical conversations gone awry in spaces smaller than a virus.