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When a stem cell divides to produce an early progenitor cell, it is said to differentiate. Differentiation means that the new cell is more specialized in form and function. An early progenitor cell does not have the potential of a stem cell to make many different types of cells. It can only make cells in its particular lineage. Early progenitor cells can self-renew or go in either of two ways.
One type will give rise to astrocytes. The other type will ultimately produce neurons or oligodendrocytes. Not all neurons are successful in their journey. Scientists think that only a third reach their destination. Some cells die during the process of neuronal development. Mutations in the genes that control migration create areas of misplaced or oddly formed neurons that can cause disorders such as childhood epilepsy. Some researchers suspect that schizophrenia and the learning disorder dyslexia are partly the result of misguided neurons.
Once a neuron reaches its destination, it has to settle in to work. This final step of differentiation is the least well-understood part of neurogenesis. Neurons are responsible for the transport and uptake of neurotransmitters - chemicals that relay information between brain cells. Depending on its location, a neuron can perform the job of a sensory neuron, a motor neuron, or an interneuron, sending and receiving specific neurotransmitters.
In the developing brain, a neuron depends on molecular signals from other cells, such as astrocytes, to determine its shape and location, the kind of transmitter it produces, and to which other neurons it will connect. These freshly born cells establish neural circuits - or information pathways connecting neuron to neuron - that will be in place throughout adulthood.
But in the adult brain, neural circuits are already developed and neurons must find a way to fit in. As a new neuron settles in, it starts to look like surrounding cells. It develops an axon and dendrites and begins to communicate with its neighbors. Although neurons are the longest living cells in the body, large numbers of them die during migration and differentiation.
The lives of some neurons can take abnormal turns. Some diseases of the brain are the result of the unnatural deaths of neurons. This causes difficulty initiating movement. As a result, people twist and writhe uncontrollably. When these neurons die, people lose their capacity to remember and their ability to do everyday tasks.
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Physical damage to the brain and other parts of the central nervous system can also kill or disable neurons. These neurons may still live, but they lose their ability to communicate.
Scientists hope that by understanding more about the life and death of neurons they can develop new treatments, and possibly even cures, for brain diseases and disorders that affect the lives of millions of Americans. The most current research suggests that neural stem cells can generate many, if not all, of the different types of neurons found in the brain and the nervous system. Learning how to manipulate these stem cells in the laboratory into specific types of neurons could produce a fresh supply of brain cells to replace those that have died or been damaged.
Therapies could also be created to take advantage of growth factors and other signaling mechanisms inside the brain that tell precursor cells to make new neurons. This would make it possible to repair, reshape, and renew the brain from within. Box Bethesda, MD www. NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency.
Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history. Skip to main content. Enter Search Term Submit Search. The Life and Death of a Neuron. Request free mailed brochure Introduction The Architecture of the Neuron Birth Migration Differentiation Death Hope Through Research Introduction Until recently, most neuroscientists thought we were born with all the neurons we were ever going to have. The architecture of the neuron.
There are three classes of neurons: Birth The extent to which new neurons are generated in the brain is a controversial subject among neuroscientists. Migration Once a neuron is born it has to travel to the place in the brain where it will do its work. How does a neuron know where to go? What helps it get there? Scientists have seen that neurons use at least two different methods to travel: His poetically titled plays were among the first to introduce into U. O'Neill's plays were among the first to include speeches in American English vernacular and involve characters on the fringes of society.
They struggle to maintain their hopes and aspirations, but ultimately slide into disillusionment and despair. Of his very few comedies, only one is well-known Ah, Wilderness! Because his father was often on tour with a theatrical company, accompanied by Eugene's mother, O'Neill was sent to St. Aloysius Academy for Boys , a Catholic boarding school in the Riverdale section of the Bronx, where he found his only solace in books. Accounts vary as to why he left.
He may have been dropped for attending too few classes, [9] been suspended for "conduct code violations," [10] or "for breaking a window", [11] or according to a more concrete but possibly apocryphal account, because he threw "a beer bottle into the window of Professor Woodrow Wilson ", the future president of the United States. O'Neill spent several years at sea, during which he suffered from depression and alcoholism.
Despite this, he had a deep love for the sea and it became a prominent theme in many of his plays, several of which are set on board ships like those on which he worked. O'Neill joined the Marine Transport Workers Union of the Industrial Workers of the World IWW , which was fighting for improved living conditions for the working class using quick 'on the job' direct action.
After his experience in —13 at a sanatorium where he was recovering from tuberculosis , he decided to devote himself full-time to writing plays the events immediately prior to going to the sanatorium are dramatized in his masterpiece, Long Day's Journey into Night.
In the fall of , he entered Harvard University to attend a course in dramatic technique given by Professor George Baker. He left after one year and did not complete the course. O'Neill also had a brief romantic relationship with Reed's wife, writer Louise Bryant. His involvement with the Provincetown Players began in mid He was not left alone in the dining-room when the reading had finished. Some of these early plays began downtown and then moved to Broadway. O'Neill's first published play, Beyond the Horizon , opened on Broadway in to great acclaim, and was awarded the Pulitzer Prize for Drama.
FST: Spiritual Teachings: Journey of the Soul: Death and Dying
His first major hit was The Emperor Jones , which ran on Broadway in and obliquely commented on the U. The following year's A Moon for the Misbegotten failed, and it was decades before coming to be considered as among his best works. He was also part of the modern movement to partially revive the classical heroic mask from ancient Greek theatre and Japanese Noh theatre in some of his plays, such as The Great God Brown and Lazarus Laughed. In , O'Neill met Agnes Boulton , a successful writer of commercial fiction, and they married on April 12, They lived in a home owned by her parents in Point Pleasant, New Jersey , after their marriage.
O'Neill and Carlotta married less than a month after he officially divorced his previous wife. He moved to Danville, California in and lived there until In their first years together, Monterey organized O'Neill's life, enabling him to devote himself to writing. She later became addicted to potassium bromide , and the marriage deteriorated, resulting in a number of separations, although they never divorced.
In , O'Neill disowned his daughter Oona for marrying the English actor, director, and producer Charlie Chaplin when she was 18 and Chaplin was He never saw Oona again. He also had distant relationships with his sons.
Eugene O'Neill
Shane O'Neill became a heroin addict and moved into the family home in Bermuda, Spithead, with his new wife, where he supported himself by selling off the furnishings. He was disowned by his father before also committing suicide by jumping out of a window a number of years later. Oona ultimately inherited Spithead and the connected estate subsequently known as the Chaplin Estate.
After suffering from multiple health problems including depression and alcoholism over many years, O'Neill ultimately faced a severe Parkinsons -like tremor in his hands which made it impossible for him to write during the last 10 years of his life; he had tried using dictation but found himself unable to compose in that way. He managed to complete Moon for the Misbegotten in , just before leaving Tao House and losing his ability to write.
Drafts of many other uncompleted plays were destroyed by Carlotta at Eugene's request.
As he was dying, he whispered his last words: Born in a hotel room and died in a hotel room. Harry Kozol , the lead prosecuting expert of the Patty Hearst trial, treated O'Neill during these last years of illness.