In the late nineteenth century, neurotroanatomists discovered that brain cells, or neurons, are independent units and not directly connected to each other. Physiologists C.S. Sherrington discovered a gap between neurons, which he called the synapse. But how do neurons communicate across the synapse? Some thought that there was an electrical current that ran between them, but the real answer cam from a dream.
in 1921, German phamacologist Otto Loewi dreamed how brain cells might communicate by releasing chemicals. He managed to write down what he had fantasized, but hew could not read his handwriting when he awoke the next morning. Fortunately, he had similar dream a second time and was able to remember it. To test the idea he had in his dream, he used the hearts of two frogs with the vagus nerve still attached. Loewi electrically stimulated one of the hearts and collected the fluid running through it. He then used that fluid to stimulate the second heart. He surmised that it was a chemical in the fluid that caused the effect; this chemical turned out to be acetylcholine, the first neurotransmitter ever discovered.
We now know that there are more than one hundred neurotransmitters in the brain, which are synthesized and stored in the presynaptic end of the neuron. When the neuron is stimulated, the neurotransmitters are released into the synapse and bring their chemical message to another neuron that has receptors specifically for that neurotransmitter. With the brain's one hundred billion-plus neurons, it is easy to imagine that billions of these messages are transmitted and received at any moment.
Each neurotransmitter has its own functions. Serotonin, for example, is one of the key neurotransmitters involved with sleeping , mood, and arousal level. It is best to keep in mind that none of these chemicals acts alone; the brain and its chemicals are more like a symphony than a violin solo.
in 1921, German phamacologist Otto Loewi dreamed how brain cells might communicate by releasing chemicals. He managed to write down what he had fantasized, but hew could not read his handwriting when he awoke the next morning. Fortunately, he had similar dream a second time and was able to remember it. To test the idea he had in his dream, he used the hearts of two frogs with the vagus nerve still attached. Loewi electrically stimulated one of the hearts and collected the fluid running through it. He then used that fluid to stimulate the second heart. He surmised that it was a chemical in the fluid that caused the effect; this chemical turned out to be acetylcholine, the first neurotransmitter ever discovered.
We now know that there are more than one hundred neurotransmitters in the brain, which are synthesized and stored in the presynaptic end of the neuron. When the neuron is stimulated, the neurotransmitters are released into the synapse and bring their chemical message to another neuron that has receptors specifically for that neurotransmitter. With the brain's one hundred billion-plus neurons, it is easy to imagine that billions of these messages are transmitted and received at any moment.
Each neurotransmitter has its own functions. Serotonin, for example, is one of the key neurotransmitters involved with sleeping , mood, and arousal level. It is best to keep in mind that none of these chemicals acts alone; the brain and its chemicals are more like a symphony than a violin solo.