Normal Communications between Neurons
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Neurons use electrical impulses to communicate from one end to the other through the axon. They are separated, however, by a gap called the synapse where electrical impulses do not work. The small gap where an electrical signal jumps from one neuron to another is called the synaptic cleft. This is a close up of the cleft between one neuron and another. Since the impulse cannot cross a gap as electricity, it crosses as a chemical message by means of "messengers" called neurotransmitters. One important neurotransmitter involved in the experience of pleasure is called dopamine and will be used to demonstrate normal communications here. |
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Here, dopamine, shown in yellow, is produced in the neuron shown at the top and packaged in containers called vesicles. As an electrical impulse arrives at the neuron's terminal, the vesicle moves to the neural membrane and releases its load of dopamine into the synaptic cleft. The dopamine crosses the gap and binds to receiver sites, or receptors, on the membrane of the dendrite of the next neuron. When dopamine occupies a receptor, various actions take place in that neuron: certain ions, shown in green, exit or enter, and certain enzymes are released or inhibited. The result is that a new electrical impulse is generated in this neuron, and the "message" continues on. After the dopamine has bound to the receptor, eventually it comes off again and is removed from the synaptic cleft and back into the first neuron by reuptake pumps. (For normal nerve transmission, it is important that the dopamine not stay in the cleft.) |
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We see what "normal communications" between the neurons looks like. Now let's see the influence and affects of external inputs. Our diet, medications, stress, and environment all play a part impacting these communications.
