Development of Dendritic Spines :: Biology Essays Research Papers

Development of Dendritic Spines Neurons have the capability of forming spiny outgrowths on dendrites that are associated with neuroplasticity. Stimulation, especially during post-natal development can lead to activation in the brain, referred to as Long Term Potentiation (LTP), associated with the growth of spines. These dendritic spines, which can number thousands to a single neuron, can have synaptic heads. Greater than 90 percent of synapses in the brain occur on them (1) . Through experimentation it has been found that a spine's glutamate receptors, calcium concentrations, and actin can affect its shape, length, and even presence on a dendrite. In general terms, how do dendritic spines develop and what do they affect in the brain? When a neuron is first formed it does not yet have dendrites, and therefore also does not have dendritic spines. Dendritic filopodia are formed from the dendrites first and then convert into spines after being innervated by synaptic fibers. Spines on different types of neurons attain their peak actin density at different times. Fewer spines are present in adults than children and there is a peak growth time during post-natal development. Adult brains show up to 50% fewer spines than developing brains (2) . Brain disorders, such as strokes, epilepsy, and forms of mental retardation like Fragile X, have been connected to deformations of dendritic spines or the total absence of them on certain neurons. Spines are predominantly found at excitatory synapses where inputs from many areas of the brain arrive. Initially during spine formation N-methyl-D-aspartate (NMDA) is the main growth and development regulator. NMDA is a glutamate receptor found at excitatory synapses in most neurons in the mammalian brain. It contains channels permeable to calcium ions. Ions can accumulate and initiate currents at the head of the spine where the calcium channels are located, separate from the shaft of the dendrite. Weak calcium-induced currents affect individual spines whereas stronger currents can summate to affect multiple spines as well as areas of the dendrite's shaft. LTP is a strengthening of the synaptic connections which occurs when spines are formed. There are several steps to achieve a current in a spine. Magnesium ions block the NMDA receptor sites, but are displaced when a stimulus, such as caffeine, depolarizes the receptor. Calcium ions are then able to pass through and collect within the spine. Once the amount of ions reaches a threshold level the LTP is generated.

Plato Defends Rationalism

Plato Defends Rationalism Plato was a highly educated Athenian Philosopher. He lived from 428-348 B. C. Plato spent the early portion of his life as a disciple to Socrates, which undoubtedly helped shape his philosophical theories. One topic that he explored was epistemology. Epistemology is the area of philosophy that deals with questions concerning knowledge, and that considers various theories of knowledge (Lawhead 52). Plato had extremely distinct rationalistic viewpoints. Rationalism is the claim that reason, or intellect, is the primary source of our fundamental knowledge about reality (55).By examining Plato’s philosophical position on the three basic epistemological questions, as well as analyzing his ability to justify the three anchor points of rationalism, it is clear to see that Plato was successful in defending rationalism. There are three basic questions that are the basis for determining the difference between each of the epistemological viewpoints. The first of these is: Is knowledge possible? In order to understand exactly what is being asked here, it is important to consider the agreed definition of knowledge as being a â€Å"true justified belief† (53).Plato believed that yes, it is possible to have knowledge. He claimed that as long as one has the ability to recognize something as false, they are capable of having knowledge. The second question is: Does reason provide us with knowledge of the world independently of experience? Plato would also answer yes to this question as well. Many objected to this, believing that knowledge was a result of sense experience rather than reason. Plato examined this theory (empiricism); he argued that, because the physical world is subject to change, there can be no real truth in knowledge that is based solely on one’s senses.He then used the examples Justice, Goodness, and Equality to justify his argument that there are some things that we cannot come to know through experience alone, th us casting doubt on the empiricist theory. Plato expands on the teachings of Socrates, and acknowledges the concept that we already have ideas or principles that are contained in our mind prior to experience, called innate ideas (73). The third and final question is: Does our knowledge represent reality as it really is? To this question, he would answer yes. Plato’s distinction between innate ideas and sense experience bring us to understand his true sense of reality.Our innate ideas are the foundation from which we are able to possess rational knowledge. Rational knowledge, as Plato explains, gives us the ability to differentiate between invariable â€Å"Forms† (Universals) and the ever changing characteristics that are recognized through sense experiences. Plato believes that knowledge of Universals provide us with knowledge of the fundamental features of reality, which are nonphysical, eternal, and unchanging (81). The three anchor points of Rationalism expand on th e question discussed above, Does reason provide us with knowledge of the world independently of experience?The first anchor point is: Reason is the primary or most superior source of knowledge about reality (72). Plato proves this point to be true by determining that it is through unchanging, Universal knowledge, that we come to find reality. The second anchor point is: Sense experience is an unreliable and inadequate route to knowledge (73). Plato questions the reliability and adequacy of sense experience, due to the fact that there are things that we are simply unable to experience in the physical world. If knowledge comes strictly from experience, and we are unable to experience some things, how is it that we come to find such knowledge?Plato also argues that sense experiences are subject to individual interpretation, and are ever changing. Knowledge cannot be based on inconstant perception. The final anchor point of rationalism is: The fundamental truths about the world can be k nown a priori (independently of, or prior to, experience): They are either innate or self-evident to our minds (73). Plato believed that knowledge was contained in our soul from preexistence, and was independent of human experiences. He came to the conclusion that it is from these innate ideas that we are able to recognize reality.Plato’s view on epistemology is extremely consistent with that of rationalism. He was able to successfully justify his beliefs, not only by proving his theory, but also by disproving alternative theories. Plato recognized the fact that knowledge is possible. He believed that the ability to identify something as false can only come from knowing truth. This was the first step in his philosophical journey. In his quest to determine the source, and explore the characteristics of knowledge, he made several valid arguments.Plato’s strongest argument was that we cannot base our knowledge directly on experience, because there are circumstances in whi ch our senses do not provide us with reliable truths. Not only did this make it apparent that experience is not concrete enough to act as a basis for knowledge, thus disproving the imperialistic theory, but it also helped justify his theory of Universals. Plato was able to prove that reason, by way of innate ideas, leads us to knowledge, as it was defined above, a true justified belief.This rational knowledge, in turn, leads us to the knowledge of reality. Plato spent much of his life studying philosophy, and the concept of knowledge. After finding fault in other epistemological theories, he was led to develop a philosophy of his own. Plato’s approach toward epistemology was considerably different from that of other philosophers in his day. His rationalistic viewpoints were extremely influential. He brought light to the concept of Universals, which had a great impact on the work of philosophers after him.Plato was able to explain knowledge from all aspects, which set him apar t from others. Plato was not only able to conclude that knowledge is possible, he was also able to explain how knowledge is obtained. By examining Plato’s philosophical position on the three basic epistemological questions, as well as analyzing his ability to justify the three anchor points of rationalism, it is clear to see that Plato was successful in defending rationalism.Works Cited Lawhead, William F. The Philosophical Journey: An Interactive Approach. 5th ed. New York: McGraw-Hill, 2011. 52-81. Print

Love Upon First Sight By Cults - 800 Words

Farouk Shousha Prof. Webb ENG 101 08 October 2015 Love Upon First Sight The music video â€Å"Abducted† by Cults features a woman being abducted by a man, and then the man driving down a very long and winding road while constantly looking out the window the entire time. The whole time, the woman is tied and trapped in the trunk of the car. Remembering parts of the past. At the end of the video, the guy parked the car near a cliff, gets out the car, lets the woman out of the trunk, and allows himself to be tied up by her and eventually locked in the trunk. Most of what has happened is in the past, and the video is showing her looking back at the past. The director leaves her still bound by her memories with only chalk to make marks. However, she is still alive. The end shows where the director currently saw her â€Å"lying alone,† in contemplation, trying to remember and make sense of the cruel experience. However, she is free and while unbinding herself will take her own effort, her future is now under her own control . Cults’s video â€Å"Abducted† shows us that love is winding like a road that can take you to places that you do not want to go. The lyrics to this song focus upon a relationship where the woman is completely infatuated with the man upon first sight. She realizes that this man is the best man she has ever been in a relationship with â€Å"I knew right then no one was above him†. she s saying that she knew this guy had her in his grips instantly. She knows that it is bad forShow MoreRelatedSir Gawain and the Green Knight Essay1636 Words   |  7 PagesCourtly Love and the Creation Myth in Sir Gawain and the Green Knight #9;Sir Gawain and the Green Knight, a great epic written in fourteenth century Europe by the Pearl poet, emphasizes the opposition of Christian love to Courtly love in the 13th century through the dilemma of Sir Gawain, one of the great knights of the Arthurian round table. By examining the women in the poem, Gawains dilemma becomes a metaphor for the contrast of these two distinct types of love. The poem looks upon the VirginRead More Sir Gawain and the Green Knight Essay1588 Words   |  7 PagesCourtly Love and the Creation Myth in Sir Gawain and the Green Knight nbsp;nbsp;nbsp;nbsp;nbsp;Sir Gawain and the Green Knight, a great epic written in fourteenth century Europe by the Pearl poet, emphasizes the opposition of Christian love to Courtly love in the 13th century through the dilemma of Sir Gawain, one of the great knights of the Arthurian round table. By examining the women in the poem, Gawains dilemma becomes a metaphor for the contrast of these two distinct types of love. The poemRead MoreShakespeare s Macbeth : Importance Of Secondary Characters1374 Words   |  6 Pagesbloody deed. The entire situation results with Macbeth seeking Banquo’s head to relive his mental angst. Additionally, the witches prove their ability to induce gory actions from preeminent characters in the play. For instance, the witches and their cult make their abilities apparent again when they make another prediction: Macbeth!... Beware Macduff Beware thane of Fife...no one woman born Shall harm Macbeth... Macbeth shall never vanquished be until Great Birnam Wood to high Dunsinane Hill ShallRead MoreCyrus The Great Is The Best Rulers Of All Of Human History1544 Words   |  7 Pagesreact better to rewards rather than punishment. Cyrus gains his knowledge of how to rule over human beings from several different sources from his early years. His first teacher was the justice school in Persia, second his experience with his grandfather in Media, and finally, and possibly his most important teacher, his father. First, as a boy, Cyrus learned about justice in Persia, where justice is the law. The boys in the school lean to â€Å"take vengeance on whomever they resolve to have done anyRead MoreWomen Writers Discussion Questions For Souls Belated3504 Words   |  15 PagesGannett journey through Europe by rail, Lydia is cautious to get married to Gannett. She is happily satisfied with herself and her oddness and nonconformity and forecasts that a marriage ceremony will wreck their care for each other. She comes into sight as a dissenter against the accepted, natural predictable conventional thoughts of the social order. She ends up become conscious that she desires society s endorsement more than she had initial ly thought. She does not accept as true that women haveRead MoreThe Whiteness of the Veil: Color and the veil in Hawthorne’s The Minister’s Black Veil and The Blithedale Romance1578 Words   |  6 Pagesappear darker than it actually is and dampens its natural colors. Despite wearing the black veil, Father Hooper can still be identified, albeit not easily. Upon the first confrontation with the minister wearing his veil, a parishioner voices his uncertainty about the identity of Father Hooper and requires confirmation by the sexton. During his first sermon, the audience half expects that stranger to be hiding beneath the black veil. Even more than doubt about identity, the veil causes doubt about theRead MoreJungian Theories Essay1301 Words   |  6 Pagesreligion and tradition. His childhood was filled with times spent alone exploring his fantasies and dreams which developed a life long interest in superstition and mythology. Later this would become the foundation fo r his theories, explains Pollock. At first, Jung entered the University of Basil interested in the field of archaeology, but his interests changed. In 1902, he graduated from the University of Zurich as an expert in the field of medicine (a doctor). Along with a good background on biology,Read MoreThe Field Of Nursing Care For The Ill Patients1927 Words   |  8 Pagesthese realms when one is to be fully healthy. 2. Healing Everybody wants healing from the sickness which one is affected with. There is a healing cult in religions where they try to give exclusive emphasize on the treatment or prevention by non-medical means of physical or spiritual ailments. They are mainly considered as attacks of evil. Such cults generally fall into one of three types: those centred on certain shrines or holy places, those centred on certain organizations and those centred onRead MoreRomeo And Juliet Comparing Stuff With Zeff And Luh1810 Words   |  8 Pagesadaptations. One a traditional Shakespearean film and the other a product of the MTV generation. Two very different films of the same love story. From the generations they come from they are very good examples of the things people were doing then but as an interpretation of text they both lack something which gives the story its element. Zeffirelli’s film best portrays love and passion. Both Baz Luhrmann and Franco Zeffirelli have been a popular choice for use in schools, due to their apparentRead More The Effects of Gender Bias on Elementary School Children Essay2293 Words   |  10 PagesThe Effects of Gender Bias on Elementary School Children â€Å"It’s a girl!† or â€Å"It’s a boy!† is typically the first thing parents hear after the birth of a child. This simple statement of fact sets the groundwork for every interaction they will have with their daughter or son, and for every experience that child will have throughout her or his life. Gender identity—the private experience of being female or male—forms a core part of one’s sense of self (Welker). The nature of this private experience