Which neurons send messages to the brain

However, within any of these sensory or motor regions, there are tens or even hundreds of different types of neurons. In fact, researchers are still trying to devise a way to neatly classify the huge variety of neurons that exist in the brain. Looking at which neurotransmitter a neuron uses is one way that could be a useful for classifying neurons. However, within categories we can find further distinctions. Some GABA neurons, for example, send their axon mostly to the cell bodies of other neurons; others prefer to target the dendrites.

Furthermore, these different neurons have different electrical properties, different shapes, different genes expressed, different projection patterns and receive different inputs. In other words, a particular combination of features is one way of defining a neuron type. The thought is that a single neuron type should perform the same function, or suite of functions, within the brain. Scientists would consider where the neuron projects to, what it connects with and what input it receives.

In the spinal cord, it is pretty simple. But part of what gives the brain its complexity is the huge number of specialised neuron types. Researchers are still trying to agree on what these are, and how they should be classified.

QBI newsletters Subscribe. Help QBI research Give now. Skip to menu Skip to content Skip to footer. Illustration by Lydia V. The brain is what it is because of the structural and functional properties of interconnected neurons. The mammalian brain contains between million and billion neurons, depending on the species.

Each mammalian neuron consists of a cell body , dendrites , and an axon. When neurons receive or send messages, they transmit electrical impulses along their axons, which can range in length from a tiny fraction of an inch or centimeter to three feet about one meter or more. Many axons are covered with a layered myelin sheath, which accelerates the transmission of electrical signals along the axon.

This sheath is made by specialized cells called glia. In the brain, the glia that make the sheath are called oligodendrocytes, and in the peripheral nervous system, they are known as Schwann cells. The brain contains at least ten times more glia than neurons. Glia perform many jobs. Researchers have known for a while that glia transport nutrients to neurons, clean up brain debris, digest parts of dead neurons, and help hold neurons in place. Current research is uncovering important new roles for glia in brain function.

Ascending tracts carry sensory input upward to the brain. Descending tracts send motor commands downward to the body. When an electrical signal reaches the axons terminal of a neuron, it stimulates the release of special chemicals called neurotransmitters. Neurotransmitters travel across synapses to the other neurons or to target cells, stimulating or inhibiting signals and responses. Acetylcholine, epinephrine and norepinephrine, and serotonin are among the most common neurotransmitters.

Some neurotransmitters are more prominent in certain parts of the nervous system because they specialize in carrying messages within the brain, or between neurons and muscular tissue or other types of tissue. See more from our free eBook library. An article in Science Daily on a research study about the link between a neurotransmitter and alcohol dependence.

An essay on microglia in Science Creative Quarterly. Sight, Sound, Smell, Taste, and Touch. When you select "Subscribe" you will start receiving our email newsletter. Use the links at the bottom of any email to manage the type of emails you receive or to unsubscribe. See our privacy policy for additional details. Learn Site. Neurons and Neuroglia: The Cells That Make Up the Nervous System Structures of the nervous system, brain, spinal cord, peripheral nerves, and ganglia are formed from nervous tissue.