By Drs. David Niesel and Norbert Herzog
Some recent studies have revealed something we suspected but had not discovered about the brain. There are many types of neurons or nerve cells in the brain. We have known for years that there are predominantly two types of cells in our brains - neurons and glial cells. Glial cells provide nutrients to neurons, protect the brain from infectious disease microbes and remove dead cells, help with brain development, insulate neurons from each other to allow efficient electrical signal transmissions and provide a source of structural support for neurons.
Neurons provide those activities we normally associate with the brain. They are the basis for memory, provide conscious and unconscious thought and are the way that the brain transmits signals throughout the body. They can form neural networks providing the wiring that allows communication in the body. Most neurons are found in the brain or spinal column and have thin projections called dendrites which can extend more than 10 times the size of the neuron. Other cell projections called axons are the basis of nerve fibers and can extend over a meter in length. At the ends of these axons are junctions with the dendrites of other cells called synapses. Chemical signaling molecules called neurotransmitters are used to transmit signals across these junctions to the next neuron along a nerve fiber. In this way, the brain transmits signals that direct the activity of cells and tissues across the body. In a sense, neurons form the wiring of the body and provides the signals that keep us functioning in a coordinated fashion.
In a recent report, researchers have developed methods to identify different types of neurons in the brain. This work involved isolating the nucleus of single neurons in the cerebral cortex of the brain and comparing the genes that were active in these cells. So, the properties of any given cell are determined by which genes are active. They isolated the nuclei from 3200 neurons from 6 of the 50 different known areas of the cerebral cortex.
Based on the activities of genes, they could describe and classify neurons into 16 different subtypes and compare their properties. And further, these subtypes were clustered into different areas and layers of the brain suggesting that neurons that performed similar roles are located together. This "mapping" of the different neurons could pay big dividends in the future. Already these results can be used to assemble a reference map of the brain. This will permit scientists in the future to ask if specific brain diseases are associated with changes in the genes that these specific neurons are using. This could explain why these regions of the brain act differently and possibly what they do. This could lead to new advances in our understanding of neurodegenerative diseases like Parkinson's and Alzheimer's.
Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.