Neurotransmitter

Otto Loewi's Nobel Prize-winning discovery came to him in a dream on Easter Sunday, 1921. He dreamed of an experiment to prove chemical transmission between neurons, woke up to jot it down, but couldn't read his notes the next morning. Fortunately, the dream returned the following night, and this time he rushed to his lab at 3 AM to perform the experiment that would revolutionize our understanding of how brain cells communicate.

Dopamine is famously called the "pleasure chemical," but this is actually backwards—it's released more intensely during the anticipation of reward than during the reward itself. This is why slot machines and social media are so addictive: the uncertainty creates constant dopamine spikes that keep us coming back. Parkinson's patients, who lose dopamine-producing neurons, don't just lose pleasure—they lose the ability to initiate movement, revealing dopamine's crucial role in motivation and action.

While electrical signals in neurons can travel at 120 meters per second, neurotransmitter communication across synapses takes only 0.5 milliseconds—yet this tiny delay is why we have consciousness. Without this brief pause, thoughts would cascade instantly through the brain without the chance for processing, decision-making, or the complex interplay between different brain regions that creates our inner mental life.

Your intestines produce more serotonin than your brain—about 90% of your body's total supply. This "second brain" in your gut contains over 500 million neurons and can function independently of your central nervous system, explaining why gut feelings are real and why digestive issues so often accompany mood disorders. The vagus nerve serves as a major communication highway between these two neural networks.

Most psychiatric drugs were discovered by accident rather than design. The first antidepressants were tuberculosis medications that made patients unusually happy, while lithium was tested as a sedative using uric acid from psychiatric patients' urine (the lithium salt was just easier to dissolve). These serendipitous discoveries led to our understanding that mental illness often stems from neurotransmitter imbalances—a concept that revolutionized psychiatry.

Your brain walks a constant tightrope between excitation and inhibition, with GABA acting as the primary "brake" neurotransmitter to balance glutamate's "accelerator" function. Too much excitation leads to seizures and anxiety; too much inhibition causes depression and cognitive sluggishness. This delicate balance is so critical that GABA receptors are the target of alcohol, benzodiazepines, and anesthetics—all substances that can literally turn off consciousness by tipping the scale toward inhibition.