Synapses and Neurotransmission

Messages are passed from neuron to neuron through synapses, small gaps between the cells, with the help of chemicals called neurotransmitters. To transmit an action potential message across a synapse, neurotransmitter molecules are released from one neuron (the "pre-synaptic" neuron) across the gap to the next neuron (the "post-synaptic" neuron). The process continues until the message reaches its destination.

There are millions and millions of connections between neurons within the spinal cord alone. These connections are made during development, using positive (neurotrophic factors) and negative (inhibitory proteins) signals to fine-tune them. Amazingly, a single axon can form synapses with as many as 1,000 other neurons.