Basic Neurobiology of Huntington’s Disease
Part 2

What happens in the brain following the onset of HD?

How do nerve impulses work?

Nerve impulses are tiny electrical signals that travel through the nerve cells of the body, conveying information. Within a given nerve cell, the impulses move quickly from the receptor end of the cell which has small projections called dendrites. Dendrites, found on every nerve cell, extend out from the cell body and are responsible for receiving messages from other nerve cells. The impulses then travel down along the axon to the terminal branches. There, the impulses are carried across the gap to the next neuron by way of chemicals called neurotransmitters. These chemicals are capable of binding to receptors found in the dendrites of the next receiving nerve cell. Once a number of receptors on the receiving cell have chemicals bound to them, they trigger changes in the receiving neuron that enable it to send the electrical signal down its axon.

When that signal reaches the end of the axon, it again triggers the release of neurotransmitters that are then picked up by the next receiving nerve cell. The process repeats itself over and over in rapid succession, relaying the impulse along a sequential chain of neurons, until the impulse reaches its destination.

In short, neurotransmitters are the chemical messengers that nerve cells use to communicate. There are many different types of neurotransmitters, and each nerve cell responds differently to them. Some “excite” neighboring nerve cells, and send impulses scurrying along their axons where they release abundant neurotransmitters. Others “inhibit” adjacent neurons, and cause them in turn to release fewer neurotransmitters. The overall effect is a bit like Morse code: information is conveyed as modulated signals between neurons in the brain and nervous system.

For a more detailed explanation of the nerve impulse click here.

Last Modified: 9-13-02

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