The Role of the Amygdala in Fear and Panic Essay -- Biology Essays Res

The Role of the Amygdala in Fear and Panic The definition of fear has proved to be an elusive mystery plaguing scientists. While there is much agreement as to the physiological effects of fear, the neural pathways and connections that bring upon these effects are not well understood. From the evolutionary standpoint, the theory is that fear is a neural circuit that has been designed to keep the organism alive in dangerous situations (1). How does it all work? Learning and responding to stimuli that warn of danger involves neural pathways that send information about the outside world to the amygdala, which in turn, determines the significance of the stimulus and triggers emotional responses like freezing or fleeing as well as changes in the inner workings of the body's organs and glands (1). There are important distinctions to make between emotions and feelings. Feelings are "red herrings", products of the conscious mind, labels given to unconscious emotions (2) whereas emotions are distinct patterns of behaviors of neurons. E motions can exist of conscious experiencesas well as physiological and neurological reactions and voluntary and involuntary behaviors (3). But the components of fear goes beyond feelings and emotions. It is also the specific memory of the emotion. After a frightful experience, one can remember the logical reasons for the experience (e.g. the time and place) but one will also "feel" the memory, and his body will react as such (i.e. increased heart and respiration rate, sweating). In one recent case, after a near drowining incident, the victim could not only vividly remember each detail, but when doing so, his body reacted as though he were reliving the experience. These feelings of memory are stored in an ... ... of being harmed at this particular moment. The three emotions can diffuse into one single diffuse state (5). Internet Sources: Isaacson, Robert. The Limbic System. Plenum Press, New York, NY, 1982 Thompson, Jack George. The Psychobiology of Emotions. Plenum Press, New York, NY, 1988 http://academic.uofs.edu/department/neuro/fear.html Van Goozen, Stephanie H. M. (ed.). Emotions: Essays on Emotion Theory. Lawrence Erlbaum Associates, Publishers, Hillsdale, N.J., 1994 Kavanaugh, Robert. Emotion: Interdisciplinary Perspectives. Lawrence Erlbaum Associates Publishers, Hillsdale, N.J., 1996 Muller, Jeff, "Functional Inactivation of the Lateral and Basal Nuclei of the Amygdala by Muscimol Infusion Prevents Fear Conditioning to an Explicit Conditioned Stimulus and to Contextual Stimuli". Behavioral Neuroscience, Vol. 111, No. 4, pp. 683-691, 1997

Cordination Compounds Essay

* FLEXIDENTATE CHARACTER OF POLYDENTATE LIGANDS; * Poly dentate ligands have flexi dentate character in the sense that all donors atoms may not form coordinate bonds with the central metal atom or ion. For example; EDTA which is the hexa dentate ligand also acts as tetra dentate or penta dentate in certain complexes. Similarly sulphate ion, which is a bi dentate ligand, also acts as a mono dentate ligand in certain complexes, e.g. in [Co(SO4)(NH3)5]Cl. * LABILE COMPLEXES; * A complex in which the ligands can be easily replaced by other ligands is called a labile complex. * GEOMETRY OF [CuX4]2- IONS; * The halide complex of Cu (2) shows two different stereo chemistries. In (NH4)2[CuCl4], [CuCl4]2- ion is square planar, but Cs2[CuCl4] and Cs2[CuBr4], the [CuX4]2- ions have a slightly squashed tetrahedral shape. Tetrahedral [CuCl4]2- ions are orange whereas, square planar [CuCl4]2- ions are yellow in colour. * GREATER STABILITY OF Co(+3) COMPLEXES THAN Co(+2) COMPLEXES; * Co+2 ions are very stable & are difficult to oxidise. Co+3 ions are less stable and are readily reduced by water to Co2+. In contrast Co(+2) are less stable and are readily oxidised to Co(+3) complexes, i.e. Co(3) are very stable. This is because CFSE of Co(+3) with d6 configuration is higher than Co(+2) with d7 configuration. * SIDGWICK THEORY OR EFFECTIVE ATOMIC NUMBER (EAN) RULE; * Sidgwick put forward a rule to explain the stability of complexes on the basis of effective atomic number as follows:- EAN of metal in complex= atomic number –oxidation state+2Ãâ€" co-ordination number A stable complex is formed if the EAN is equal to the atomic number of the next noble gas. Thus, from the calculation given in the table below, [Fe(CN)6]4- is more stable than [Fe(CN)6]3- Though this rule is found to be applicable in many cases, yet it fails in no. Of cases as illustrated by last two examples given in the table below: complex| Oxidation state| Atomic number | Co-ordination number| EAN| [Co(NH3)6]3+| +3| 27| 6| 27-3+2Ãâ€"6=36, i.e. [Kr]| [Fe(CN)6]4-| +2| 26| 6| 26-2+2Ãâ€"6=36, i.e. [Kr]| [PtCl6]2-| +4| 78| 6| 78-4+2Ãâ€"6=86, i.e. [Rn]| [Fe(CN)6]3-| +3| 26| 6| 26-3+2Ãâ€"6=35| [Ag(NH3)2]1+| +1| 47| 2| 47-1+2Ãâ€"2=50|

The Past And The Future - 1802 Words

The Present The past and the future are constantly battling over ownership of the present. The influences of tradition and culture keep current times rooted in history, while technological breakthroughs and the hope of improvement keep humanity looking to the future. This same struggle stretches to the realm of societal morality, where the past insists upon the existence of God, while the future demands that civilization exist without the influence of divinity. In Friedrich Nietzsche’s book, The Gay Science, one of the characters argues that the purity of traditional morality has given way to the imperfect and immoral ideals of human nature and societal progression. Friedrich Nietzsche lived from 1844 to 1900 in the country that was†¦show more content†¦When the American colonies separated from the British Empire in 1776, United States citizens were filled with an ardor for nationalism, freedom and self ­sufficiency that has remained in the hearts of Americans to this day. One of the fundamental policies adopted due to this appreciation for self ­rule and liberty is the economic system known as capitalism. And although the United States government set out on a mission to spread propaganda in the 1940s in order to highlight the superiority of capitalism over socialism, our beloved laissez ­faire system has a major dark ­side (Picture). â€Å"According to the United States Department of Labor, over 50% of U.S. garment factories are sweatshops.10 ­12 hour days, six to seven days a week are the regular hours that garment workers toil in the United States† (Homeworkers Under the Fair Labor Standards Act 1). Capitalism runs o n self ­interest, and encourages the exploitation of the people who are the most vulnerable – women, children and migrant workers (Mayday). Under the capitalistic form of economy, powerful individuals are encouraged to take advantage of their workers in order to gain profit for themselves. This system puts the disenfranchised at the mercy of the controlling