Reward-sensitivity

The hypothesis that a robust rewarding effect depends on continuing novelty is consistent with recent reports that reward-sensitive dopaminergic cells in a monkey s nucleus accumbens respond most when a rewarding stimulus occurs unpredictably (Hollerman, Tremblay, and Schultz 1998). 

Independently of the impact of addiction on rationality and reward sensitivity, we may ask whether the state may be the result of a choice— even a rational choice—to become addicted. Among the three choice-theoretic approaches to this issue, one assumes rational choice under certainty (Becker and Murphy 1988), another rational choice under risk (Orphanides and Zervos 1995), and a third that we may call "choice under... 

Shumake, J., Barrett, D., and Gonazalez-Lima, F. (2005). Behavioral characteristics of rats predisposed to learned helplessness Reduced reward sensitivity, increased novelty seeking, and persistent fear memories. Bekav. Brain Res. 164, 222-230. 

Kenny PJ, Markou A. Nicotine self-administration acutely activates brain reward systems and induces a long-lasting increase in reward sensitivity. Neuropsychopharmacology 2006 31 1203-1211. 

In 1954, experiments by Olds and Milner revealed that the brain has specialized centers for reward functions. In these studies electrical stimulation of certain brain sites was found to be highly rewarding in the sense that rats operantly respond for electrical stimulation of these brain sites, often to the exclusion of any other activity. A neurotransmitter system that is particularly sensitive to electrical self-stimulation is the mesolimbic dopamine projection that originates in the ventral tegmental area and projects to structures closely... 

Kleber HD, Weissman MM, Rounsaville BJ, et al Imipramine as treatment for depression in addicts. Arch Gen Psychiatry 40 649-633, 1983 Kleber HD, Riordan CE, Rounsaville BJ, et al Clonidine in outpatient detoxification from methadone maintenance. Arch Gen Psychiatry 42 391-394, 1983 Kleber HD, Topazian M, Gaspari J, et al Clonidine and naltrexone in the outpatient treatment of heroin withdrawal. Am J Drug Alcohol Abuse 13 1-17, 1987 Kornetsky C. Brain stimulation reward, morphine-induced stereotypy, and sensitization implications for abuse. Neurosci Biobehav Rev 27 777-786, 2004 Kosten TR, Kleber HD Buprenorphine detoxification from opioid dependence a pilot study. Life Sci 42 633-641, 1988... 

A study that examined the interaction between exposure concentration and time of exposure on nervous system function found that concentration, rather than time of exposure, was more important in determining effects (Bushnell 1997). Rats were trained to press two levers for food reward one lever when a light flashed, the second lever produced food when there was no signal. The trained rats were exposed to 0,400, 800, 1,200, 1,600,2,000, or 2,400 ppm trichloroethylene for 0.33, 0.67, or 1 hour. Response times were signiflcantly increased only at 2,400 ppm at 0.67 and 1 hour. Sensitivity was significantly decreased at 2,400 ppm at all exposure times. At 0.33 hour, sensitivity was not affected at the other concentrations. At 0.67 hour, sensitivity was significantly decreased at 2,000, and 1,200 ppm, and at 1 hour, sensitivity was... 

In summary, the polysilanes comprise a new class of scientifically interesting, radiation sensitive materials for which many applications have become recently apparent. There is every reason to believe that future investigations will continue to be scientifically rewarding and result in new applications. 

Tapper, A.R., McKinney, S.L., Nashmi, R. et al. Nicotine activation of alpha4 receptors sufficient for reward, tolerance, and sensitization. Science. 306 1029, 2004. 

Laviolette, S.R., van der Kooy, D. Blockade of mesolimbic dopamine transmission dramatically increases sensitivity to the rewarding effects of nicotine in the ventral tegmental area. Mol. Psychiatry. 8 50, 2003. 

Hiroi, N., Brown, J.R., Haile, C.N. et al. FosB mutant mice loss of chronic cocaine induction of Fos-related proteins and heightened sensitivity to cocaine s psychomotor and rewarding effects. Proc. Natl. Acad. Sci. U.S.A. 94 10397, 1997. 

Shippenberg T., Heidbreder C. Sensitization to the conditioned rewarding effects of cocaine pharmacological and temporal characteristics. J. Pharmacol. Exp. Ther. 273 808, 1995. 

Shippenberg T., Heidbreder C. Kappa opioid receptor agonists prevent sensitization to the rewarding effects of cocaine. NIDA Res. Monogr. 153 456, 1994. 

Luetje CW, Patrick J (1991) Both alpha- and beta-subunits contribute to the agonist sensitivity of neuronal nicotinic acetylchohne receptors. J Neurosci 11 837-845 MameU-EngvaU M, Evrard A, Pons S, Maskos U, Svensson TH, Changeux JP, Faure P (2006) Hierarchical control of dopamine neuron-firing patterns by nicotinic receptors. Neuron 50 911-921 Mansvelder HD, McGehee DS (2000) Long-term potentiation of excitatory inputs to brain reward areas by nicotine. Neuron 27 349-357... 

In my case, I had more than just the "t" to fix. I had to de-pro-gram my stubbornness, over-sensitivity to criticism, self-consciousness, and boost my self-esteem. Dr. Walker was probably pra dng that my "sarcasm" would find it s way to the exit, as well. Luckily, at the age of just fourteen, I listened. I thought about the simple risk vs. reward system for making a decision. 

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